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Sanaat A, Jamalizadeh M, Khanmohammadi H, Arabi H, Zaidi H. Active-PET: a multifunctional PET scanner with dynamic gantry size featuring high-resolution and high-sensitivity imaging: a Monte Carlo simulation study. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac7fd8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 07/08/2022] [Indexed: 11/11/2022]
Abstract
Abstract
Organ-specific PET scanners have been developed to provide both high spatial resolution and sensitivity, although the deployment of several dedicated PET scanners at the same center is costly and space-consuming. Active-PET is a multifunctional PET scanner design exploiting the advantages of two different types of detector modules and mechanical arms mechanisms enabling repositioning of the detectors to allow the implementation of different geometries/configurations. Active-PET can be used for different applications, including brain, axilla, breast, prostate, whole-body, preclinical and pediatrics imaging, cell tracking, and image guidance for therapy. Monte Carlo techniques were used to simulate a PET scanner with two sets of high resolution and high sensitivity pixelated Lutetium Oxyorthoscilicate (LSO(Ce)) detector blocks (24 for each group, overall 48 detector modules for each ring), one with large pixel size (4 × 4 mm2) and crystal thickness (20 mm), and another one with small pixel size (2 × 2 mm2) and thickness (10 mm). Each row of detector modules is connected to a linear motor that can displace the detectors forward and backward along the radial axis to achieve variable gantry diameter in order to image the target subject at the optimal/desired resolution and/or sensitivity. At the center of the field-of-view, the highest sensitivity (15.98 kcps MBq−1) was achieved by the scanner with a small gantry and high-sensitivity detectors while the best spatial resolution was obtained by the scanner with a small gantry and high-resolution detectors (2.2 mm, 2.3 mm, 2.5 mm FWHM for tangential, radial, and axial, respectively). The configuration with large-bore (combination of high-resolution and high-sensitivity detectors) achieved better performance and provided higher image quality compared to the Biograph mCT as reflected by the 3D Hoffman brain phantom simulation study. We introduced the concept of a non-static PET scanner capable of switching between large and small field-of-view as well as high-resolution and high-sensitivity imaging.
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Kimm MA, Shevtsov M, Werner C, Sievert W, Zhiyuan W, Schoppe O, Menze BH, Rummeny EJ, Proksa R, Bystrova O, Martynova M, Multhoff G, Stangl S. Gold Nanoparticle Mediated Multi-Modal CT Imaging of Hsp70 Membrane-Positive Tumors. Cancers (Basel) 2020; 12:cancers12051331. [PMID: 32456049 PMCID: PMC7281090 DOI: 10.3390/cancers12051331] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/18/2020] [Accepted: 05/20/2020] [Indexed: 11/21/2022] Open
Abstract
Imaging techniques such as computed tomographies (CT) play a major role in clinical imaging and diagnosis of malignant lesions. In recent years, metal nanoparticle platforms enabled effective payload delivery for several imaging techniques. Due to the possibility of surface modification, metal nanoparticles are predestined to facilitate molecular tumor targeting. In this work, we demonstrate the feasibility of anti-plasma membrane Heat shock protein 70 (Hsp70) antibody functionalized gold nanoparticles (cmHsp70.1-AuNPs) for tumor-specific multimodal imaging. Membrane-associated Hsp70 is exclusively presented on the plasma membrane of malignant cells of multiple tumor entities but not on corresponding normal cells, predestining this target for a tumor-selective in vivo imaging. In vitro microscopic analysis revealed the presence of cmHsp70.1-AuNPs in the cytosol of tumor cell lines after internalization via the endo-lysosomal pathway. In preclinical models, the biodistribution as well as the intratumoral enrichment of AuNPs were examined 24 h after i.v. injection in tumor-bearing mice. In parallel to spectral CT analysis, histological analysis confirmed the presence of AuNPs within tumor cells. In contrast to control AuNPs, a significant enrichment of cmHsp70.1-AuNPs has been detected selectively inside tumor cells in different tumor mouse models. Furthermore, a machine-learning approach was developed to analyze AuNP accumulations in tumor tissues and organs. In summary, utilizing mHsp70 on tumor cells as a target for the guidance of cmHsp70.1-AuNPs facilitates an enrichment and uniform distribution of nanoparticles in mHsp70-expressing tumor cells that enables various microscopic imaging techniques and spectral-CT-based tumor delineation in vivo.
