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Kuhl Y, Mueller F, Naunheim S, Bovelett M, Lambertus J, Schug D, Weissler B, Gegenmantel E, Gebhardt P, Schulz V. A finely segmented semi-monolithic detector tailored for high-resolution PET. Med Phys 2024; 51:3421-3436. [PMID: 38214395 DOI: 10.1002/mp.16928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/20/2023] [Accepted: 12/20/2023] [Indexed: 01/13/2024] Open
Abstract
BACKGROUND Preclinical research and organ-dedicated applications use and require high (spatial-)resolution positron emission tomography (PET) detectors to visualize small structures (early) and understand biological processes at a finer level of detail. Researchers seeking to improve detector and image spatial resolution have explored various detector designs. Current commercial high-resolution systems often employ finely pixelated or monolithic scintillators, each with its limitations. PURPOSE We present a semi-monolithic detector, tailored for high-resolution PET applications with a spatial resolution in the range of 1 mm or better, merging concepts of monolithic and pixelated crystals. The detector features LYSO slabs measuring (24 × 10 × 1) mm3, coupled to a 12 × 12 readout channel photosensor with 4 mm pitch. The slabs are grouped in two arrays of 44 slabs each to achieve a higher optical photon density despite the fine segmentation. METHODS We employ a fan beam collimator for fast calibration to train machine-learning-based positioning models for all three dimensions, including slab identification and depth-of-interaction (DOI), utilizing gradient tree boosting (GTB). The data for all dimensions was acquired in less than 2 h. Energy calculation was based on a position-dependent energy calibration. Using an analytical timing calibration, time skews were corrected for coincidence timing resolution (CTR) estimation. RESULTS Leveraging machine-learning-based calibration in all three dimensions, we achieved high detector spatial resolution: down to 1.18 mm full width at half maximum (FWHM) detector spatial resolution and 0.75 mm mean absolute error (MAE) in the planar-monolithic direction, and 2.14 mm FWHM and 1.03 mm MAE for DOI at an energy window of (435-585) keV. Correct slab interaction identification in planar-segmented direction exceeded 80%, alongside an energy resolution of 12.7% and a CTR of 450 ps FWHM. CONCLUSIONS The introduced finely segmented, high-resolution slab detector demonstrates appealing performance characteristics suitable for high-resolution PET applications. The current benchtop-based detector calibration routine allows these detectors to be used in PET systems.
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Affiliation(s)
- Yannick Kuhl
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Florian Mueller
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Stephan Naunheim
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Matthias Bovelett
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Janko Lambertus
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Bjoern Weissler
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | | | - Pierre Gebhardt
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
- Physics Institute III B, RWTH Aachen University, Aachen, Germany
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Baskaya F, Lemainque T, Klinkhammer B, Koletnik S, von Stillfried S, Talbot SR, Boor P, Schulz V, Lederle W, Kiessling F. Pathophysiologic Mapping of Chronic Liver Diseases With Longitudinal Multiparametric MRI in Animal Models. Invest Radiol 2024:00004424-990000000-00209. [PMID: 38598653 DOI: 10.1097/rli.0000000000001075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
OBJECTIVES Chronic liver diseases (CLDs) have diverse etiologies. To better classify CLDs, we explored the ability of longitudinal multiparametric MRI (magnetic resonance imaging) in depicting alterations in liver morphology, inflammation, and hepatocyte and macrophage activity in murine high-fat diet (HFD)- and carbon tetrachloride (CCl4)-induced CLD models. MATERIALS AND METHODS Mice were either untreated, fed an HFD for 24 weeks, or injected with CCl4 for 8 weeks. Longitudinal multiparametric MRI was performed every 4 weeks using a 7 T MRI scanner, including T1/T2 relaxometry, morphological T1/T2-weighted imaging, and fat-selective imaging. Diffusion-weighted imaging was applied to assess fibrotic remodeling and T1-weighted and T2*-weighted dynamic contrast-enhanced MRI and dynamic susceptibility contrast MRI using gadoxetic acid and ferucarbotran to target hepatocytes and the mononuclear phagocyte system, respectively. Imaging data were associated with histopathological and serological analyses. Principal component analysis and clustering were used to reveal underlying disease patterns. RESULTS The MRI parameters significantly correlated with histologically confirmed steatosis, fibrosis, and liver damage, with varying importance. No single MRI parameter exclusively correlated with 1 pathophysiological feature, underscoring the necessity for using parameter patterns. Clustering revealed early-stage, model-specific patterns. Although the HFD model exhibited pronounced liver fat content and fibrosis, the CCl4 model indicated reduced liver fat content and impaired hepatocyte and macrophage function. In both models, MRI biomarkers of inflammation were elevated. CONCLUSIONS Multiparametric MRI patterns can be assigned to pathophysiological processes and used for murine CLD classification and progression tracking. These MRI biomarker patterns can directly be explored clinically to improve early CLD detection and differentiation and to refine treatments.
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Affiliation(s)
- Ferhan Baskaya
- From the Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (F.B., T.L., S.K., V.S., W.L., F.K.); Department for Diagnostic and Interventional Radiology, RWTH Aachen University, Aachen, Germany (T.L.); Institute of Pathology, RWTH Aachen University, Aachen, Germany (B.K., S.S., P.B.); and Institute for Laboratory Animal Science, Hannover Medical School, Hannover, Germany (S.R.T.)
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May JN, Moss JI, Mueller F, Golombek SK, Biancacci I, Rizzo L, Elshafei AS, Gremse F, Pola R, Pechar M, Etrych T, Becker S, Trautwein C, Bülow RD, Boor P, Knuechel R, von Stillfried S, Storm G, Puri S, Barry ST, Schulz V, Kiessling F, Ashford MB, Lammers T. Histopathological biomarkers for predicting the tumour accumulation of nanomedicines. Nat Biomed Eng 2024:10.1038/s41551-024-01197-4. [PMID: 38589466 DOI: 10.1038/s41551-024-01197-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 02/08/2024] [Indexed: 04/10/2024]
Abstract
The clinical prospects of cancer nanomedicines depend on effective patient stratification. Here we report the identification of predictive biomarkers of the accumulation of nanomedicines in tumour tissue. By using supervised machine learning on data of the accumulation of nanomedicines in tumour models in mice, we identified the densities of blood vessels and of tumour-associated macrophages as key predictive features. On the basis of these two features, we derived a biomarker score correlating with the concentration of liposomal doxorubicin in tumours and validated it in three syngeneic tumour models in immunocompetent mice and in four cell-line-derived and six patient-derived tumour xenografts in mice. The score effectively discriminated tumours according to the accumulation of nanomedicines (high versus low), with an area under the receiver operating characteristic curve of 0.91. Histopathological assessment of 30 tumour specimens from patients and of 28 corresponding primary tumour biopsies confirmed the score's effectiveness in predicting the tumour accumulation of liposomal doxorubicin. Biomarkers of the tumour accumulation of nanomedicines may aid the stratification of patients in clinical trials of cancer nanomedicines.
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Affiliation(s)
- Jan-Niklas May
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
| | - Jennifer I Moss
- Early TDE Discovery, Oncology R&D, AstraZeneca, Cambridge, UK
| | - Florian Mueller
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
| | - Susanne K Golombek
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
| | - Ilaria Biancacci
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
| | - Larissa Rizzo
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
| | - Asmaa Said Elshafei
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
| | - Felix Gremse
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
- Gremse-IT GmbH, Aachen, Germany
| | - Robert Pola
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Michal Pechar
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Tomáš Etrych
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Svea Becker
- Clinic for Gastroenterology, Metabolic Disorders, and Internal Intensive Medicine, University Hospital RWTH Aachen, Aachen, Germany
| | - Christian Trautwein
- Clinic for Gastroenterology, Metabolic Disorders, and Internal Intensive Medicine, University Hospital RWTH Aachen, Aachen, Germany
- Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf, Aachen, Germany
| | - Roman D Bülow
- Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf, Aachen, Germany
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Peter Boor
- Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf, Aachen, Germany
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Ruth Knuechel
- Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf, Aachen, Germany
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Saskia von Stillfried
- Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf, Aachen, Germany
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Gert Storm
- Department of Pharmaceutics, Utrecht University, Utrecht, the Netherlands
- Department of Biomaterials, Science and Technology, University of Twente, Enschede, the Netherlands
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Sanyogitta Puri
- Advanced Drug Delivery, Pharmaceutical Sciences, R&D, AstraZeneca, Macclesfield, UK
| | - Simon T Barry
- Early TDE Discovery, Oncology R&D, AstraZeneca, Cambridge, UK
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany
- Physics Institute III B, RWTH Aachen University, Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany
- Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf, Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany
| | - Marianne B Ashford
- Advanced Drug Delivery, Pharmaceutical Sciences, R&D, AstraZeneca, Macclesfield, UK
| | - Twan Lammers
- Institute for Experimental Molecular Imaging, University Hospital RWTH Aachen, Aachen, Germany.
- Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf, Aachen, Germany.
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Hetzel R, Urbanevych V, Bolke A, Kasper J, Kercz M, Kołodziej M, Magiera A, Mueller F, Müller S, Rafecas M, Rusiecka K, Schug D, Schulz V, Stahl A, Weissler B, Wong ML, Wrońska A. Near-field coded-mask technique and its potential for proton therapy monitoring. Phys Med Biol 2023; 68:245028. [PMID: 37863101 DOI: 10.1088/1361-6560/ad05b2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 10/20/2023] [Indexed: 10/22/2023]
Abstract
Objective.Prompt-gamma imaging encompasses several approaches to the online monitoring of the beam range or deposited dose distribution in proton therapy. We test one of the imaging techniques - a coded mask approach - both experimentally and via simulations.Approach.Two imaging setups have been investigated experimentally. Each of them comprised a structured tungsten collimator in the form of a modified uniformly redundant array mask and a LYSO:Ce scintillation detector of fine granularity. The setups differed in detector dimensions and operation mode (1D or 2D imaging). A series of measurements with radioactive sources have been conducted, testing the performance of the setups for near-field gamma imaging. Additionally, Monte Carlo simulations of a larger setup of the same type were conducted, investigating its performance with a realistic gamma source distribution occurring during proton therapy.Main results.The images of point-like sources reconstructed from two small-scale prototypes' data using the maximum-likelihood expectation maximisation algorithm constitute the experimental proof of principle for the near-field coded-mask imaging modality, both in the 1D and the 2D mode. Their precision allowed us to calibrate out certain systematic offsets appearing due to the limited alignment accuracy of setup elements. The simulation of the full-scale setup yielded a mean distal falloff retrieval precision of 0.72 mm in the studies for beam energy range 89.5-107.9 MeV and with 1 × 108protons (a typical number for distal spots). The implemented algorithm of image reconstruction is relatively fast-a typical procedure needs several seconds.Significance.Coded-mask imaging appears a valid option for proton therapy monitoring. The results of simulations let us conclude that the proposed full-scale setup is competitive with the knife-edge-shaped and the multi-parallel slit cameras investigated by other groups.
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Affiliation(s)
- Ronja Hetzel
- III. Physikalisches Institut B, RWTH Aachen University, Aachen, Germany
| | - Vitalii Urbanevych
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
| | - Andreas Bolke
- Institute of Medical Engineering, University of Lübeck, Lübeck, Germany
| | - Jonas Kasper
- III. Physikalisches Institut B, RWTH Aachen University, Aachen, Germany
| | - Monika Kercz
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
- Doctoral School of Exact and Natural Sciences, Jagiellonian University, Kraków, Poland
| | - Magdalena Kołodziej
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
- Doctoral School of Exact and Natural Sciences, Jagiellonian University, Kraków, Poland
| | - Andrzej Magiera
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
| | - Florian Mueller
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Sara Müller
- III. Physikalisches Institut B, RWTH Aachen University, Aachen, Germany
| | - Magdalena Rafecas
- Institute of Medical Engineering, University of Lübeck, Lübeck, Germany
| | - Katarzyna Rusiecka
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
| | - David Schug
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Volkmar Schulz
- III. Physikalisches Institut B, RWTH Aachen University, Aachen, Germany
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Achim Stahl
- III. Physikalisches Institut B, RWTH Aachen University, Aachen, Germany
| | - Bjoern Weissler
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Ming-Liang Wong
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
| | - Aleksandra Wrońska
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
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Nadig V, Hornisch M, Oehm J, Herweg K, Schulz V, Gundacker S. 16-channel SiPM high-frequency readout with time-over-threshold discrimination for ultrafast time-of-flight applications. EJNMMI Phys 2023; 10:76. [PMID: 38044383 PMCID: PMC10694125 DOI: 10.1186/s40658-023-00594-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/20/2023] [Indexed: 12/05/2023] Open
Abstract
BACKGROUND Over the past five years, ultrafast high-frequency (HF) readout concepts have advanced the timing performance of silicon photomultipliers (SiPMs). The shown impact in time-of-flight (TOF) techniques can further push the limits in light detection and ranging (LiDAR), time-of-flight positron-emission tomography (TOF-PET), time-of-flight computed tomography (TOF-CT) or high-energy physics (HEP). However, upscaling these electronics to a system-applicable, multi-channel readout, has remained a challenging task, posed by the use of discrete components and a high power consumption. To this day, there are no means to exploit the high TOF resolution of these electronics on system scale or to measure the actual timing performance limits of a full detector block. METHODS In this work, we present a 16-channel HF readout board, including leading-edge discrimination and a linearized time-over-threshold (TOT) method, which is fully compatible with a high-precision time-to-digital converters (TDCs), such as the picoTDC developed at CERN. The discrete implementation allows ideal adaptation of this readout to a broad range of detection tasks. As a first step, the functionality of the circuit has been tested using the TOFPET2 ASIC as back-end electronics to emulate the TDC, also in view of its properties as a highly scalable data acquisition solution. RESULTS The produced board is able to mitigate influences of baseline shifts in the TOFPET2 front end, which has been shown in experiments with a pulsed laser, increasing the achievable intrinsic coincidence timing resolution (CTR) of the TOFPET2 readout electronics from 70 ps (FWHM) to 62 ps (FWHM). Single-channel coincidence experiments including a [Formula: see text]-source, 2[Formula: see text]2[Formula: see text]3 mm[Formula: see text] LYSO:Ce,Ca crystals and Broadcom NUV-MT SiPMs resulted in a CTR of 118 ps (FWHM). For a 4[Formula: see text]4 matrix of 3.88[Formula: see text]3.88[Formula: see text]19 mm[Formula: see text] LYSO:Ce,Ca crystals one-to-one coupled to a 4[Formula: see text]4 array of Broadcom NUV-MT SiPMs, an average CTR of 223 ps (FWHM) was obtained. CONCLUSION The implemented 16-channel HF electronics are fully functionall and have a negligible influence on the timing performance of the back-end electronics used, here the TOFPET2 ASIC. The ongoing integration of the picoTDC with the 16-channel HF board is expected to further set the path toward sub-100 ps TOF-PET and sub-30ps TOF resolution for single-photon detection.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Matthias Hornisch
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Jakob Oehm
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Katrin Herweg
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Pauwelsstraße 19, 52074, Aachen, Germany
- III. Physikalisches Institut B, RWTH Aachen University, Otto-Blumenthal-Straße, 52074, Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Stefan Gundacker
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany.
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Naunheim S, Kuhl Y, Schug D, Schulz V, Mueller F. Improving the Timing Resolution of Positron Emission Tomography Detectors Using Boosted Learning-A Residual Physics Approach. IEEE Trans Neural Netw Learn Syst 2023; PP:1-13. [PMID: 37862278 DOI: 10.1109/tnnls.2023.3323131] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2023]
Abstract
Artificial intelligence (AI) is entering medical imaging, mainly enhancing image reconstruction. Nevertheless, improvements throughout the entire processing, from signal detection to computation, potentially offer significant benefits. This work presents a novel and versatile approach to detector optimization using machine learning (ML) and residual physics. We apply the concept to positron emission tomography (PET), intending to improve the coincidence time resolution (CTR). PET visualizes metabolic processes in the body by detecting photons with scintillation detectors. Improved CTR performance offers the advantage of reducing radioactive dose exposure for patients. Modern PET detectors with sophisticated concepts and read-out topologies represent complex physical and electronic systems requiring dedicated calibration techniques. Traditional methods primarily depend on analytical formulations successfully describing the main detector characteristics. However, when accounting for higher-order effects, additional complexities arise matching theoretical models to experimental reality. Our work addresses this challenge by combining traditional calibration with AI and residual physics, presenting a highly promising approach. We present a residual physics-based strategy using gradient tree boosting and physics-guided data generation. The explainable AI framework SHapley Additive exPlanations (SHAPs) was used to identify known physical effects with learned patterns. In addition, the models were tested against basic physical laws. We were able to improve the CTR significantly (more than 20%) for clinically relevant detectors of 19 mm height, reaching CTRs of 185 ps (450-550 keV).
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Kiessling F, Schulz V. Perspectives of Evidence-Based Therapy Management. Nuklearmedizin 2023; 62:314-322. [PMID: 37802059 DOI: 10.1055/a-2159-6949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/08/2023]
Abstract
BACKGROUND Therapeutics that specifically address biological processes often require a much finer selection of patients and subclassification of diseases. Thus, diagnostic procedures must describe the diseases in sufficient detail to allow selection of appropriate therapy and to sensitively track therapy response. Anatomical features are often not sufficient for this purpose and there is a need to image molecular and pathophysiological processes. METHOD Two imaging strategies can be pursued: molecular imaging attempts to image a few biomarkers that play key roles in pathological processes. Alternatively, patterns describing a biological process can be identified from the synopsis of multiple (non-specific) imaging markers, possibly in combination with omics and other clinical findings. Here, AI-based methods are increasingly being used. RESULTS Both strategies of evidence-based therapy management are explained in this review article and examples and clinical successes are presented. In this context, reviews of clinically approved molecular diagnostics and decision support systems are listed. Furthermore, since reliable, representative, and sufficiently large datasets are further important prerequisites for AI-assisted multiparametric analyses, concepts are presented to make data available in a structured way, e. g., using Generative Adversarial Networks to complement databases with virtual cases and to build completely anonymous reference databases. CONCLUSION Molecular imaging and computer-assisted cluster analysis of diagnostic data are complementary methods to describe pathophysiological processes. Both methods have the potential to improve (evidence-based) the future management of therapies, partly on their own but also in combined approaches. KEY POINTS · Molecular imaging and radiomics provide valuable complementary disease biomarkers.. · Data-driven, model-based, and hybrid model-based integrated diagnostics advance precision medicine.. · Synthetic data generation may become essential in the development process of future AI methods..
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Affiliation(s)
- Fabian Kiessling
- Universitätsklinikum Aachen, Lehrstuhl für Experimentelle Molekulare Bildgebung, Aachen, Germany
- Group Aachen, Fraunhofer-Institut für Digitale Medizin MEVIS, Bremen, Germany
| | - Volkmar Schulz
- Universitätsklinikum Aachen, Lehrstuhl für Experimentelle Molekulare Bildgebung, Aachen, Germany
- Group Aachen, Fraunhofer-Institut für Digitale Medizin MEVIS, Bremen, Germany
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Gundacker S, Borghi G, Cherry SR, Gola A, Lee D, Merzi S, Penna M, Schulz V, Kwon SI. On timing-optimized SiPMs for Cherenkov detection to boost low cost time-of-flight PET. Phys Med Biol 2023; 68:165016. [PMID: 37467766 PMCID: PMC10410404 DOI: 10.1088/1361-6560/ace8ee] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/10/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023]
Abstract
Objective.Recent SiPM developments and improved front-end electronics have opened new doors in TOF-PET with a focus on prompt photon detection. For instance, the relatively high Cherenkov yield of bismuth-germanate (BGO) upon 511 keV gamma interaction has triggered a lot of interest, especially for its use in total body positron emission tomography (PET) scanners due to the crystal's relatively low material and production costs. However, the electronic readout and timing optimization of the SiPMs still poses many questions. Lab experiments have shown the prospect of Cherenkov detection, with coincidence time resolutions (CTRs) of 200 ps FWHM achieved with small pixels, but lack system integration due to an unacceptable high power uptake of the used amplifiers.Approach.Following recent studies the most practical circuits with lower power uptake (<30 mW) have been implemented and the CTR performance with BGO of newly developed SiPMs from Fondazione Bruno Kessler tested. These novel SiPMs are optimized for highest single photon time resolution (SPTR).Main results.We achieved a best CTR FWHM of 123 ps for 2 × 2 × 3 mm3and 243 ps for 3 × 3 × 20 mm3BGO crystals. We further show that with these devices a CTR of 106 ps is possible using commercially available 3 × 3 × 20 mm3LYSO:Ce,Mg crystals. To give an insight in the timing properties of these SiPMs, we measured the SPTR with black coated PbF2of 2 × 2 × 3 mm3size. We confirmed an SPTR of 68 ps FWHM published in literature for standard devices and show that the optimized SiPMs can improve this value to 42 ps. Pushing the SiPM bias and using 1 × 1 mm2area devices we measured an SPTR of 28 ps FWHM.Significance.We have shown that advancements in readout electronics and SiPMs can lead to improved CTR with Cherenkov emitting crystals. Enabling time-of-flight with BGO will trigger a high interest for its use in low-cost and total-body PET scanners. Furthermore, owing to the prompt nature of Cherenkov emission, future CTR improvements are conceivable, for which a low-power electronic implementation is indispensable. In an extended discussion we will give a roadmap to best timing with prompt photons.
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Affiliation(s)
- Stefan Gundacker
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstrae 55, D-52074 Aachen, Germany
| | - Giacomo Borghi
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States of America
| | - Alberto Gola
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
| | - Daehee Lee
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States of America
| | - Stefano Merzi
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
| | - Michele Penna
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
- Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstrae 55, D-52074 Aachen, Germany
| | - Sun Il Kwon
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States of America
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Weindel K, Nadig V, Herweg K, Schulz V, Gundacker S. A time-based double-sided readout concept of 100 mm LYSO:Ce,Ca fibres for future axial TOF-PET. EJNMMI Phys 2023; 10:43. [PMID: 37450099 PMCID: PMC10349027 DOI: 10.1186/s40658-023-00563-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/05/2023] [Indexed: 07/18/2023] Open
Abstract
BACKGROUND Positron emission tomography (PET) requires a high signal-to-noise ratio (SNR) to improve image quality, with time-of-flight (TOF) being an effective way to boost the SNR. However, the scanner sensitivity and resolution must be maintained. The use of axially aligned 100-mm LYSO:Ce,Ca scintillation crystals with double-sided readout has the potential of ground-breaking TOF and sensitivity, while reducing parallax errors through depth-of-interaction (DOI) estimation, and also allowing a reduction in the number of readout channels required, resulting in cost benefits. Due to orientation, these fibres may also facilitate the integration of TOF-PET with magnetic resonance imaging (MRI) in hybrid imaging systems. The challenge of achieving a good spatial resolution with such long axial fibres is directly related to the achievable TOF resolution. In this study, the timing performance and DOI resolution of emerging high-performance materials were investigated to assess the merits of this approach in organ-dedicated or total-body/large-scale PET imaging systems. METHODS LYSO:Ce,Ca scintillation fibres of 20 mm and 100 mm length were tested in various operating and readout configurations to determine the best achievable coincidence time resolution (CTR) and DOI resolution. The tests were performed using state-of-the-art high-frequency (HF) readout and commercially available silicon photomultipliers (SiPMs) from Broadcom Inc. RESULTS For the 100-mm fibre, an average CTR performance of [Formula: see text] ps FWHM and an average depth-of-interaction resolution within the fibre of [Formula: see text] mm FWHM could be obtained. The 20-mm fibre showed a sub-100 ps CTR of [Formula: see text] ps FWHM and a fibre resolution of [Formula: see text] mm FWHM in the double-sided readout configuration. CONCLUSION With modern SiPMs and crystals, a double-sided readout of long fibres can achieve excellent timing resolution and field-advancing TOF resolution, outperforming commercial PET systems. With 100-mm fibres, an electronic channel reduction of about a factor 2.5 is inherent, with larger reduction factors conceivable, which can lead to lower production costs. The spatial resolution was shown to be limited in the axial direction with 12 mm, but is defined to 3 mm in all other directions. Recent SiPM and scintillator developments are expected to improve on the time and spatial resolution to be investigated in future prototypes.
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Affiliation(s)
- Konstantin Weindel
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Katrin Herweg
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
- Physics Institute III B, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Stefan Gundacker
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
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Müller-Franzes G, Huck L, Tayebi Arasteh S, Khader F, Han T, Schulz V, Dethlefsen E, Kather JN, Nebelung S, Nolte T, Kuhl C, Truhn D. Using Machine Learning to Reduce the Need for Contrast Agents in Breast MRI through Synthetic Images. Radiology 2023; 307:e222211. [PMID: 36943080 DOI: 10.1148/radiol.222211] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Background Reducing the amount of contrast agent needed for contrast-enhanced breast MRI is desirable. Purpose To investigate if generative adversarial networks (GANs) can recover contrast-enhanced breast MRI scans from unenhanced images and virtual low-contrast-enhanced images. Materials and Methods In this retrospective study of breast MRI performed from January 2010 to December 2019, simulated low-contrast images were produced by adding virtual noise to the existing contrast-enhanced images. GANs were then trained to recover the contrast-enhanced images from the simulated low-contrast images (approach A) or from the unenhanced T1- and T2-weighted images (approach B). Two experienced radiologists were tasked with distinguishing between real and synthesized contrast-enhanced images using both approaches. Image appearance and conspicuity of enhancing lesions on the real versus synthesized contrast-enhanced images were independently compared and rated on a five-point Likert scale. P values were calculated by using bootstrapping. Results A total of 9751 breast MRI examinations from 5086 patients (mean age, 56 years ± 10 [SD]) were included. Readers who were blinded to the nature of the images could not distinguish real from synthetic contrast-enhanced images (average accuracy of differentiation: approach A, 52 of 100; approach B, 61 of 100). The test set included images with and without enhancing lesions (29 enhancing masses and 21 nonmass enhancement; 50 total). When readers who were not blinded compared the appearance of the real versus synthetic contrast-enhanced images side by side, approach A image ratings were significantly higher than those of approach B (mean rating, 4.6 ± 0.1 vs 3.0 ± 0.2; P < .001), with the noninferiority margin met by synthetic images from approach A (P < .001) but not B (P > .99). Conclusion Generative adversarial networks may be useful to enable breast MRI with reduced contrast agent dose. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Bahl in this issue.
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Affiliation(s)
- Gustav Müller-Franzes
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Luisa Huck
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Soroosh Tayebi Arasteh
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Firas Khader
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Tianyu Han
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Volkmar Schulz
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Ebba Dethlefsen
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Jakob Nikolas Kather
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Sven Nebelung
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Teresa Nolte
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Christiane Kuhl
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
| | - Daniel Truhn
- From the Department of Diagnostic and Interventional Radiology (G.M.F., L.H., S.T.A., F.K., E.D., S.N., T.N., C.K., D.T.) and Department of Medicine III (J.N.K.), University Hospital RWTH Aachen, Pauwelsstrasse 30, Aachen 52074, Germany; and Department of Physics of Molecular Imaging Systems, Division of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (T.H., V.S.)