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Affiliation(s)
- Melanie A. Kimm
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.A.K.); (E.J.R.)
| | - Maxim Shevtsov
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
- Pavlov First Saint Petersburg State Medical University, 197022 St. Petersburg, Russia
- Institute of Cytology of the Russian Academy of Sciences (RAS), 194064 St. Petersburg, Russia; (O.B.); (M.M.)
| | - Caroline Werner
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
| | - Wolfgang Sievert
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
| | - Wu Zhiyuan
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
| | - Oliver Schoppe
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
- Institute for Advanced Studies, Department of Informatics, Technical University of Munich, 85748 Garching, Germany
| | - Bjoern H. Menze
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
- Institute for Advanced Studies, Department of Informatics, Technical University of Munich, 85748 Garching, Germany
| | - Ernst J. Rummeny
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.A.K.); (E.J.R.)
| | - Roland Proksa
- Philips GmbH Innovative Technologies, Research Laboratories, 22335 Hamburg, Germany;
| | - Olga Bystrova
- Institute of Cytology of the Russian Academy of Sciences (RAS), 194064 St. Petersburg, Russia; (O.B.); (M.M.)
| | - Marina Martynova
- Institute of Cytology of the Russian Academy of Sciences (RAS), 194064 St. Petersburg, Russia; (O.B.); (M.M.)
| | - Gabriele Multhoff
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
| | - Stefan Stangl
- Central Institute for Translational Cancer Research (TranslaTUM), Klinikum rechts der Isar der Technischen Universität München, 81675 Munich, Germany; (M.S.); (C.W.); (W.S.); (W.Z.); (O.S.); (B.H.M.); (G.M.)
- Correspondence: ; Tel.: +49-89-4140-6013; Fax: +49-89-4140-4299
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Rezaei S, Ghafarian P, Bakhshayesh-Karam M, Uribe CF, Rahmim A, Sarkar S, Ay MR. The impact of iterative reconstruction protocol, signal-to-background ratio and background activity on measurement of PET spatial resolution. Jpn J Radiol 2020; 38:231-239. [PMID: 31894449 DOI: 10.1007/s11604-019-00914-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/19/2019] [Indexed: 02/04/2023]
Abstract
OBJECTIVES The present study aims to assess the impact of acquisition time, different iterative reconstruction protocols as well as image context (including contrast levels and background activities) on the measured spatial resolution in PET images. METHODS Discovery 690 PET/CT scanner was used to quantify spatial resolutions in terms of full width half maximum (FWHM) as derived (i) directly from capillary tubes embedded in air and (ii) indirectly from 10 mm-diameter sphere of the NEMA phantom. Different signal-to-background ratios (SBRs), background activity levels and acquisition times were applied. The emission data were reconstructed using iterative reconstruction protocols. Various combinations of iterations and subsets (it × sub) were evaluated. RESULTS For capillary tubes, improved FWHM values were obtained for higher it × sub, with improved performance for PSF algorithms relative to non-PSF algorithms. For the NEMA phantom, by increasing acquisition times from 1 to 5 min, intrinsic FWHM for reconstructions with it × sub 32 (54) was improved by 15.3% (13.2%), 15.1% (13.8%), 14.5% (12.8%) and 13.7% (12.7%) for OSEM, OSEM + PSF, OSEM + TOF and OSEM + PSF + TOF, respectively. Furthermore, for all reconstruction protocols, the FWHM improved with more impact for higher it × sub. CONCLUSION Our results indicate that PET spatial resolution is greatly affected by SBR, background activity and the choice of the reconstruction protocols.