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Nadig V, Herweg K, Chou MMC, Lin JWC, Chin E, Li CA, Schulz V, Gundacker S. Timing advances of commercial divalent-ion co-doped LYSO:Ce and SiPMs in sub-100 ps time-of-flight positron emission tomography. Phys Med Biol 2023; 68. [PMID: 36808914 DOI: 10.1088/1361-6560/acbde4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/21/2023] [Indexed: 02/23/2023]
Abstract
Objective.Together with novel photodetector technologies and emerging electronic front-end designs, scintillator material research is one of the key aspects to obtain ultra-fast timing in time-of-flight positron emission tomography (TOF-PET). In the late 1990s, Cerium-doped lutetium-yttrium oxyorthosilicate (LYSO:Ce) has been established as the state-of-the-art PET scintillator due to its fast decay time, high light yield and high stopping power. It has been shown that co-doping with divalent ions, such as Ca2+and Mg2+, is beneficial for its scintillation characteristics and timing performance. Therefore, this work aims to identify a fast scintillation material to combine it with novel photosensor technologies to push the state of the art in TOF-PET.Approach.This study evaluates commercially available LYSO:Ce,Ca and LYSO:Ce,Mg samples manufactured by Taiwan Applied Crystal Co., LTD regarding their rise and decay times as well as their coincidence time resolution (CTR) with both ultra-fast high-frequency (HF) readout and commercially available readout electronics, i.e. the TOFPET2 ASIC.Main results.The co-doped samples exhibit state-of-the-art rise times of on average 60 ps and effective decay times of on average 35 ns. Using the latest technological improvements made on NUV-MT SiPMs by Fondazione Bruno Kessler and Broadcom Inc., a 3 × 3 × 19 mm3LYSO:Ce,Ca crystal achieves a CTR of 95 ps (FWHM) with ultra-fast HF readout and 157 ps (FWHM) with the system-applicable TOFPET2 ASIC. Evaluating the timing limits of the scintillation material, we even show a CTR of 56 ps (FWHM) for small 2 × 2 × 3 mm3pixels. A complete overview of the timing performance obtained with different coatings (Teflon, BaSO4) and different crystal sizes coupled to standard Broadcom AFBR-S4N33C013 SiPMs will be presented and discussed.Significance.This work thoroughly evaluates commercially available co-doped LYSO:Ce crystals and, in combination with novel NUV-MT SiPMs, shows a TOF performance that significantly exceeds the current state of the art.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
| | - Katrin Herweg
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
| | | | - Jack W C Lin
- Taiwan Applied Crystal Co., LTD, Kaohsiung 80424, Taiwan
| | - Edmund Chin
- Taiwan Applied Crystal Co., LTD, Kaohsiung 80424, Taiwan
| | - Chu-An Li
- Center of Crystal Research, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, D-52074 Aachen, Germany
- Physics Institute IIIB, RWTH Aachen University, D-52074 Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, D-52074 Aachen, Germany
| | - Stefan Gundacker
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
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Naunheim S, Kuhl Y, Solf T, Schug D, Schulz V, Mueller F. Analysis of a convex time skew calibration for light sharing-based PET detectors. Phys Med Biol 2023; 68. [PMID: 36595338 DOI: 10.1088/1361-6560/aca872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 12/01/2022] [Indexed: 12/05/2022]
Abstract
Objective.Positron emission tomography (PET) detectors providing attractive coincidence time resolutions (CTRs) offer time-of-flight information, resulting in an improved signal-to-noise ratio of the PET image. In applications with photosensor arrays that employ timestampers for individual channels, timestamps typically are not time synchronized, introducing time skews due to different signal pathways. The scintillator topology and transportation of the scintillation light might provoke further skews. If not accounted for these effects, the achievable CTR deteriorates. We studied a convex timing calibration based on a matrix equation. In this work, we extended the calibration concept to arbitrary structures targeting different aspects of the time skews and focusing on optimizing the CTR performance for detector characterization. The radiation source distribution, the stability of the estimations, and the energy dependence of calibration data are subject to the analysis.Approach.A coincidence setup, equipped with a semi-monolithic detector comprising 8 LYSO slabs, each 3.9 mm × 31.9 mm × 19.0 mm, and a one-to-one coupled detector with 8 × 8 LYSO segments of 3.9 mm × 3.9 mm × 19.0 mm volume is used. Both scintillators utilize a dSiPM (DPC3200-22-44, Philips Digital Photon Counting) operated in first photon trigger. The calibration was also conducted with solely one-to-one coupled detectors and extrapolated for a slab-only setup.Main results.All analyzed hyperparameters show a strong influence on the calibration. Using multiple radiation positions improved the skew estimation. The statistical significance of the calibration dataset and the utilized energy window was of great importance. Compared to a one-to-one coupled detector pair achieving CTRs of 224 ps the slab detector configuration reached CTRs down to 222 ps, demonstrating that slabs can compete with a clinically used segmented detector design.Significance.This is the first work that systematically studies the influence of hyperparameters on skew estimation and proposes an extension to arbitrary calibration structures (e.g. scintillator volumes) of a known calibration technique.
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Affiliation(s)
- Stephan Naunheim
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Imaging, RWTH Aachen University, Germany
| | - Yannick Kuhl
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Imaging, RWTH Aachen University, Germany
| | - Torsten Solf
- Philips Digital Photon Counting, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Imaging, RWTH Aachen University, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Imaging, RWTH Aachen University, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany.,Physics Institute III B, RWTH Aachen University, Aachen, Germany
| | - Florian Mueller
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Imaging, RWTH Aachen University, Germany
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Herweg K, Nadig V, Schulz V, Gundacker S. On the prospects of BaF2 as a fast scintillator for time-of-flight positron emission tomography systems. IEEE Trans Radiat Plasma Med Sci 2023. [DOI: 10.1109/trpms.2023.3237254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Katrin Herweg
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Stefan Gundacker
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
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14
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Krueger K, Mueller F, Gebhardt P, Weissler B, Schug D, Schulz V. High-throughput FPGA-based Inference of Gradient Tree Boosting Models for Position Estimation in PET Detectors. IEEE Trans Radiat Plasma Med Sci 2023. [DOI: 10.1109/trpms.2023.3238904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Karl Krueger
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Florian Mueller
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Pierre Gebhardt
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Bjoern Weissler
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
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Khader F, Han T, Müller-Franzes G, Huck L, Schad P, Keil S, Barzakova E, Schulze-Hagen M, Pedersoli F, Schulz V, Zimmermann M, Nebelung L, Kather J, Hamesch K, Haarburger C, Marx G, Stegmaier J, Kuhl C, Bruners P, Nebelung S, Truhn D. Artificial Intelligence for Clinical Interpretation of Bedside Chest Radiographs. Radiology 2022; 307:e220510. [PMID: 36472534 DOI: 10.1148/radiol.220510] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background Supine chest radiography for bedridden patients in intensive care units (ICUs) is one of the most frequently ordered imaging studies worldwide. Purpose To evaluate the diagnostic performance of a neural network-based model that is trained on structured semiquantitative radiologic reports of bedside chest radiographs. Materials and Methods For this retrospective single-center study, children and adults in the ICU of a university hospital who had been imaged using bedside chest radiography from January 2009 to December 2020 were reported by using a structured and itemized template. Ninety-eight radiologists rated the radiographs semiquantitatively for the severity of disease patterns. These data were used to train a neural network to identify cardiomegaly, pulmonary congestion, pleural effusion, pulmonary opacities, and atelectasis. A held-out internal test set (100 radiographs from 100 patients) that was assessed independently by an expert panel of six radiologists provided the ground truth. Individual assessments by each of these six radiologists, by two nonradiologist physicians in the ICU, and by the neural network were compared with the ground truth. Separately, the nonradiologist physicians assessed the images without and with preliminary readings provided by the neural network. The weighted Cohen κ coefficient was used to measure agreement between the readers and the ground truth. Results A total of 193 566 radiographs in 45 016 patients (mean age, 66 years ± 16 [SD]; 61% men) were included and divided into training (n = 122 294; 64%), validation (n = 31 243; 16%), and test (n = 40 029; 20%) sets. The neural network exhibited higher agreement with a majority vote of the expert panel (κ = 0.86) than each individual radiologist compared with the majority vote of the expert panel (κ = 0.81 to ≤0.84). When the neural network provided preliminary readings, the reports of the nonradiologist physicians improved considerably (aided vs unaided, κ = 0.87 vs 0.79, respectively; P < .001). Conclusion A neural network trained with structured semiquantitative bedside chest radiography reports allowed nonradiologist physicians improved interpretations compared with the consensus reading of expert radiologists. © RSNA, 2022 Supplemental material is available for this article. See also the editorial by Wielpütz in this issue.
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Affiliation(s)
- Firas Khader
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Tianyu Han
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Gustav Müller-Franzes
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Luisa Huck
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Philipp Schad
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Sebastian Keil
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Emona Barzakova
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Maximilian Schulze-Hagen
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Federico Pedersoli
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Volkmar Schulz
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Markus Zimmermann
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Lina Nebelung
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Jakob Kather
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Karim Hamesch
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Christoph Haarburger
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Gernot Marx
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Johannes Stegmaier
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Christiane Kuhl
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Philipp Bruners
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Sven Nebelung
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
| | - Daniel Truhn
- From the Department of Diagnostic and Interventional Radiology (F.K., G.M.F., L.H., P.S., S.K., E.B., M.S.H., F.P., M.Z., C.K., P.B., S.N., D.T.), Department of Medicine III (J.K., K.H.), and Clinic for Surgical Intensive Medicine and Intermediate Care (G.M.), University Hospital Aachen, Pauwelsstrasse 30, 52064 Aachen, Germany; Physics of Molecular Imaging Systems, Experimental Molecular Imaging (T.H., V.S.), and Institute of Imaging and Computer Vision (J.S.), RWTH Aachen University, Aachen, Germany; Department of Inner Medicine, Luisenhospital Aachen, Aachen, Germany (L.N.); and Ocumeda AG, Erlen, Switzerland (C.H.)
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16
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Mueller F, Naunheim S, Kuhl Y, Schug D, Solf T, Schulz V. A semi-monolithic detector providing intrinsic DOI-encoding and sub-200 ps CRT TOF-capabilities for clinical PET applications. Med Phys 2022; 49:7469-7488. [PMID: 36259245 DOI: 10.1002/mp.16015] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/25/2022] [Accepted: 09/11/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Current clinical positron emission tomography (PET) systems utilize detectors where the scintillator typically contains single elements of 3-6-mm width and about 20-mm height. While providing good time-of-flight performance, this design limits the spatial resolution and causes radial astigmatism as the depth-of-interaction (DOI) remains unknown. PURPOSE We propose an alternative, aiming to combine the advantages of current detectors with the DOI capabilities shown for monolithic concepts, based on semi-monolithic scintillators (slabs). Here, the optical photons spread along one dimension enabling DOI-encoding with a still small readout area beneficial for timing performance. METHODS An array of eight monolithic LYSO slabs of dimensions 3.9 × 32 × 19 mm3 was read out by a 64-channel photosensor containing digital SiPMs (DPC3200-22-44, Philips Digital Photon Counting). The position estimation in the detector's monolithic and DOI direction was based on a calibration with a fan beam collimator and the machine learning technique gradient tree boosting (GTB). RESULTS We achieved a positioning performance in terms of mean absolute error (MAE) of 1.44 mm for the monolithic direction and 2.12 mm for DOI considering a wide energy window of 300-700 keV. The energy resolution was determined to be 11.3%, applying a positional-dependent energy calibration. We established both an analytical and machine-learning-based timing calibration approach and applied them for a first-photon trigger. The analytical timing calibration corrects for electronic and optical time skews leading to 240 ps coincidence resolving time (CRT) for a pair of slab-detectors. The CRT was significantly improved by utilizing GTB to predict the time difference based on specific training data and applied on top of the analytical calibration. We achieved 209 ps for the wide energy window and 198 ps for a narrow selection around the photopeak (411-561 keV). To maintain the detector's sensitivity, no filters were applied to the data during processing. CONCLUSION Overall, the semi-monolithic detector provides attractive performance characteristics. Especially, a good CRT can be achieved while introducing DOI capabilities to the detector, making the concept suitable for clinical PET scanners.
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Affiliation(s)
- Florian Mueller
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Stephan Naunheim
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Yannick Kuhl
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Torsten Solf
- Philips Digital Photon Counting (PDPC), Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany.,III. Institute of Physics B, RWTH Aachen University, Aachen, Germany
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17
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Pallares RM, Mottaghy FM, Schulz V, Kiessling F, Lammers T. Nanoparticle Diagnostics and Theranostics in the Clinic. J Nucl Med 2022; 63:1802-1808. [PMID: 36302654 PMCID: PMC9730918 DOI: 10.2967/jnumed.122.263895] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 10/19/2022] [Indexed: 01/11/2023] Open
Abstract
Nanoparticles possess unique features that may be useful for disease diagnosis and therapy. Preclinically, many different nanodiagnostics have been explored, but only a few have made it to the market. We here provide an overview of nanoparticle-based imaging agents currently used and evaluated in the clinic and discuss preclinical progress and translational avenues for the use of nanoparticles for diagnostic and theranostic applications.
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Affiliation(s)
- Roger M. Pallares
- Institute for Experimental Molecular Imaging, RWTH Aachen University Hospital, Aachen, Germany
| | - Felix M. Mottaghy
- Department of Nuclear Medicine, RWTH Aachen University Hospital, Aachen, Germany;,Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; and
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, RWTH Aachen University Hospital, Aachen, Germany;,Physics Institute III B, RWTH Aachen University, Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, RWTH Aachen University Hospital, Aachen, Germany
| | - Twan Lammers
- Institute for Experimental Molecular Imaging, RWTH Aachen University Hospital, Aachen, Germany
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18
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Ghaffari Laleh N, Truhn D, Veldhuizen GP, Han T, van Treeck M, Buelow RD, Langer R, Dislich B, Boor P, Schulz V, Kather JN. Adversarial attacks and adversarial robustness in computational pathology. Nat Commun 2022; 13:5711. [PMID: 36175413 PMCID: PMC9522657 DOI: 10.1038/s41467-022-33266-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 09/09/2022] [Indexed: 11/09/2022] Open
Abstract
Artificial Intelligence (AI) can support diagnostic workflows in oncology by aiding diagnosis and providing biomarkers directly from routine pathology slides. However, AI applications are vulnerable to adversarial attacks. Hence, it is essential to quantify and mitigate this risk before widespread clinical use. Here, we show that convolutional neural networks (CNNs) are highly susceptible to white- and black-box adversarial attacks in clinically relevant weakly-supervised classification tasks. Adversarially robust training and dual batch normalization (DBN) are possible mitigation strategies but require precise knowledge of the type of attack used in the inference. We demonstrate that vision transformers (ViTs) perform equally well compared to CNNs at baseline, but are orders of magnitude more robust to white- and black-box attacks. At a mechanistic level, we show that this is associated with a more robust latent representation of clinically relevant categories in ViTs compared to CNNs. Our results are in line with previous theoretical studies and provide empirical evidence that ViTs are robust learners in computational pathology. This implies that large-scale rollout of AI models in computational pathology should rely on ViTs rather than CNN-based classifiers to provide inherent protection against perturbation of the input data, especially adversarial attacks. Artificial Intelligence can support diagnostic workflows in oncology, but they are vulnerable to adversarial attacks. Here, the authors show that convolutional neural networks are highly susceptible to white- and black-box adversarial attacks in clinically relevant classification tasks.
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Affiliation(s)
- Narmin Ghaffari Laleh
- Department of Medicine III, University Hospital RWTH Aachen, RWTH Aachen university, Aachen, Germany
| | - Daniel Truhn
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
| | - Gregory Patrick Veldhuizen
- Else Kroener Fresenius Center for Digital Health, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden, Germany
| | - Tianyu Han
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Marko van Treeck
- Department of Medicine III, University Hospital RWTH Aachen, RWTH Aachen university, Aachen, Germany
| | - Roman D Buelow
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Rupert Langer
- Institute of Pathology, University of Bern, Bern, Switzerland.,Institute of Pathology and Molecular Pathology, Kepler University Hospital, Johannes Kepler University Linz, Linz, Austria
| | - Bastian Dislich
- Institute of Pathology, University of Bern, Bern, Switzerland
| | - Peter Boor
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Physics Institute III B, RWTH Aachen University, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Jakob Nikolas Kather
- Department of Medicine III, University Hospital RWTH Aachen, RWTH Aachen university, Aachen, Germany. .,Else Kroener Fresenius Center for Digital Health, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden, Germany. .,Medical Oncology, National Center for Tumor Diseases (NCT), University Hospital Heidelberg, Heidelberg, Germany. .,Division of Pathology and Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK. .,Department of Medicine 1, University Hospital and Faculty of Medicine Carl Gustav Carus, Technical University Dresden, Dresden, Germany.
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19
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Ghaffari Laleh N, Muti HS, Loeffler CML, Echle A, Saldanha OL, Mahmood F, Lu MY, Trautwein C, Langer R, Dislich B, Buelow RD, Grabsch HI, Brenner H, Chang-Claude J, Alwers E, Brinker TJ, Khader F, Truhn D, Gaisa NT, Boor P, Hoffmeister M, Schulz V, Kather JN. Erratum to 'Benchmarking weakly-supervised deep learning pipelines for whole slide classification in computational pathology' Medical Image Analysis, Volume 79, July 2022, 102474. Med Image Anal 2022; 82:102622. [PMID: 36130464 DOI: 10.1016/j.media.2022.102622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | - Hannah Sophie Muti
- Department of Medicine III, University Hospital RWTH Aachen, Aachen, Germany
| | | | - Amelie Echle
- Department of Medicine III, University Hospital RWTH Aachen, Aachen, Germany
| | | | - Faisal Mahmood
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ming Y Lu
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Christian Trautwein
- Department of Medicine III, University Hospital RWTH Aachen, Aachen, Germany
| | - Rupert Langer
- Institute of Pathology and Molecular Pathology, Kepler University Hospital, Johannes Kepler University Linz, Linz, Austria
| | | | - Roman D Buelow
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Heike Irmgard Grabsch
- Department of Pathology, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center+, Maastricht, The Netherlands.; Division of Pathology and Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK
| | - Hermann Brenner
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany; Division of Preventive Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany; German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Jenny Chang-Claude
- Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Cancer Epidemiology Group, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Elizabeth Alwers
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Titus J Brinker
- Digital Biomarkers for Oncology Group, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Firas Khader
- Department of Radiology, University Hospital RWTH Aachen, Aachen, Germany
| | - Daniel Truhn
- Department of Radiology, University Hospital RWTH Aachen, Aachen, Germany
| | - Nadine T Gaisa
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Peter Boor
- Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Michael Hoffmeister
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany; Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany; Comprehensive Diagnostic Center Aachen (CDCA), University Hospital Aachen, Aachen, Germany; Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Jakob Nikolas Kather
- Department of Medicine III, University Hospital RWTH Aachen, Aachen, Germany; Division of Pathology and Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK; Else Kroener Fresenius Center for Digital Health, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden, Germany.
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20
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Pantke D, Mueller F, Reinartz S, Philipps J, Mohammadali Dadfar S, Peters M, Franke J, Schrank F, Kiessling F, Schulz V. Frequency-selective signal enhancement by a passive dual coil resonator for magnetic particle imaging. Phys Med Biol 2022; 67. [PMID: 35472698 DOI: 10.1088/1361-6560/ac6a9f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 04/26/2022] [Indexed: 11/12/2022]
Abstract
Objective.Magnetic particle imaging (MPI) visualizes the spatial distribution of magnetic nanoparticles. MPI already provides excellent temporal and good spatial resolution, however, to achieve translation into clinics, further advances in the fields of sensitivity, image reconstruction and tracer performance are needed. In this work, we propose a novel concept to enhance the MPI signal and image resolution by a purely passive receive coil insert for a preclinical MPI system.Approach.The passive dual coil resonator (pDCR) provides frequency-selective signal enhancement. This is enabled by the adaptable resonance frequency of the pDCR network, which is galvanically isolated from the MPI system and composed of two coaxial solenoids connected via a capacitor. The pDCR aims to enhance frequency components related to high mixing orders, which are crucial to achieve high spatial resolution.Main Results.In this study, system matrix measurements and image acquisitions of a resolution phantom are carried out to evaluate the performance of the pDCR compared to the integrated receive unit of the preclinical MPI and a dedicated rat-sized receive coil. Frequency-selective signal increase and spatial resolution enhancement are demonstrated.Significance.Common dedicated receive coils come along with noise-matched receive networks, which makes them costly and difficult to reproduce. The presented pDCR is a purely passive coil insert that gets along without any additional receive electronics. Therefore, it is cost-efficient, easy-to-handle and adaptable to other MPI scanners and potentially other applications providing the basis for a new breed of passive MPI receiver systems.
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Affiliation(s)
- Dennis Pantke
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Florian Mueller
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Sebastian Reinartz
- Department of Diagnostic and Interventional Radiology, Uniklinik RWTH Aachen, Aachen, Germany
| | - Jonas Philipps
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Seyed Mohammadali Dadfar
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Maximilian Peters
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Jochen Franke
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Bruker BioSpin MRI GmbH, Preclinical Imaging Division, Ettlingen, Germany
| | - Franziska Schrank
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany.,III. Physikalisches Institut B, RWTH Aachen University, Aachen, Germany
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21
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Kiessling F, Schulz V. Perspectives of Evidence-Based Therapy Management. ROFO-FORTSCHR RONTG 2022; 194:728-736. [PMID: 35545101 DOI: 10.1055/a-1752-0839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Therapeutics that specifically address biological processes often require a much finer selection of patients and subclassification of diseases. Thus, diagnostic procedures must describe the diseases in sufficient detail to allow selection of appropriate therapy and to sensitively track therapy response. Anatomical features are often not sufficient for this purpose and there is a need to image molecular and pathophysiological processes. METHOD Two imaging strategies can be pursued: molecular imaging attempts to image a few biomarkers that play key roles in pathological processes. Alternatively, patterns describing a biological process can be identified from the synopsis of multiple (non-specific) imaging markers, possibly in combination with omics and other clinical findings. Here, AI-based methods are increasingly being used. RESULTS Both strategies of evidence-based therapy management are explained in this review article and examples and clinical successes are presented. In this context, reviews of clinically approved molecular diagnostics and decision support systems are listed. Furthermore, since reliable, representative, and sufficiently large datasets are further important prerequisites for AI-assisted multiparametric analyses, concepts are presented to make data available in a structured way, e. g., using Generative Adversarial Networks to complement databases with virtual cases and to build completely anonymous reference databases. CONCLUSION Molecular imaging and computer-assisted cluster analysis of diagnostic data are complementary methods to describe pathophysiological processes. Both methods have the potential to improve (evidence-based) the future management of therapies, partly on their own but also in combined approaches. KEY POINTS · Molecular imaging and radiomics provide valuable complementary disease biomarkers.. · Data-driven, model-based, and hybrid model-based integrated diagnostics advance precision medicine.. · Synthetic data generation may become essential in the development process of future AI methods.. CITATION FORMAT · Kiessling F, Schulz V, . Perspectives of Evidence-Based Therapy Management. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1752-0839.
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Affiliation(s)
- Fabian Kiessling
- Universitätsklinikum Aachen, Lehrstuhl für Experimentelle Molekulare Bildgebung, Aachen, Germany.,Group Aachen, Fraunhofer-Institut für Digitale Medizin MEVIS, Bremen, Germany
| | - Volkmar Schulz
- Universitätsklinikum Aachen, Lehrstuhl für Experimentelle Molekulare Bildgebung, Aachen, Germany.,Group Aachen, Fraunhofer-Institut für Digitale Medizin MEVIS, Bremen, Germany
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22
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Laleh NG, Muti HS, Loeffler CML, Echle A, Saldanha OL, Mahmood F, Lu MY, Trautwein C, Langer R, Dislich B, Buelow RD, Grabsch HI, Brenner H, Chang-Claude J, Alwers E, Brinker TJ, Khader F, Truhn D, Gaisa NT, Boor P, Hoffmeister M, Schulz V, Kather JN. Benchmarking weakly-supervised deep learning pipelines for whole slide classification in computational pathology. Med Image Anal 2022; 79:102474. [DOI: 10.1016/j.media.2022.102474] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 04/07/2022] [Accepted: 05/03/2022] [Indexed: 02/07/2023]
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23
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Pathak V, Roemhild K, Schipper S, Groß-Weege N, Nolte T, Ruetten S, Buhl EM, El Shafei A, Weiler M, Martin L, Marx G, Schulz V, Kiessling F, Lammers T, Koczera P. Theranostic Trigger-Responsive Carbon Monoxide-Generating Microbubbles. Small 2022; 18:e2200924. [PMID: 35363403 DOI: 10.1002/smll.202200924] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Carbon monoxide (CO) is a gaseous signaling molecule that modulates inflammation, cell survival, and recovery after myocardial infarction. However, handling and dosing of CO as a compressed gas are difficult. Here, light-triggerable and magnetic resonance imaging (MRI)-detectable CO release from dimanganese decacarbonyl (CORM-1) are demonstrated, and the development of CORM-1-loaded polymeric microbubbles (COMB) is described as an ultrasound (US)- and MRI-imageable drug delivery platform for triggerable and targeted CO therapy. COMB are synthesized via a straightforward one-step loading protocol, present a narrow size distribution peaking at 2 µm, and show excellent performance as a CORM-1 carrier and US contrast agent. Light irradiation of COMB induces local production and release of CO, as well as enhanced longitudinal and transversal relaxation rates, enabling MRI monitoring of CO delivery. Proof-of-concept studies for COMB-enabled light-triggered CO release show saturation of hemoglobin with CO in human blood, anti-inflammatory differentiation of macrophages, reduction of hypoxia-induced reactive oxygen species (ROS) production, and inhibition of ischemia-induced apoptosis in endothelial cells and cardiomyocytes. These findings indicate that CO-generating MB are interesting theranostic tools for attenuating hypoxia-associated and ROS-mediated cell and tissue damage in cardiovascular disease.
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Affiliation(s)
- Vertika Pathak
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Karolin Roemhild
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
- Institute of Pathology, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Sandra Schipper
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
- Department of General, Visceral and Transplantation Surgery, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Nicolas Groß-Weege
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Teresa Nolte
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Stephan Ruetten
- Electron Microscopy, Institute of Pathology, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Eva Miriam Buhl
- Electron Microscopy, Institute of Pathology, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Asmaa El Shafei
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Marek Weiler
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Lukas Martin
- Department of Intensive Care Medicine, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Gernot Marx
- Department of Intensive Care Medicine, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
| | - Twan Lammers
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
- Department of Pharmaceutics, Utrecht University, Utrecht, 3584CG, The Netherlands
- Department of Targeted Therapeutics, University of Twente, Enschede, 7522 NB, The Netherlands
| | - Patrick Koczera
- Institute for Experimental Molecular Imaging, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
- Department of Intensive Care Medicine, Medical Faculty, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Clinic, 52074, Aachen, Germany
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24
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Rama E, Mohapatra SR, Melcher C, Nolte T, Dadfar SM, Brueck R, Pathak V, Rix A, Gries T, Schulz V, Lammers T, Apel C, Jockenhoevel S, Kiessling F. Monitoring the Remodeling of Biohybrid Tissue-Engineered Vascular Grafts by Multimodal Molecular Imaging. Adv Sci (Weinh) 2022; 9:e2105783. [PMID: 35119216 PMCID: PMC8981893 DOI: 10.1002/advs.202105783] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Indexed: 06/10/2023]
Abstract
Tissue-engineered vascular grafts (TEVGs) with the ability to grow and remodel open new perspectives for cardiovascular surgery. Equipping TEVGs with synthetic polymers and biological components provides a good compromise between high structural stability and biological adaptability. However, imaging approaches to control grafts' structural integrity, physiological function, and remodeling during the entire transition between late in vitro maturation and early in vivo engraftment are mandatory for clinical implementation. Thus, a comprehensive molecular imaging concept using magnetic resonance imaging (MRI) and ultrasound (US) to monitor textile scaffold resorption, extracellular matrix (ECM) remodeling, and endothelial integrity in TEVGs is presented here. Superparamagnetic iron-oxide nanoparticles (SPION) incorporated in biodegradable poly(lactic-co-glycolic acid) (PLGA) fibers of the TEVGs allow to quantitatively monitor scaffold resorption via MRI both in vitro and in vivo. Additionally, ECM formation can be depicted by molecular MRI using elastin- and collagen-targeted probes. Finally, molecular US of αv β3 integrins confirms the absence of endothelial dysfunction; the latter is provocable by TNF-α. In conclusion, the successful employment of noninvasive molecular imaging to longitudinally evaluate TEVGs remodeling is demonstrated. This approach may foster its translation from in vitro quality control assessment to in vivo applications to ensure proper prostheses engraftment.
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Affiliation(s)
- Elena Rama
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Saurav Ranjan Mohapatra
- Department of Biohybrid & Medical TextilesInstitute of Applied Medical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Christoph Melcher
- Institute for Textile Technology RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Teresa Nolte
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Seyed Mohammadali Dadfar
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Ramona Brueck
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Vertika Pathak
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Anne Rix
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Thomas Gries
- Institute for Textile Technology RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Twan Lammers
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Christian Apel
- Department of Biohybrid & Medical TextilesInstitute of Applied Medical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Stefan Jockenhoevel
- Department of Biohybrid & Medical TextilesInstitute of Applied Medical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH – Aachen University Forckenbeckstrasse 5552074AachenGermany
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25
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Magnuska ZA, Theek B, Darguzyte M, Palmowski M, Stickeler E, Schulz V, Kießling F. Influence of the Computer-Aided Decision Support System Design on Ultrasound-Based Breast Cancer Classification. Cancers (Basel) 2022; 14:277. [PMID: 35053441 PMCID: PMC8773857 DOI: 10.3390/cancers14020277] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 12/30/2021] [Indexed: 02/04/2023] Open
Abstract
Automation of medical data analysis is an important topic in modern cancer diagnostics, aiming at robust and reproducible workflows. Therefore, we used a dataset of breast US images (252 malignant and 253 benign cases) to realize and compare different strategies for CAD support in lesion detection and classification. Eight different datasets (including pre-processed and spatially augmented images) were prepared, and machine learning algorithms (i.e., Viola-Jones; YOLOv3) were trained for lesion detection. The radiomics signature (RS) was derived from detection boxes and compared with RS derived from manually obtained segments. Finally, the classification model was established and evaluated concerning accuracy, sensitivity, specificity, and area under the Receiver Operating Characteristic curve. After training on a dataset including logarithmic derivatives of US images, we found that YOLOv3 obtains better results in breast lesion detection (IoU: 0.544 ± 0.081; LE: 0.171 ± 0.009) than the Viola-Jones framework (IoU: 0.399 ± 0.054; LE: 0.096 ± 0.016). Interestingly, our findings show that the classification model trained with RS derived from detection boxes and the model based on the RS derived from a gold standard manual segmentation are comparable (p-value = 0.071). Thus, deriving radiomics signatures from the detection box is a promising technique for building a breast lesion classification model, and may reduce the need for the lesion segmentation step in the future design of CAD systems.