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Affiliation(s)
- Sahar Rezaei
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.,Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran
| | - Pardis Ghafarian
- Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, 19569-44413, Tehran, Iran. .,PET/CT and Cyclotron Center, Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Mehrdad Bakhshayesh-Karam
- Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, 19569-44413, Tehran, Iran.,PET/CT and Cyclotron Center, Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Carlos F Uribe
- Department of Functional Imaging, BC Cancer, Vancouver, BC, Canada
| | - Arman Rahmim
- Departments of Radiology and Physics, University of British Columbia, Vancouver, Canada.,Department of Integrative Oncology, BC Cancer Research Centre, Vancouver, Canada
| | - Saeed Sarkar
- Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Ay
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.,Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran
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Rezaei S, Ghafarian P, Jha AK, Rahmim A, Sarkar S, Ay MR. Joint compensation of motion and partial volume effects by iterative deconvolution incorporating wavelet-based denoising in oncologic PET/CT imaging. Phys Med 2019; 68:52-60. [PMID: 31743884 DOI: 10.1016/j.ejmp.2019.10.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 09/29/2019] [Accepted: 10/17/2019] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVES We aim to develop and rigorously evaluate an image-based deconvolution method to jointly compensate respiratory motion and partial volume effects (PVEs) for quantitative oncologic PET imaging, including studying the impact of various reconstruction algorithms on quantification performance. PROCEDURES An image-based deconvolution method that incorporated wavelet-based denoising within the Lucy-Richardson algorithm was implemented and assessed. The method was evaluated using phantom studies with signal-to-background ratios (SBR) of 4 and 8, and clinical data of 10 patients with 42 lung lesions ≤30 mm in diameter. In each study, PET images were reconstructed using four different algorithms: OSEM-basic, PSF, TOF, and TOFPSF. The performance was quantified using contrast recovery (CR), coefficient of variation (COV) and contrast-to-noise-ratio (CNR) metrics. Further, in each study, variabilities arising due to the four different reconstruction algorithms were assessed. RESULTS In phantom studies, incorporation of wavelet-based denoising improved COV in all cases. Processing images using proposed method yielded significantly higher CR and CNR particularly in small spheres, for all reconstruction algorithms and all SBRs (P < 0.05). In patient studies, processing images using the proposed method yielded significantly higher CR and CNR (P < 0.05). The choice of the reconstruction algorithm impacted quantification performance for changes in motion amplitude, tumor size and SBRs. CONCLUSIONS Our results provide strong evidence that the proposed joint-compensation method can yield improved PET quantification. The choice of the reconstruction algorithm led to changes in quantitative accuracy, emphasizing the need to carefully select the right combination of reconstruction-image-based compensation methods.
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Affiliation(s)
- Sahar Rezaei
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran; Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran
| | - Pardis Ghafarian
- Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran; PET/CT and Cyclotron Center, Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Abhinav K Jha
- Department of Biomedical Engineering, Washington University in St. Louis, USA; Mallinckrodt Institute of Radiology, Washington University in St. Louis, USA
| | - Arman Rahmim
- Departments of Radiology and Physics, University of British Columbia, Vancouver, Canada; Department of Integrative Oncology, BC Cancer Research Center, Vancouver, Canada
| | - Saeed Sarkar
- Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Ay
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran; Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran
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Øen SK, Aasheim LB, Eikenes L, Karlberg AM. Image quality and detectability in Siemens Biograph PET/MRI and PET/CT systems-a phantom study. EJNMMI Phys 2019; 6:16. [PMID: 31385052 PMCID: PMC6682841 DOI: 10.1186/s40658-019-0251-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 07/23/2019] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The technology of modern positron emission tomography (PET) systems continuously improving, and with it the possibility to detect smaller lesions. Since first introduced in 2010, the number of hybrid PET/magnetic resonance imaging (MRI) systems worldwide is constantly increasing. It is therefore important to assess and compare the image quality, in terms of detectability, between the PET/MRI and the well-established PET/computed tomography (CT) systems. For this purpose, a PET image quality phantom (Esser) with hot spheres, ranging from 4 to 20 mm in diameter, was prepared with fluorodeoxyglucose and sphere-to-background activity concentrations of 8:1 and 4:1, to mimic clinical conditions. The phantom was scanned on a PET/MRI and a PET/CT system for both concentrations to obtain contrast recovery coefficients (CRCs) and contrast-to-noise ratios (CNRs), for a range of reconstruction settings. The detectability of the spheres was scored by three human observers for both systems and concentrations and all reconstructions. Furthermore, the impact of acquisition time on CNR and observer detectability was investigated. RESULTS Reconstructions applying point-spread-function modeling (and time-of-flight for the PET/CT) yielded the highest CRC and CNR in general, and PET/CT demonstrated slightly higher values than PET/MRI for most sphere sizes. CNR was dependent on reconstruction settings and was maximized for 2 iterations, a pixel size of less than 2 mm and a 4 mm Gaussian filter. Acquisition times of 97 s (PET/MRI) and 150 s (PET/CT) resulted in similar total net true counts. For these acquisition times, the smallest detected spheres by the human observers in the 8:1 activity concentration was the 6-mm sphere with PET/MRI (CNR = 5.6) and the 5-mm sphere with PET/CT (CNR = 5.5). With an acquisition time of 180 s, the 5-mm sphere was also detected with PET/MRI (CNR = 5.8). The 8-mm sphere was the smallest detected sphere in the 4:1 activity concentration for both systems. CONCLUSION In this experimental study, similar detectability was found for the PET/MRI and the PET/CT, although for an increased acquisition time for the PET/MRI.