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Affiliation(s)
- Zuzanna Anna Magnuska
- Institute for Experimental Molecular Imaging, Uniklinik RWTH Aachen and Helmholtz Institute for Biomedical Engineering, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany; (Z.A.M.); (B.T.); (M.D.); (V.S.)
| | - Benjamin Theek
- Institute for Experimental Molecular Imaging, Uniklinik RWTH Aachen and Helmholtz Institute for Biomedical Engineering, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany; (Z.A.M.); (B.T.); (M.D.); (V.S.)
| | - Milita Darguzyte
- Institute for Experimental Molecular Imaging, Uniklinik RWTH Aachen and Helmholtz Institute for Biomedical Engineering, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany; (Z.A.M.); (B.T.); (M.D.); (V.S.)
| | - Moritz Palmowski
- Radiologie Baden-Baden, Beethovenstraße 2, 76530 Baden-Baden, Germany;
| | - Elmar Stickeler
- Department of Obstetrics and Gynecology, University Clinic Aachen, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany;
- Comprehensive Diagnostic Center Aachen, Uniklinik RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, Uniklinik RWTH Aachen and Helmholtz Institute for Biomedical Engineering, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany; (Z.A.M.); (B.T.); (M.D.); (V.S.)
- Comprehensive Diagnostic Center Aachen, Uniklinik RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
- Physics Institute III B, RWTH Aachen University, 52074 Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, 52074 Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Am Fallturm 1, 28359 Bremen, Germany
| | - Fabian Kießling
- Institute for Experimental Molecular Imaging, Uniklinik RWTH Aachen and Helmholtz Institute for Biomedical Engineering, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany; (Z.A.M.); (B.T.); (M.D.); (V.S.)
- Comprehensive Diagnostic Center Aachen, Uniklinik RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Am Fallturm 1, 28359 Bremen, Germany
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26
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Nadig V, Herrmann K, Mottaghy FM, Schulz V. Hybrid total-body pet scanners-current status and future perspectives. Eur J Nucl Med Mol Imaging 2022; 49:445-459. [PMID: 34647154 PMCID: PMC8803785 DOI: 10.1007/s00259-021-05536-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 08/20/2021] [Indexed: 12/18/2022]
Abstract
Purpose Since the 1990s, PET has been successfully combined with MR or CT systems. In the past years, especially PET systems have seen a trend towards an enlarged axial field of view (FOV), up to a factor of ten. Methods Conducting a thorough literature research, we summarize the status quo of contemporary total-body (TB) PET/CT scanners and give an outlook on possible future developments. Results Currently, three human TB PET/CT systems have been developed: The PennPET Explorer, the uExplorer, and the Biograph Vision Quadra realize aFOVs between 1 and 2 m and show a tremendous increase in system sensitivity related to their longer gantries. Conclusion The increased system sensitivity paves the way for short-term, low-dose, and dynamic TB imaging as well as new examination methods in almost all areas of imaging.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, University of Duisburg-Essen, Duisburg, Germany
- German Cancer Consortium (DKTK) - University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Felix M Mottaghy
- Department of Nuclear Medicine, University Hospital Aachen, RWTH Aachen University, Aachen, Germany
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.
- Physics Institute III B, RWTH Aachen University, Aachen, Germany.
- Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany.
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27
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Nadig V, Yusopova M, Radermacher H, Schug D, Weissler B, Schulz V, Gundacker S. A comprehensive study on the timing limits of the TOFPET2 ASIC and on approaches for improvements. IEEE Trans Radiat Plasma Med Sci 2022. [DOI: 10.1109/trpms.2022.3158704] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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28
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Schrammen PL, Ghaffari Laleh N, Echle A, Truhn D, Schulz V, Brinker TJ, Brenner H, Chang-Claude J, Alwers E, Brobeil A, Kloor M, Heij LR, Jäger D, Trautwein C, Grabsch HI, Quirke P, West NP, Hoffmeister M, Kather JN. Weakly supervised annotation-free cancer detection and prediction of genotype in routine histopathology. J Pathol 2021; 256:50-60. [PMID: 34561876 DOI: 10.1002/path.5800] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 08/01/2021] [Accepted: 09/03/2021] [Indexed: 12/17/2022]
Abstract
Deep learning is a powerful tool in computational pathology: it can be used for tumor detection and for predicting genetic alterations based on histopathology images alone. Conventionally, tumor detection and prediction of genetic alterations are two separate workflows. Newer methods have combined them, but require complex, manually engineered computational pipelines, restricting reproducibility and robustness. To address these issues, we present a new method for simultaneous tumor detection and prediction of genetic alterations: The Slide-Level Assessment Model (SLAM) uses a single off-the-shelf neural network to predict molecular alterations directly from routine pathology slides without any manual annotations, improving upon previous methods by automatically excluding normal and non-informative tissue regions. SLAM requires only standard programming libraries and is conceptually simpler than previous approaches. We have extensively validated SLAM for clinically relevant tasks using two large multicentric cohorts of colorectal cancer patients, Darmkrebs: Chancen der Verhütung durch Screening (DACHS) from Germany and Yorkshire Cancer Research Bowel Cancer Improvement Programme (YCR-BCIP) from the UK. We show that SLAM yields reliable slide-level classification of tumor presence with an area under the receiver operating curve (AUROC) of 0.980 (confidence interval 0.975, 0.984; n = 2,297 tumor and n = 1,281 normal slides). In addition, SLAM can detect microsatellite instability (MSI)/mismatch repair deficiency (dMMR) or microsatellite stability/mismatch repair proficiency with an AUROC of 0.909 (0.888, 0.929; n = 2,039 patients) and BRAF mutational status with an AUROC of 0.821 (0.786, 0.852; n = 2,075 patients). The improvement with respect to previous methods was validated in a large external testing cohort in which MSI/dMMR status was detected with an AUROC of 0.900 (0.864, 0.931; n = 805 patients). In addition, SLAM provides human-interpretable visualization maps, enabling the analysis of multiplexed network predictions by human experts. In summary, SLAM is a new simple and powerful method for computational pathology that could be applied to multiple disease contexts. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
| | | | - Amelie Echle
- Department of Medicine III, University Hospital RWTH Aachen, Aachen, Germany
| | - Daniel Truhn
- Department of Radiology, University Hospital RWTH Aachen, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany.,Comprehensive Diagnostic Center Aachen (CDCA), University Hospital Aachen, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Titus J Brinker
- Digital Biomarkers for Oncology Group, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Hermann Brenner
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Division of Preventive Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany.,German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Jenny Chang-Claude
- Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Cancer Epidemiology Group, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Elizabeth Alwers
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Alexander Brobeil
- Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.,Tumor Bank Unit, Tissue Bank of the National Center for Tumor Diseases, Heidelberg, Germany
| | - Matthias Kloor
- Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany
| | - Lara R Heij
- Department of Pathology, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center+, Maastricht, The Netherlands.,Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany.,Department of Surgery and Transplantation, University Hospital RWTH Aachen, Aachen, Germany
| | - Dirk Jäger
- Medical Oncology, National Center of Tumor Diseases (NCT), University Hospital Heidelberg, Heidelberg, Germany
| | - Christian Trautwein
- Department of Medicine III, University Hospital RWTH Aachen, Aachen, Germany
| | - Heike I Grabsch
- Department of Pathology, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center+, Maastricht, The Netherlands.,Pathology & Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK
| | - Philip Quirke
- Pathology & Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK
| | - Nicholas P West
- Pathology & Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK
| | - Michael Hoffmeister
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Jakob Nikolas Kather
- Department of Medicine III, University Hospital RWTH Aachen, Aachen, Germany.,German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany.,Medical Oncology, National Center of Tumor Diseases (NCT), University Hospital Heidelberg, Heidelberg, Germany.,Pathology & Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK
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29
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Wassermann C, Mueller F, Dey T, Lambertus J, Schug D, Schulz V, Miller J. High throughput software-based gradient tree boosting positioning for PET systems. Biomed Phys Eng Express 2021; 7. [PMID: 34229316 DOI: 10.1088/2057-1976/ac11c0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/06/2021] [Indexed: 11/12/2022]
Abstract
The supervised machine learning technique Gradient Tree Boosting (GTB) has shown good accuracy for position estimation of gamma interaction in PET crystals for bench-top experiments while its computational requirements can easily be adjusted. Transitioning to preclinical and clinical applications requires near real-time processing in the scale of full PET systems. In this work, a high throughput GTB-based singles positioning C++ implementation is proposed and a series of optimizations are evaluated regarding their effect on the achievable processing throughput. Moreover, the crucial feature and parameter selection for GTB is investigated for the segmented detectors of the Hyperion IIDPET insert with two main models and a range of GTB hyperparameters. The proposed framework achieves singles positioning throughputs of more than 9.5 GB/s for smaller models and of 240 MB/s for more complex models on a recent Intel Skylake server. Detailed throughput analysis reveals the key performance limiting factors, and an empirical throughput model is derived to guide the GTB model selection process and scanner design decisions. The throughput model allows for throughput estimations with a mean absolute error (MAE) of 175.78 MB/s.
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Affiliation(s)
- Christian Wassermann
- High Performance Computing Group, Computational Science and Engineering Division, IT Center, RWTH Aachen University, 52074 Aachen, Germany
| | - Florian Mueller
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074 Aachen, Germany
| | - Thomas Dey
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074 Aachen, Germany.,Faculty 05 Electrical Engineering and Information Technology, FH Aachen University of Applied Sciences, 52074 Aachen, Germany
| | - Janko Lambertus
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074 Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074 Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, 52074 Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074 Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, 52074 Aachen, Germany.,Physics Institute III B, RWTH Aachen University, 52074 Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, 52074 Aachen, Germany
| | - Julian Miller
- High Performance Computing Group, Computational Science and Engineering Division, IT Center, RWTH Aachen University, 52074 Aachen, Germany
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Nolte T, Vaidya N, Baragona M, Elevelt A, Lavezzo V, Maessen R, Schulz V, Veroy K. Study of flow effects on temperature-controlled radiofrequency ablation using phantom experiments and forward simulations. Med Phys 2021; 48:4754-4768. [PMID: 34320224 DOI: 10.1002/mp.15138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 05/24/2021] [Accepted: 07/16/2021] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Blood flow is known to add variability to hepatic radiofrequency ablation (RFA) treatment outcomes. However, few studies exist on its impact on temperature-controlled RFA. Hence, we investigate large-scale blood flow effects on temperature-controlled RFA in flow channel experiments and numerical simulations. METHODS Ablation zones were induced in tissue-mimicking, thermochromic phantoms with a single flow channel, using an RF generator with temperature-controlled power delivery and a monopolar needle electrode. Channels were generated by molding the phantom around a removable rod. Channel radius and saline flow rate were varied to study the impact of flow on (i) the ablated cross-sectional area, (ii) the delivered generator power, and (iii) the occurrence of directional effects on the thermal lesion. Finite volume simulations reproducing the experimental geometry, flow conditions, and generator power input were conducted and compared to the experimental ablation outcomes. RESULTS Vessels of different channel radii r affected the ablation outcome in different ways. For r = 0.275 mm, the ablated area decreased with increasing flow rate while the energy input was hardly affected. For r = 0.9 mm and r = 2.3 mm, the energy input increased toward larger flow rates; for these radii, the ablated area decreased and increased toward larger flow rates, respectively, while still being reduced overall as compared to the reference experiment without flow. Directional effects, that is, local shrinking of the lesion upstream of the needle and an extension thereof downstream, were observed only for the smallest radius. The simulations qualitatively confirmed these observations. As compared to performing the simulations without flow, including flow effects in the simulations reduced the mean absolute error between experimental and simulated ablated areas from 0.23 to 0.12. CONCLUSION While the temperature control mechanism did not detect the heat sink effect in the case of the smallest channel radius, it counteracted the heat sink effect in the case of the larger channel radii with an increased energy input; this explains the increase in ablated area toward high flow rates (for r = 2.3 mm). The experiments in a simple phantom setup, thus, contribute to a good understanding of the phenomenon and are suitable for model validation.
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Affiliation(s)
- Teresa Nolte
- Department of Physics of Molecular Imaging systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Nikhil Vaidya
- Faculty of Civil Engineering, RWTH Aachen University, Aachen, Germany
| | | | | | | | | | - Volkmar Schulz
- Department of Physics of Molecular Imaging systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.,Physics Institute III B, RWTH Aachen University, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
| | - Karen Veroy
- Center for Analysis, Scientific Computing, and Applications, Eindhoven University of Technology, Eindhoven, The Netherlands
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Han T, Nebelung S, Pedersoli F, Zimmermann M, Schulze-Hagen M, Ho M, Haarburger C, Kiessling F, Kuhl C, Schulz V, Truhn D. Advancing diagnostic performance and clinical usability of neural networks via adversarial training and dual batch normalization. Nat Commun 2021; 12:4315. [PMID: 34262044 PMCID: PMC8280105 DOI: 10.1038/s41467-021-24464-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 06/17/2021] [Indexed: 11/09/2022] Open
Abstract
Unmasking the decision making process of machine learning models is essential for implementing diagnostic support systems in clinical practice. Here, we demonstrate that adversarially trained models can significantly enhance the usability of pathology detection as compared to their standard counterparts. We let six experienced radiologists rate the interpretability of saliency maps in datasets of X-rays, computed tomography, and magnetic resonance imaging scans. Significant improvements are found for our adversarial models, which are further improved by the application of dual-batch normalization. Contrary to previous research on adversarially trained models, we find that accuracy of such models is equal to standard models, when sufficiently large datasets and dual batch norm training are used. To ensure transferability, we additionally validate our results on an external test set of 22,433 X-rays. These findings elucidate that different paths for adversarial and real images are needed during training to achieve state of the art results with superior clinical interpretability.
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Affiliation(s)
- Tianyu Han
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
| | - Sven Nebelung
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
| | - Federico Pedersoli
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
| | - Markus Zimmermann
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
| | - Maximilian Schulze-Hagen
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
| | | | | | - Fabian Kiessling
- The Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany.,Comprehensive Diagnostic Center Aachen (CDCA), University Hospital RWTH Aachen, Aachen, Germany
| | - Christiane Kuhl
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
| | - Volkmar Schulz
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany. .,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany. .,Comprehensive Diagnostic Center Aachen (CDCA), University Hospital RWTH Aachen, Aachen, Germany.
| | - Daniel Truhn
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany.