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Affiliation(s)
- Silje Kjærnes Øen
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Postbox 8905, N-7491, Trondheim, Norway.
| | - Lars Birger Aasheim
- Department of Radiology and Nuclear Medicine, St. Olavs University Hospital, Olav Kyrres gt 17, N-7006, Trondheim, Norway
| | - Live Eikenes
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Postbox 8905, N-7491, Trondheim, Norway
| | - Anna Maria Karlberg
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Postbox 8905, N-7491, Trondheim, Norway.,Department of Radiology and Nuclear Medicine, St. Olavs University Hospital, Olav Kyrres gt 17, N-7006, Trondheim, Norway
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Gregory RA, Murray I, Gear J, Aldridge MD, Levine D, Fowkes L, Waddington WA, Chua S, Flux G. Objective comparison of lesion detectability in low and medium-energy collimator iodine-123 mIBG images using a channelized Hotelling observer. Phys Med Biol 2017; 62:17-30. [PMID: 27973344 PMCID: PMC6050520 DOI: 10.1088/1361-6560/62/1/17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 10/13/2016] [Accepted: 11/09/2016] [Indexed: 11/12/2022]
Abstract
Iodine-123 mIBG imaging is widely regarded as a gold standard for diagnostic studies of neuroblastoma and adult neuroendocrine cancer although the optimal collimator for tumour imaging remains undetermined. Low-energy (LE) high-resolution (HR) collimators provide superior spatial resolution. However due to septal penetration of high-energy photons these provide poorer contrast than medium-energy (ME) general-purpose (GP) collimators. LEGP collimators improve count sensitivity. The aim of this study was to objectively compare the lesion detection efficiency of each collimator to determine the optimal collimator for diagnostic imaging. The septal penetration and sensitivity of each collimator was assessed. Planar images of the patient abdomen were simulated with static scans of a Liqui-Phil™ anthropomorphic phantom with lesion-shaped inserts, acquired with LE and ME collimators on 3 different manufacturers' gamma camera systems (Skylight (Philips), Intevo (Siemens) and Discovery (GE)). Two-hundred normal and 200 single-lesion abnormal images were created for each collimator. A channelized Hotelling observer (CHO) was developed and validated to score the images for the likelihood of an abnormality. The areas under receiver-operator characteristic (ROC) curves, Az, created from the scores were used to quantify lesion detectability. The CHO ROC curves for the LEHR collimators were inferior to the GP curves for all cameras. The LEHR collimators resulted in statistically significantly smaller Azs (p < 0.05), of on average 0.891 ± 0.004, than for the MEGP collimators, 0.933 ± 0.004. In conclusion, the reduced background provided by MEGP collimators improved 123I mIBG image lesion detectability over LEHR collimators that provided better spatial resolution.