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Pathak V, Nolte T, Rama E, Rix A, Dadfar SM, Paefgen V, Banala S, Buhl EM, Weiler M, Schulz V, Lammers T, Kiessling F. Molecular magnetic resonance imaging of Alpha-v-Beta-3 integrin expression in tumors with ultrasound microbubbles. Biomaterials 2021; 275:120896. [PMID: 34090049 DOI: 10.1016/j.biomaterials.2021.120896] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022]
Abstract
Microbubbles (MB) are used as ultrasound (US) contrast agents and can be efficiently targeted against markers of angiogenesis and inflammation. Due to their gas core, MB locally alter susceptibilities in magnetic resonance imaging (MRI), but unfortunately, the resulting contrast is low and not sufficient to generate powerful molecular MRI probes. Therefore, we investigated whether a potent molecular MR agent can be generated by encapsulating superparamagnetic iron oxide nanoparticles (SPION) in the polymeric shell of poly (n-butylcyanoacrylate) (PBCA) MB and targeted them against αvβ3 integrins on the angiogenic vasculature of 4T1 murine breast carcinomas. SPION-MB consist of an air core and a multi-layered polymeric shell enabling efficient entrapment of SPION. The mean size of SPION-MB was 1.61 ± 0.32 μm. Biotin-streptavidin coupling was employed to functionalize the SPION-MB with cyclic RGDfK (Arg-Gly-Asp) and RADfK (Arg-Ala-Asp) peptides. Cells incubated with RGD-SPION-MB showed enhanced transverse relaxation rates compared with SPION-MB and blocking αvβ3 integrin receptors with excess free cRGDfK significantly reduced RGD-SPION-MB binding. Due to the fast binding of RGD-SPION-MB in vivo, dynamic susceptibility contrast MRI was employed to track their retention in tumors in real-time. Higher retention of RGD-SPION-MB was observed compared with SPION-MB and RAD-SPION-MB. To corroborate our MRI results, molecular US was performed the following day using the destruction-replenishment method. Both imaging modalities consistently indicated higher retention of RGD-SPION-MB in angiogenic vessels compared with SPION-MB and RAD-SPION-MB. Competitive blocking experiments in mice further confirmed that the binding of RGD-SPION-MB to αvβ3 integrin receptors is specific. Overall, this study demonstrates that RGD-SPION-MB can be employed as molecular MR/US contrast agents and are capable of assessing the αvβ3 integrin expression in the neovasculature of malignant tumors.
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Affiliation(s)
- Vertika Pathak
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Teresa Nolte
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Elena Rama
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Anne Rix
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | | | - Vera Paefgen
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Srinivas Banala
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Eva Miriam Buhl
- Electron Microscope Facility, University Hospital RWTH, RWTH Aachen University, 52074, Aachen, Germany
| | - Marek Weiler
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Twan Lammers
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074, Aachen, Germany.
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Yin L, Schrank F, Gross-Weege N, Schug D, Schulz V. RF shielding materials for highly-integrated PET/MRI systems. Phys Med Biol 2021; 66. [PMID: 33831853 DOI: 10.1088/1361-6560/abf606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 04/08/2021] [Indexed: 11/12/2022]
Abstract
Integration of magnetic resonance imaging (MRI) and positron emission tomography (PET) into a simultaneous device calls for adaptations of the radio frequency (RF) shielding concept. Conventional PET module housings fully encase the entire PET detector to reduce mutual interference. Excluding passive components, i.e. scintillators, from the housings, offers integration advantages, e.g. by reducing the overall housing volume or utilizing bigger scintillators. However, locating the scintillator outside of the RF shielding requires an optically transparent RF shielding interface between the scintillators and the photodetector to close the aperture. Therefore, a careful evaluation and selection of RF materials is essential to ensure an excellent PET/MRI system performance. To this end, we examined 10 materials (coated glasses, coated foils, meshes). The shielding effectiveness (SE) was evaluated at 100 and 300 MHz. PET performance was tested for single event registration and coincident events by integrating the material into the PET detector stack between the digital silicon photomultiplier photodetector array and one-to-one coupled scintillator. We determined photon attenuation (PA), energy resolution (dE/E), and coincidence resolving time (CRT) and compared to reference measurements for each material group. MRI compatibility was assessed by analyzing the material influence on the main magnetic field (B0) homogeneity. The coated glasses and foils exhibited SEs of up to 25 dB at 300 MHz. Both had a PA < 23% with dE/E and CRT comparable to the reference measurements, and no measurable impact on the B0field was registered. The meshes exhibited higher SEs up to 56 dB, but also a PA > 58% with a higher impact on dE/E and CRT. Only one mesh affected B0homogeneity. Overall, we recommend the coated foil HS 9400 for integration concepts as it exhibited a good performance with SE = 25 dB, PA = 22%, resulting in a PET performance of dE/E = 12% and CRT = 274 ps.
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Affiliation(s)
- Laiyin Yin
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Franziska Schrank
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Nicolas Gross-Weege
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.,Physics Institute III B, RWTH Aachen University, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany
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Siepmann R, Nilius H, Mueller F, Mueller K, Luisi C, Dadfar SM, Straub M, Schulz V, Reinartz SD. Image-derived mean velocity measurement for prediction of coronary flow reserve in a canonical stenosis phantom using magnetic particle imaging. PLoS One 2021; 16:e0249697. [PMID: 33886607 PMCID: PMC8061921 DOI: 10.1371/journal.pone.0249697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 03/24/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Aim of this study is to evaluate whether magnetic particle imaging (MPI) is capable of measuring velocities occurring in the coronary arteries and to compute coronary flow reserve (CFR) in a canonical phantom as a preliminary study. METHODS For basic velocity measurements, a circulation phantom was designed containing replaceable glass tubes with three varying inner diameters, matching coronary-vessel diameters. Standardised boluses of superparamagnetic-iron-oxide-nanoparticles were injected and visualised by MPI. Two image-based techniques were competitively applied to calibrate the respective glass tube and to compute the mean velocity: full-duration-at-half-maximum (FDHM) and tracer dilution (TD) method. For CFR-calculation, four necessary settings of the circulation model of a virtual vessel with an inner diameter of 4 mm were generated using differently sized glass tubes and a stenosis model. The respective velocities in stenotic glass tubes were computed without recalibration. RESULTS On velocity level, comparison showed a good agreement (rFDHM = 0.869, rTD = 0.796) between techniques, preferably better for 4 mm and 6 mm inner diameter glass tubes. On CFR level MPI-derived CFR-prediction performed considerably inferior with a relative error of 20-44%. CONCLUSIONS MPI has the ability to reliably measure coronary blood velocities at rest as well as under hyperaemia and therefore may be suitable for CFR calculation. Calibration-associated accuracy of CFR-measurements has to be improved substantially in further studies.
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Affiliation(s)
- Robert Siepmann
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Henning Nilius
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Florian Mueller
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Katrin Mueller
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Claudio Luisi
- Applied Medical Engineering, RWTH Aachen University, Aachen, Germany
| | | | - Marcel Straub
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
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Nadig V, Schug D, Weissler B, Schulz V. Evaluation of the PETsys TOFPET2 ASIC in multi-channel coincidence experiments. EJNMMI Phys 2021; 8:30. [PMID: 33761038 PMCID: PMC7991069 DOI: 10.1186/s40658-021-00370-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 02/23/2021] [Indexed: 04/05/2023] Open
Abstract
BACKGROUND Aiming to measure the difference in arrival times of two coincident γ-photons with an accuracy in the order of 200ps, time-of-flight positron emission tomography systems commonly employ silicon photomultipliers (SiPMs) and high-resolution digitization electronics, application specific integrated circuits (ASICs). This work evaluates the performance of the TOFPET2 ASIC, released by PETsys Electronics S.A. in 2017, dependent on its configuration parameters in multi-channel coincidence measurements. METHODS SiPM arrays fabricated by different vendors (KETEK, SensL, Hamamatsu, Broadcom) were tested in combination with the ASIC. Scintillator arrays featuring different reflector designs and different configurations of the TOFPET2 ASIC software parameters were evaluated. The benchtop setup used is provided with the TOFPET2 ASIC evaluation kit by PETsys Electronics S.A. RESULTS Compared to existing studies featuring the TOFPET2 ASIC, multi-channel performance results dependent on a larger set of ASIC configuration parameters were obtained that have not been reported to this extend so far. The ASIC shows promising CRTs down to 219.9 ps in combination with two Hamamatsu S14161-3050-HS-08 SiPM arrays (128 channels read out, energy resolution 13.08%) and 216.1 ps in combination with two Broadcom AFBR-S4N44P643S SiPM arrays (32 channels read out, energy resolution 9.46%). The length of the trigger delay of the dark count suppression scheme has an impact on the ASIC performance and can be configured to further improve the coincidence resolution time. The integrator gain configuration has been investigated and allows an absolute improvement of the energy resolution by up to 1% at the cost of the linearity of the energy spectrum. CONCLUSION Measuring up to the time-of-flight performance of state-of-the-art positron emission tomography (ToF-PET) systems while providing a uniform and stable readout for multiple channels at the same time, the TOFPET2 ASIC is treated as promising candidate for the integration in future ToF-PET systems.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 17, Aachen, 52074 Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 17, Aachen, 52074 Germany
- Hyperion Hybrid Imaging Systems GmbH, Pauwelsstrasse 19, Aachen, 52074 Germany
| | - Bjoern Weissler
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 17, Aachen, 52074 Germany
- Hyperion Hybrid Imaging Systems GmbH, Pauwelsstrasse 19, Aachen, 52074 Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 17, Aachen, 52074 Germany
- Hyperion Hybrid Imaging Systems GmbH, Pauwelsstrasse 19, Aachen, 52074 Germany
- III. Physikalisches Institut B, RWTH Aachen University, Otto-Blumenthal-Straße, Aachen, 52074 Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Forckenbeckstrasse 55, Aachen, 52074 Germany
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Branderhorst W, Steensma BR, Beijst C, Huijing ER, Alborahal C, Versteeg E, Weissler B, Schug D, Gebhardt P, Gross-Weege N, Mueller F, Krueger K, Dey T, Radermacher H, Lips O, Lagendijk J, Schulz V, de Jong HWAM, Klomp DWJ. Evaluation of the radiofrequency performance of a wide-bore 1.5 T positron emission tomography/magnetic resonance imaging body coil for radiotherapy planning. Phys Imaging Radiat Oncol 2020; 17:13-19. [PMID: 33898772 PMCID: PMC8057958 DOI: 10.1016/j.phro.2020.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 11/17/2020] [Accepted: 12/09/2020] [Indexed: 11/13/2022]
Abstract
Background and purpose The restricted bore diameter of current simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) systems can be an impediment to achieving similar patient positioning during PET/MRI planning and radiotherapy. Our goal was to evaluate the B1 transmit (B1+) uniformity, B1+ efficiency, and specific absorption rate (SAR) of a novel radiofrequency (RF) body coil design, in which RF shielded PET detectors were integrated with the specific aim of enabling a wide-bore PET/MRI system. Materials and methods We designed and constructed a wide-bore PET/MRI RF body coil to be integrated with a clinical MRI system. To increase its inner bore diameter, the PET detectors were positioned between the conductors and the RF shield of the RF body coil. Simulations and experiments with phantoms and human volunteers were performed to compare the B1+ uniformity, B1+ efficiency, and SAR between our design and the clinical body coil. Results In the simulations, our design achieved nearly the same B1+ field uniformity as the clinical body coil and an almost identical SAR distribution. The uniformity findings were confirmed by the physical experiments. The B1+ efficiency was 38% lower compared to the clinical body coil. Conclusions To achieve wide-bore PET/MRI, it is possible to integrate shielding for PET detectors between the body coil conductors and the RF shield without compromising MRI performance. Reduced B1+ efficiency may be compensated by adding a second RF amplifier. This finding may facilitate the application of simultaneous whole-body PET/MRI in radiotherapy planning.
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Affiliation(s)
- Woutjan Branderhorst
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bart R Steensma
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Casper Beijst
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Erik R Huijing
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Cezar Alborahal
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Edwin Versteeg
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bjoern Weissler
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Pierre Gebhardt
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Nicolas Gross-Weege
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Florian Mueller
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Karl Krueger
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Thomas Dey
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Harald Radermacher
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | | | - Jan Lagendijk
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Hugo W A M de Jong
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dennis W J Klomp
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
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Franke J, Baxan N, Lehr H, Heinen U, Reinartz S, Schnorr J, Heidenreich M, Kiessling F, Schulz V. Hybrid MPI-MRI System for Dual-Modal In Situ Cardiovascular Assessments of Real-Time 3D Blood Flow Quantification-A Pre-Clinical In Vivo Feasibility Investigation. IEEE Trans Med Imaging 2020; 39:4335-4345. [PMID: 32804645 DOI: 10.1109/tmi.2020.3017160] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Non-invasive quantification of functional parameters of the cardiovascular system, in particular the heart, remains very challenging with current imaging techniques. This aspect is mainly due to the fact, that the spatio-temporal resolution of current imaging methods, such as Magnetic Resonance Imaging (MRI) or Positron Emission Tomography (PET), does not offer the desired data repetition rates in the context of real-time data acquisition and thus, can cause artifacts and misinterpretations in accelerated data acquisition approaches. We present a fast non-invasive and quantitative dual-modal in situ cardiovascular assessment using a hybrid imaging system which combines the new imaging modality Magnetic Particle Imaging (MPI) and MRI. This pre-clinical hybrid imaging system provides either a 0.5 T homogeneous B0 field for MRI or a 2.2 T/m gradient field featuring a Field-Free-Point for MPI. A comprehensive coil system allows in both imaging modes for spatial encoding, signal excitation and reception. In this work, 3-dimensional anatomical information acquired with MRI is combined with in situ sequentially acquired time-resolved 3D (i.e. 3D + t) MPI bolus tracking of superparamagnetic iron oxide nanoparticles. MPI data were acquired during a 21 [Formula: see text] (40 μ mol(Fe)/kgBW) bolus tail vein injection under free-breathing with an ungated and non-triggered MPI scan with a repetition rate of 46 volumes per seconds. We successfully determined quantitative hemodynamics as 3D + t velocity vector estimations of a beating rat's heart by analyzing 3 seconds of 3D + t MPI image data. The used hybrid system allows for MR-based MPI Field-of-View planning and cardiac cross-sectional anatomy analysis, precise co-registration of dual-modal datasets, as well as for MPI-based hemodynamic functional analysis using an optical flow technique. We present the first in-vivo results of a new methodology, allowing for fast, non-invasive, quantitative and in situ hybrid cardiovascular assessment, showing its potential for future clinical applications.
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Han T, Nebelung S, Haarburger C, Horst N, Reinartz S, Merhof D, Kiessling F, Schulz V, Truhn D. Breaking medical data sharing boundaries by using synthesized radiographs. Sci Adv 2020; 6:eabb7973. [PMID: 33268370 PMCID: PMC7821879 DOI: 10.1126/sciadv.abb7973] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 10/14/2020] [Indexed: 05/23/2023]
Abstract
Computer vision (CV) has the potential to change medicine fundamentally. Expert knowledge provided by CV can enhance diagnosis. Unfortunately, existing algorithms often remain below expectations, as databases used for training are usually too small, incomplete, and heterogeneous in quality. Moreover, data protection is a serious obstacle to the exchange of data. To overcome this limitation, we propose to use generative models (GMs) to produce high-resolution synthetic radiographs that do not contain any personal identification information. Blinded analyses by CV and radiology experts confirmed the high similarity of synthesized and real radiographs. The combination of pooled GM improves the performance of CV algorithms trained on smaller datasets, and the integration of synthesized data into patient data repositories can compensate for underrepresented disease entities. By integrating federated learning strategies, even hospitals with few datasets can contribute to and benefit from GM training.
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Affiliation(s)
- Tianyu Han
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Sven Nebelung
- Department of Diagnostic and Interventional Radiology, University Hospital Düsseldorf, Düsseldorf, Germany
| | | | - Nicolas Horst
- Institute of Imaging and Computer Vision, RWTH Aachen University, Aachen, Germany
| | - Sebastian Reinartz
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
| | - Dorit Merhof
- Institute of Imaging and Computer Vision, RWTH Aachen University, Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
- Comprehensive Diagnostic Center Aachen (CDCA), University Hospital RWTH Aachen, Aachen, Germany
| | - Fabian Kiessling
- Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
- Comprehensive Diagnostic Center Aachen (CDCA), University Hospital RWTH Aachen, Aachen, Germany
- Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
- Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
- Comprehensive Diagnostic Center Aachen (CDCA), University Hospital RWTH Aachen, Aachen, Germany
| | - Daniel Truhn
- Aristra GmbH, Berlin, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Aachen, Aachen, Germany
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Nolte T, Scholten H, Gross-Weege N, Amthor T, Koken P, Doneva M, Schulz V. Confounding factors in breast magnetic resonance fingerprinting: B 1 + , slice profile, and diffusion effects. Magn Reson Med 2020; 85:1865-1880. [PMID: 33118649 DOI: 10.1002/mrm.28545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 09/03/2020] [Accepted: 09/14/2020] [Indexed: 11/09/2022]
Abstract
PURPOSE Magnetic resonance fingerprinting (MRF) offers rapid quantitative imaging but may be subject to confounding effects (CE) if these are not included in the model-based reconstruction. This study characterizes the influence of in-plane B 1 + , slice profile and diffusion effects on T1 and T2 estimation in the female breast at 1.5T. METHODS Simulations were used to predict the influence of each CE on the accuracy of MRF and to investigate the influence of electronic noise and spiral aliasing artefacts. The experimentally observed bias in regions of fibroglandular tissue (FGT) and fatty tissue (FT) was analyzed for undersampled spiral breast MRF data of 6 healthy volunteers by performing MRF reconstruction with and without a CE. RESULTS Theoretic analysis predicts T1 under-/T2 overestimation if the nominal flip angles are underestimated and inversely, T1 under-/T2 overestimation if omitting slice profile correction, and T1 under-/T2 underestimation if omitting diffusion in the signal model. Averaged over repeated signal simulations, including spiral aliasing artefacts affected precision more than accuracy. Strong in-plane B 1 + effects occurred in vivo, causing T2 left-right inhomogeneity between both breasts. Their correction decreased the T2 difference from 29 to 5 ms in FGT and from 29 to 9 ms in FT. Slice profile correction affected FGT T2 most strongly, resulting in -22% smaller values. For the employed spoiler gradient strengths, diffusion did not affect the parameter maps, corresponding well with theoretic predictions. CONCLUSION Understanding CEs and their relative significance for an MRF sequence is important when defining an MRF signal model for accurate parameter mapping.
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Affiliation(s)
- Teresa Nolte
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Hannah Scholten
- Department of Diagnostic and Interventional Radiology, University of Würzburg, Würzburg, Germany
| | - Nicolas Gross-Weege
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Thomas Amthor
- Tomographic Imaging Systems, Philips Research Europe, Hamburg, Germany
| | - Peter Koken
- Tomographic Imaging Systems, Philips Research Europe, Hamburg, Germany
| | - Mariya Doneva
- Tomographic Imaging Systems, Philips Research Europe, Hamburg, Germany
| | - Volkmar Schulz
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.,Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany.,Physics Institute III B, RWTH Aachen University, Aachen, Germany
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Hetzel R, Mueller F, Grahe J, Honne A, Schug D, Schulz V. Characterization and Simulation of an Adaptable Fan-Beam Collimator for Fast Calibration of Radiation Detectors for PET. IEEE Trans Radiat Plasma Med Sci 2020. [DOI: 10.1109/trpms.2020.2990651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Theek B, Magnuska Z, Gremse F, Hahn H, Schulz V, Kiessling F. Automation of data analysis in molecular cancer imaging and its potential impact on future clinical practice. Methods 2020; 188:30-36. [PMID: 32615232 DOI: 10.1016/j.ymeth.2020.06.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/23/2020] [Indexed: 12/11/2022] Open
Abstract
Digitalization, especially the use of machine learning and computational intelligence, is considered to dramatically shape medical procedures in the near future. In the field of cancer diagnostics, radiomics, the extraction of multiple quantitative image features and their clustered analysis, is gaining increasing attention to obtain more detailed, reproducible, and meaningful information about the disease entity, its prognosis and the ideal therapeutic option. In this context, automation of diagnostic procedures can improve the entire pipeline, which comprises patient registration, planning and performing an imaging examination at the scanner, image reconstruction, image analysis, and feeding the diagnostic information from various sources into decision support systems. With a focus on cancer diagnostics, this review article reports and discusses how computer-assistance can be integrated into diagnostic procedures and which benefits and challenges arise from it. Besides a strong view on classical imaging modalities like x-ray, CT, MRI, ultrasound, PET, SPECT and hybrid imaging devices thereof, it is outlined how imaging data can be combined with data deriving from patient anamnesis, clinical chemistry, pathology, and different omics. In this context, the article also discusses IT infrastructures that are required to realize this integration in the clinical routine. Although there are still many challenges to comprehensively implement automated and integrated data analysis in molecular cancer imaging, the authors conclude that we are entering a new era of medical diagnostics and precision medicine.
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Affiliation(s)
- Benjamin Theek
- Institute for Experimental Molecular Imaging, University Clinic and Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Forckenbeckstrasse 55, 52074 Aachen, Germany; Fraunhofer Institute for Digital Medicine MEVIS, Am Fallturm 1, 28359 Bremen, Germany
| | - Zuzanna Magnuska
- Institute for Experimental Molecular Imaging, University Clinic and Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Forckenbeckstrasse 55, 52074 Aachen, Germany
| | - Felix Gremse
- Institute for Experimental Molecular Imaging, University Clinic and Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Forckenbeckstrasse 55, 52074 Aachen, Germany; Institute of Medical Informatics, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Horst Hahn
- Fraunhofer Institute for Digital Medicine MEVIS, Am Fallturm 1, 28359 Bremen, Germany
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, University Clinic and Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Forckenbeckstrasse 55, 52074 Aachen, Germany; Fraunhofer Institute for Digital Medicine MEVIS, Am Fallturm 1, 28359 Bremen, Germany; Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstrasse 55, 52074 Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, University Clinic and Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Forckenbeckstrasse 55, 52074 Aachen, Germany; Fraunhofer Institute for Digital Medicine MEVIS, Am Fallturm 1, 28359 Bremen, Germany.
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Abstract
Imaging modalities have developed rapidly in recent decades. In addition to improved resolution as well as whole-body and faster image acquisition, the possibilities of functional and molecular examination of tissue pathophysiology have had a decisive influence on imaging diagnostics and provided ground-breaking knowledge. Many promising approaches are currently being pursued to increase the application area of devices and contrast media and to improve their sensitivity and quantitative informative value. These are complemented by new methods of data processing, multiparametric data analysis, and integrated diagnostics. The aim of this article is to provide an overview of technological innovations that will enrich clinical imaging in the future, and to highlight the resultant diagnostic options. These relate to the established imaging methods such as CT, MRI, ultrasound, PET, and SPECT but also to new methods such as magnetic particle imaging (MPI), optical imaging, and photoacoustics. In addition, approaches to radiomic image evaluation are explained and the chances and difficulties for their broad clinical introduction are discussed. The potential of imaging to describe pathophysiological relationships in ever increasing detail, both at whole-body and tissue level, can in future be used to better understand the mechanistic effect of drugs, to preselect patients to therapies, and to improve monitoring of therapy success. Consequently, the use of interdisciplinary integrated diagnostics will greatly change and enrich the profession of radiologists.
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Affiliation(s)
- B Theek
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen International University, Forckenbeckstraße 55, 52074, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
| | - T Nolte
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen International University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - D Pantke
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen International University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - F Schrank
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen International University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - F Gremse
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen International University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - V Schulz
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen International University, Forckenbeckstraße 55, 52074, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany.,Comprehensive Diagnostic Center Aachen (CDCA), University Hospital RWTH Aachen, Aachen, Germany
| | - F Kiessling
- Institute for Experimental Molecular Imaging, Medical Faculty, RWTH Aachen International University, Forckenbeckstraße 55, 52074, Aachen, Germany. .,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany. .,Comprehensive Diagnostic Center Aachen (CDCA), University Hospital RWTH Aachen, Aachen, Germany.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Bjoern Weissler
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Harald Radermacher
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
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Hallen P, Schug D, Schulz V. Comments on the NEMA NU 4-2008 Standard on Performance Measurement of Small Animal Positron Emission Tomographs. EJNMMI Phys 2020; 7:12. [PMID: 32095909 PMCID: PMC7040118 DOI: 10.1186/s40658-020-0279-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 02/04/2020] [Indexed: 11/12/2022] Open
Abstract
The National Electrical Manufacturers Association’s (NEMA) NU 4-2008 standard specifies methodology for evaluating the performance of small-animal PET scanners. The standard’s goal is to enable comparison of different PET scanners over a wide range of technologies and geometries used. In this work, we discuss if the NEMA standard meets these goals and we point out potential flaws and improvements to the standard.For the evaluation of spatial resolution, the NEMA standard mandates the use of filtered backprojection reconstruction. This reconstruction method can introduce star-like artifacts for detectors with an anisotropic spatial resolution, usually caused by parallax error. These artifacts can then cause a strong dependence of the resulting spatial resolution on the size of the projection window in image space, whose size is not fully specified in the NEMA standard. If the PET ring has detectors which are perpendicular to a Cartesian axis, then the resolution along this axis will typically improve with larger projection windows.We show that the standard’s equations for the estimation of the random rate for PET systems with intrinsic radioactivity are circular and not satisfiable. However, a modified version can still be used to determine an approximation of the random rates under the assumption of negligible random rates for small activities and a constant scatter fraction. We compare the resulting estimated random rates to random rates obtained using a delayed coincidence window and two methods based on the singles rates. While these methods give similar estimates, the estimation method based on the NEMA equations overestimates the random rates.In the NEMA standard’s protocol for the evaluation of the sensitivity, the standard specifies to axially step a point source through the scanner and to take a different scan for each source position. Later, in the data analysis section, the standard does not specify clearly how the different scans have to be incorporated into the analysis, which can lead to unclear interpretations of publicized results.The standard’s definition of the recovery coefficients in the image quality phantom includes the maximum activity in a region of interest, which causes a positive correlation of noise and recovery coefficients. This leads to an unintended trade-off between desired uniformity, which is negatively correlated with variance (i.e., noise), and recovery.With this work, we want to start a discussion on possible improvements in a next version of the NEMA NU-4 standard.
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Affiliation(s)
- Patrick Hallen
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelstraße 19, Aachen, 52074, Germany.
| | - David Schug
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelstraße 19, Aachen, 52074, Germany.,Hyperion Hybrid Imaging Systems GmbH, Pauwelstraße 19, Aachen, 52074, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelstraße 19, Aachen, 52074, Germany.,Hyperion Hybrid Imaging Systems GmbH, Pauwelstraße 19, Aachen, 52074, Germany.,III. Physikalisches Institut B, RWTH Aachen University, Otto-Blumenthal-Straße, Aachen, 52074, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Forckenbeckstrasse 55, Aachen, 52074, Germany
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Dadfar SM, Camozzi D, Darguzyte M, Roemhild K, Varvarà P, Metselaar J, Banala S, Straub M, Güvener N, Engelmann U, Slabu I, Buhl M, van Leusen J, Kögerler P, Hermanns-Sachweh B, Schulz V, Kiessling F, Lammers T. Size-isolation of superparamagnetic iron oxide nanoparticles improves MRI, MPI and hyperthermia performance. J Nanobiotechnology 2020; 18:22. [PMID: 31992302 PMCID: PMC6986086 DOI: 10.1186/s12951-020-0580-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 01/11/2020] [Indexed: 11/10/2022] Open
Abstract
Superparamagnetic iron oxide nanoparticles (SPION) are extensively used for magnetic resonance imaging (MRI) and magnetic particle imaging (MPI), as well as for magnetic fluid hyperthermia (MFH). We here describe a sequential centrifugation protocol to obtain SPION with well-defined sizes from a polydisperse SPION starting formulation, synthesized using the routinely employed co-precipitation technique. Transmission electron microscopy, dynamic light scattering and nanoparticle tracking analyses show that the SPION fractions obtained upon size-isolation are well-defined and almost monodisperse. MRI, MPI and MFH analyses demonstrate improved imaging and hyperthermia performance for size-isolated SPION as compared to the polydisperse starting mixture, as well as to commercial and clinically used iron oxide nanoparticle formulations, such as Resovist® and Sinerem®. The size-isolation protocol presented here may help to identify SPION with optimal properties for diagnostic, therapeutic and theranostic applications.
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Affiliation(s)
- Seyed Mohammadali Dadfar
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Denise Camozzi
- Department of Biomolecular Sciences, University of Urbino 'Carlo Bo', Via Aurelio Saffi 2, 61029, Urbino, Italy
| | - Milita Darguzyte
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Karolin Roemhild
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Paola Varvarà
- Department of Scienze E Tecnologie Biologiche, Chimiche E Farmaceutiche (STEBICEF), University of Palermo, Palermo, Italy
| | - Josbert Metselaar
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Srinivas Banala
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Marcel Straub
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Nihan Güvener
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Ulrich Engelmann
- Institute of Applied Medical Engineering, Helmholtz Institute, Faculty of Medicine, RWTH Aachen University, Pauwelsstrasse 20, 52074, Aachen, Germany
| | - Ioana Slabu
- Institute of Applied Medical Engineering, Helmholtz Institute, Faculty of Medicine, RWTH Aachen University, Pauwelsstrasse 20, 52074, Aachen, Germany
| | - Miriam Buhl
- Electron Microscopy, Institute of Pathology, Faculty of Medicine, RWTH Aachen University, Pauwelstrasse 30, 52074, Aachen, Germany
| | - Jan van Leusen
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Paul Kögerler
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Benita Hermanns-Sachweh
- Electron Microscopy, Institute of Pathology, Faculty of Medicine, RWTH Aachen University, Pauwelstrasse 30, 52074, Aachen, Germany
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Twan Lammers
- Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany. .,Department of Pharmaceutics, Utrecht University, Utrecht, The Netherlands. .,Department of Targeted Therapeutics, University of Twente, Enschede, The Netherlands.