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Affiliation(s)
- Rebecca A Gregory
- Department of Physics, the Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Downs Road, Sutton SM2 5PT, UK
| | - Iain Murray
- Department of Physics, the Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Downs Road, Sutton SM2 5PT, UK
| | - Jonathan Gear
- Department of Physics, the Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Downs Road, Sutton SM2 5PT, UK
| | - Matthew D Aldridge
- UCL Institute of Nuclear Medicine and UCL Hospitals NHS Foundation Trust, 235 Euston Road, London NW1 2BU, UK
| | - Daniel Levine
- Department of Nuclear Medicine and PET/CT, The Royal Marsden NHS Foundation Trust, Downs Road, Sutton SM2 5PT, UK
| | - Lucy Fowkes
- Department of Nuclear Medicine and PET/CT, The Royal Marsden NHS Foundation Trust, Downs Road, Sutton SM2 5PT, UK
| | - Wendy A Waddington
- UCL Institute of Nuclear Medicine and UCL Hospitals NHS Foundation Trust, 235 Euston Road, London NW1 2BU, UK
| | - Sue Chua
- Department of Nuclear Medicine and PET/CT, The Royal Marsden NHS Foundation Trust, Downs Road, Sutton SM2 5PT, UK
| | - Glenn Flux
- Department of Physics, the Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Downs Road, Sutton SM2 5PT, UK
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Wollenweber SD, Alessio AM, Kinahan PE. A phantom design for assessment of detectability in PET imaging. Med Phys 2016; 43:5051. [DOI: 10.1118/1.4960365] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Kurz C, Bauer J, Conti M, Guérin L, Eriksson L, Parodi K. Investigating the limits of PET/CT imaging at very low true count rates and high random fractions in ion-beam therapy monitoring. Med Phys 2016; 42:3979-91. [PMID: 26133598 DOI: 10.1118/1.4921995] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE External beam radiotherapy with protons and heavier ions enables a tighter conformation of the applied dose to arbitrarily shaped tumor volumes with respect to photons, but is more sensitive to uncertainties in the radiotherapeutic treatment chain. Consequently, an independent verification of the applied treatment is highly desirable. For this purpose, the irradiation-induced β(+)-emitter distribution within the patient is detected shortly after irradiation by a commercial full-ring positron emission tomography/x-ray computed tomography (PET/CT) scanner installed next to the treatment rooms at the Heidelberg Ion-Beam Therapy Center (HIT). A major challenge to this approach is posed by the small number of detected coincidences. This contribution aims at characterizing the performance of the used PET/CT device and identifying the best-performing reconstruction algorithm under the particular statistical conditions of PET-based treatment monitoring. Moreover, this study addresses the impact of radiation background from the intrinsically radioactive lutetium-oxyorthosilicate (LSO)-based detectors at low counts. METHODS The authors have acquired 30 subsequent PET scans of a cylindrical phantom emulating a patientlike activity pattern and spanning the entire patient counting regime in terms of true coincidences and random fractions (RFs). Accuracy and precision of activity quantification, image noise, and geometrical fidelity of the scanner have been investigated for various reconstruction algorithms and settings in order to identify a practical, well-suited reconstruction scheme for PET-based treatment verification. Truncated listmode data have been utilized for separating the effects of small true count numbers and high RFs on the reconstructed images. A corresponding simulation study enabled extending the results to an even wider range of counting statistics and to additionally investigate the impact of scatter coincidences. Eventually, the recommended reconstruction scheme has been applied to exemplary postirradiation patient data-sets. RESULTS Among the investigated reconstruction options, the overall best results in terms of image noise, activity quantification, and accurate geometrical recovery were achieved using the ordered subset expectation maximization reconstruction algorithm with time-of-flight (TOF) and point-spread function (PSF) information. For this algorithm, reasonably accurate (better than 5%) and precise (uncertainty of the mean activity below 10%) imaging can be provided down to 80,000 true coincidences at 96% RF. Image noise and geometrical fidelity are generally improved for fewer iterations. The main limitation for PET-based treatment monitoring has been identified in the small number of true coincidences, rather than the high intrinsic random background. Application of the optimized reconstruction scheme to patient data-sets results in a 25% - 50% reduced image noise at a comparable activity quantification accuracy and an improved geometrical performance with respect to the formerly used reconstruction scheme at HIT, adopted from nuclear medicine applications. CONCLUSIONS Under the poor statistical conditions in PET-based treatment monitoring, improved results can be achieved by considering PSF and TOF information during image reconstruction and by applying less iterations than in conventional nuclear medicine imaging. Geometrical fidelity and image noise are mainly limited by the low number of true coincidences, not the high LSO-related random background. The retrieved results might also impact other emerging PET applications at low counting statistics.