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Hack CC, Häberle L, Brucker SY, Janni W, Volz B, Loehberg CR, Hartkopf AD, Walter CB, Baake G, Fridman A, Malter W, Wuerstlein R, Harbeck N, Hoffmann O, Kuemmel S, Martin B, Thomssen C, Graf H, Wolf C, Lux MP, Bayer CM, Rauh C, Almstedt K, Gass P, Heindl F, Brodkorb T, Willer L, Lindner C, Kolberg HC, Krabisch P, Weigel M, Steinfeld-Birg D, Kohls A, Brucker C, Schulz V, Fischer G, Pelzer V, Rack B, Beckmann MW, Fehm T, Rody A, Maass N, Hein A, Fasching PA, Nabieva N. Complementary and alternative medicine and musculoskeletal pain in the first year of adjuvant aromatase inhibitor treatment in early breast cancer patients. Breast 2020; 50:11-18. [PMID: 31958661 PMCID: PMC7377331 DOI: 10.1016/j.breast.2019.12.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 12/30/2019] [Accepted: 12/31/2019] [Indexed: 12/25/2022] Open
Abstract
Background Patients with breast cancer (BC) show strong interest in complementary and alternative medicine (CAM), particularly for adverse effects of adjuvant endocrine treatment — e.g., with letrozole. Letrozole often induces myalgia/limb pain and arthralgia, with potential noncompliance and treatment termination. This analysis investigated whether CAM before aromatase inhibitor (AI) therapy is associated with pain development and the intensity of AI-induced musculoskeletal syndrome (AIMSS) during the first year of treatment. Patients and methods The multicenter phase IV PreFace study evaluated letrozole therapy in postmenopausal, hormone receptor–positive patients with early BC. Patients were asked about CAM use before, 6 months after, and 12 months after treatment started. They recorded pain every month for 1 year in a diary including questions about pain and numeric pain rating scales. Data were analyzed for patients who provided pain information for all time points. Results Of 1396 patients included, 901 (64.5%) had used CAM before AI treatment. Throughout the observation period, patients with CAM before AI treatment had higher pain values, for both myalgia/limb pain and arthralgia, than non-users. Pain increased significantly in both groups over time, with the largest increase during the first 6 months. No significant difference of pain increase was noted regarding CAM use. Conclusions CAM use does not prevent or improve the development of AIMSS. Pain intensity was generally greater in the CAM group. Therefore, because of the risk of non-compliance and treatment discontinuation due to the development of higher pain levels, special attention must be paid to patient education and aftercare in these patients. Pain levels of myalgia/limb pain and arthralgia increase under letrozole intake. Within one year pain levels increase in both, CAM users as well as non-CAM users. In CAM users pain levels were higher at all time points than in non-CAM users. The greatest increase of pain levels was noted in the first six treatment months. CAM does not prevent or improve the development of myalgia/limb pain and arthralgia.
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Affiliation(s)
- C C Hack
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - L Häberle
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany; Biostatistics Unit, Department of Gynecology, Erlangen University Hospital, Erlangen, Germany
| | - S Y Brucker
- Department of Gynecology, University of Tübingen, Tübingen, Germany
| | - W Janni
- Department of Gynecology, Ulm University Hospital, Ulm, Germany
| | - B Volz
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - C R Loehberg
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany; St. Theresien Hospital, Nuremberg, Germany
| | - A D Hartkopf
- Department of Gynecology, University of Tübingen, Tübingen, Germany
| | - C-B Walter
- Department of Gynecology, University of Tübingen, Tübingen, Germany
| | - G Baake
- Oncological Medical Practice Pinneberg, Pinneberg, Germany
| | - A Fridman
- Breast Center, Department of Obstetrics and Gynecology, University of Cologne Hospital, Cologne, Germany; Evangelisches Krankenhaus Kalk, Cologne, Germany
| | - W Malter
- Breast Center, Department of Obstetrics and Gynecology, University of Cologne Hospital, Cologne, Germany
| | - R Wuerstlein
- Breast Center, Department of Obstetrics and Gynecology, University of Cologne Hospital, Cologne, Germany; Breast Center, Department of Gynecology and Obstetrics and CCC Munich, University of Munich (LMU), Munich, Germany
| | - N Harbeck
- Breast Center, Department of Obstetrics and Gynecology, University of Cologne Hospital, Cologne, Germany; Breast Center, Department of Gynecology and Obstetrics and CCC Munich, University of Munich (LMU), Munich, Germany
| | - O Hoffmann
- Department of Gynecology, Essen University Hospital, Essen, Germany
| | - S Kuemmel
- Breast Unit, Essen Mitte Clinics, Evang. Huyssens-Stiftung/Knappschaft GmbH, Essen, Germany
| | - B Martin
- Tuttlingen Clinic, Tuttlingen, Germany
| | - C Thomssen
- Department of Gynecology, Martin Luther University of Halle-Wittenberg, Halle (Saale), Germany
| | - H Graf
- Helios Clinics Meiningen, Meiningen, Germany
| | - C Wolf
- Ulm Medical Center, Ulm, Germany
| | - M P Lux
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - C M Bayer
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - C Rauh
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - K Almstedt
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany; Department of Gynecology, Mainz University Hospital, Mainz, Germany
| | - P Gass
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - F Heindl
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - T Brodkorb
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - L Willer
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - C Lindner
- Agaplesion Diakonie Clinic Hamburg, Hamburg, Germany
| | - H-C Kolberg
- Department of Gynecology and Obstetrics, Marienhospital Bottrop, Bottrop, Germany
| | - P Krabisch
- Department of Gynecology, Klinikum Chemnitz gGmbH, Chemnitz, Germany
| | - M Weigel
- Department of Gynecology, Leopoldina Hospital Schweinfurt, Schweinfurt, Germany
| | - D Steinfeld-Birg
- Gynecologic Onocologic Practice Steinfeld-Birg, Augsburg, Germany
| | - A Kohls
- Protestant County Hospital of Ludwigsfelde-Teltow, Ludwigsfelde-Teltow, Germany
| | - C Brucker
- Department of Gynecology and Obstetrics, Nuremberg General Hospital, Paracelsus Medical University, Nuremberg, Germany
| | - V Schulz
- Gynecologic Practice Abts+partner, Kiel, Germany
| | - G Fischer
- Mittweida Hospital gGmbH, Mittweida, Germany
| | - V Pelzer
- Department of Gynecology, GFO Clinics Bonn, Bonn, Germany
| | - B Rack
- Department of Gynecology, Ulm University Hospital, Ulm, Germany
| | - M W Beckmann
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - T Fehm
- Department of Gynecology, University of Tübingen, Tübingen, Germany; Department of Gynecology, Heinrich Heine University of Dusseldorf, Dusseldorf, Germany
| | - A Rody
- Department of Gynecology, Campus Lübeck, Schleswig-Holstein University Hospital, Schleswig-Holstein, Germany
| | - N Maass
- Department of Gynecology, Campus Kiel, Schleswig-Holstein University Hospital, Schleswig-Holstein, Germany
| | - A Hein
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - P A Fasching
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany.
| | - N Nabieva
- Department of Gynecology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
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Abstract
SPECT and PET are nuclear tomographic imaging modalities that visualize functional information based on the accumulation of radioactive tracer molecules. However, SPECT and PET lack anatomical information, which has motivated their combination with an anatomical imaging modality such as CT or MRI. This chapter begins with an overview over the fundamental physics of SPECT and PET followed by a presentation of the respective detector technologies, including detection requirements, principles and different detector concepts. The reader is subsequently provided with an introduction into hybrid imaging concepts, before a dedicated section presents the challenges that arise when hybridizing SPECT or PET with MRI, namely, mutual distortions of the different electromagnetic fields in MRI on the nuclear imaging system and vice versa. The chapter closes with an overview about current hybrid imaging systems of both clinical and preclinical kind. Finally, future developments in hybrid SPECT and PET technology are discussed.
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Affiliation(s)
- Teresa Nolte
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Nicolas Gross-Weege
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.
- Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany.
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Berker Y, Schulz V, Karp JS. Algorithms for joint activity-attenuation estimation from positron emission tomography scatter. EJNMMI Phys 2019; 6:18. [PMID: 31659488 PMCID: PMC6816692 DOI: 10.1186/s40658-019-0254-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 09/10/2019] [Indexed: 12/31/2022] Open
Abstract
Background Attenuation correction in positron emission tomography remains challenging in the absence of measured transmission data. Scattered emission data may contribute missing information, but quantitative scatter-to-attenuation (S2A) reconstruction needs to input the reconstructed activity image. Here, we study S2A reconstruction as a building block for joint estimation of activity and attenuation. Methods We study two S2A reconstruction algorithms, maximum-likelihood expectation maximization (MLEM) with one-step-late attenuation (MLEM-OSL) and a maximum-likelihood gradient ascent (MLGA). We study theoretical properties of these algorithms with a focus on convergence and convergence speed and compare convergence speeds and the impact of object size in simulations using different spatial scale factors. Then, we propose joint estimation of activity and attenuation from scattered and nonscattered (true) emission data, combining MLEM-OSL or MLGA with scatter-MLEM as well as trues-MLEM and the maximum-likelihood transmission (MLTR) algorithm. Results Shortcomings of MLEM-OSL inhibit convergence to the true solution with high attenuation; these shortcomings are related to the linearization of a nonlinear measurement equation and can be linked to a new numerical criterion allowing geometrical interpretations in terms of low and high attenuation. Comparisons using simulated data confirm that while MLGA converges largely independent of the attenuation scale, MLEM-OSL converges if low-attenuation data dominate, but not with high attenuation. Convergence of MLEM-OSL can be improved by isolating data satisfying the aforementioned low-attenuation criterion. In joint estimation of activity and attenuation, scattered data helps avoid local minima that nonscattered data alone cannot. Combining MLEM-OSL with trues-MLEM may be sufficient for low-attenuation objects, while MLGA, scatter-MLEM, and MLTR may additionally be needed with higher attenuation. Conclusions The performance of S2A algorithms depends on spatial scales. MLGA provides lower computational complexity and convergence in more diverse setups than MLEM-OSL. Finally, scattered data may provide additional information to joint estimation of activity and attenuation through S2A reconstruction.
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Affiliation(s)
- Yannick Berker
- Division of X-ray Imaging and Computed Tomography, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, 69120, Germany. .,Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, Aachen, 52074, Germany. .,Department of Radiology, University of Pennsylvania, 3620 Hamilton Walk, Philadelphia, 19104, PA, USA.
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, Aachen, 52074, Germany.,III. Physikalisches Institut B, RWTH Aachen University, Otto-Blumenthal-Straße, Aachen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Forckenbeckstraße 55, Aachen, 52074, Germany
| | - Joel S Karp
- Department of Radiology, University of Pennsylvania, 3620 Hamilton Walk, Philadelphia, 19104, PA, USA
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Nolte T, Gross‐Weege N, Doneva M, Koken P, Elevelt A, Truhn D, Kuhl C, Schulz V. Spiral blurring correction with water–fat separation for magnetic resonance fingerprinting in the breast. Magn Reson Med 2019; 83:1192-1207. [DOI: 10.1002/mrm.27994] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 08/23/2019] [Accepted: 08/23/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Teresa Nolte
- Physics of Molecular Imaging Systems Experimental Molecular Imaging RWTH Aachen University Aachen Germany
| | - Nicolas Gross‐Weege
- Physics of Molecular Imaging Systems Experimental Molecular Imaging RWTH Aachen University Aachen Germany
| | - Mariya Doneva
- Tomographic Imaging Systems Philips Research Europe Hamburg Germany
| | - Peter Koken
- Tomographic Imaging Systems Philips Research Europe Hamburg Germany
| | - Aaldert Elevelt
- Oncology Solutions Philips Research Europe Eindhoven The Netherlands
| | - Daniel Truhn
- Clinic for Diagnostic and Interventional Radiology University Hospital Aachen Aachen Germany
| | - Christiane Kuhl
- Clinic for Diagnostic and Interventional Radiology University Hospital Aachen Aachen Germany
| | - Volkmar Schulz
- Physics of Molecular Imaging Systems Experimental Molecular Imaging RWTH Aachen University Aachen Germany
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50
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Pantke D, Holle N, Mogarkar A, Straub M, Schulz V. Multifrequency magnetic particle imaging enabled by a combined passive and active drive field feed-through compensation approach. Med Phys 2019; 46:4077-4086. [PMID: 31183873 PMCID: PMC6851971 DOI: 10.1002/mp.13650] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 05/28/2019] [Accepted: 05/31/2019] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Magnetic particle imaging (MPI) allows fast imaging of the spatial distribution of superparamagnetic iron-oxide based nanoparticles (SPIONs). Recent research suggests that MPI furthermore promises in-vivo access to environmental parameters of SPIONs as temperature or viscosity. Various medical applications as nanomedicine, stem cell-based therapies or magnetic hyperthermia could benefit from in-vivo multiparameter estimation by MPI. One possible approach to get access to functional parameters is particle excitation at multiple frequencies. To enable the investigation of the mentioned approach, a novel MPI device capable of multifrequency excitation is needed. METHODS MPI usually employs analog band-stop filters to cancel the drive field feed-through, which is magnitudes higher than the particle signal. To enable drive field frequency flexibility over a wide bandwidth, we propose a combined passive and active drive field feed-through compensation approach. This cancellation technique further allows the direct detection of the SPIONs' signal at the fundamental excitation frequency. RESULTS A combined feed-through suppression of up to -125 dB is reported, which allows to adjust the drive field frequency from 500 Hz to 20 kHz. Initial spectroscopic measurements and images are shown that demonstrate the concept of multifrequency excitation and prove the imaging capability of the presented scanner. A mean signal-to-noise ratio (SNR) enhancement by the factor of 1.7 was shown when the first harmonic is used for measurement-based image reconstruction compared to when it is omitted. CONCLUSIONS In this paper, the first one-dimensional multifrequency magnetic particle imaging (mf-MPI) that features adjustable excitation frequencies from 500 Hz to 20 kHz is presented. The device will be used to study the principle of multiparameter estimation by employing multifrequency excitation.
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Affiliation(s)
- Dennis Pantke
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Faculty of Medicine, Aachen, Germany
| | - Nils Holle
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Faculty of Medicine, Aachen, Germany
| | - Akshay Mogarkar
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Faculty of Medicine, Aachen, Germany
| | - Marcel Straub
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Faculty of Medicine, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging, Institute for Experimental Molecular Imaging, RWTH Aachen University, Faculty of Medicine, Aachen, Germany
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