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Affiliation(s)
- Christopher Kurz
- Heidelberg Ion-Beam Therapy Center and Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg 69120, Germany
| | - Julia Bauer
- Heidelberg Ion-Beam Therapy Center and Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg 69120, Germany
| | - Maurizio Conti
- Siemens Healthcare Molecular Imaging, Knoxville, Tennessee 37932
| | - Laura Guérin
- Siemens Healthcare Molecular Imaging, Knoxville, Tennessee 37932
| | - Lars Eriksson
- Siemens Healthcare Molecular Imaging, Knoxville, Tennessee 37932
| | - Katia Parodi
- Heidelberg Ion-Beam Therapy Center and Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg 69120, Germany and Department of Experimental Physics - Medical Physics, Ludwig-Maximilians-University, Munich 85748, Germany
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PET guidance in prostate cancer radiotherapy: Quantitative imaging to predict response and guide treatment. Phys Med 2016; 32:452-8. [DOI: 10.1016/j.ejmp.2016.02.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 01/23/2016] [Accepted: 02/01/2016] [Indexed: 12/27/2022] Open
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Gong K, Cherry SR, Qi J. On the assessment of spatial resolution of PET systems with iterative image reconstruction. Phys Med Biol 2016; 61:N193-202. [PMID: 26864088 DOI: 10.1088/0031-9155/61/5/n193] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Spatial resolution is an important metric for performance characterization in PET systems. Measuring spatial resolution is straightforward with a linear reconstruction algorithm, such as filtered backprojection, and can be performed by reconstructing a point source scan and calculating the full-width-at-half-maximum (FWHM) along the principal directions. With the widespread adoption of iterative reconstruction methods, it is desirable to quantify the spatial resolution using an iterative reconstruction algorithm. However, the task can be difficult because the reconstruction algorithms are nonlinear and the non-negativity constraint can artificially enhance the apparent spatial resolution if a point source image is reconstructed without any background. Thus, it was recommended that a background should be added to the point source data before reconstruction for resolution measurement. However, there has been no detailed study on the effect of the point source contrast on the measured spatial resolution. Here we use point source scans from a preclinical PET scanner to investigate the relationship between measured spatial resolution and the point source contrast. We also evaluate whether the reconstruction of an isolated point source is predictive of the ability of the system to resolve two adjacent point sources. Our results indicate that when the point source contrast is below a certain threshold, the measured FWHM remains stable. Once the contrast is above the threshold, the measured FWHM monotonically decreases with increasing point source contrast. In addition, the measured FWHM also monotonically decreases with iteration number for maximum likelihood estimate. Therefore, when measuring system resolution with an iterative reconstruction algorithm, we recommend using a low-contrast point source and a fixed number of iterations.
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Affiliation(s)
- Kuang Gong
- Department of Biomedical Engineering, University of California, Davis, CA, USA
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Dankbaar JW, Snijders TJ, Robe PA, Seute T, Eppinga W, Hendrikse J, De Keizer B. The use of (18)F-FDG PET to differentiate progressive disease from treatment induced necrosis in high grade glioma. J Neurooncol 2015; 125:167-75. [PMID: 26384811 PMCID: PMC4592487 DOI: 10.1007/s11060-015-1883-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 08/08/2015] [Indexed: 11/25/2022]
Abstract
In the follow-up of patients treated for high grade glioma, differentiation between progressive disease (PD) and treatment-induced necrosis (TIN) is challenging. The purpose of this study is to evaluate the diagnostic accuracy of FDG PET for the differentiation between TIN and PD after high grade glioma treatment. We retrospectively identified patients between January 2011 and July 2013 that met the following criteria: age >18; glioma grade 3 or 4; treatment with radiotherapy or chemoradiotherapy; new or progressive enhancement on post treatment MRI; FDG PET within 4 weeks of MRI. Absolute and relative (to contralateral white matter) values of SUVmax and SUVpeak were determined in new enhancing lesions on MRI. The outcome of PD or TIN was determined by neurosurgical biopsy/resection, follow-up MRI, or clinical deterioration. The association between FDG PET and outcome was analyzed with univariate logistic regression and ROC analysis for: all lesions, lesions >10, >15, and >20 mm. We included 30 patients (5 grade 3 and 25 grade 4), with 39 enhancing lesions on MRI. Twenty-nine lesions represented PD and 10 TIN. Absolute and relative values of SUVmax and SUVpeak showed no significant differences between PD and TIN. ROC analysis showed highest AUCs for relative SUVpeak in all lesion sizes. Relative SUVpeak for lesions >20 mm showed reasonable discriminative properties [AUC 0.69 (0.41–0.96)]. FDG PET has reasonable discriminative properties for differentiation of PD from TIN in high grade gliomas larger than 20 mm. Overall diagnostic performance is insufficient to guide clinical decision-making.
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Affiliation(s)
- J W Dankbaar
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands.
| | - T J Snijders
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - P A Robe
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - T Seute
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - W Eppinga
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - J Hendrikse
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands
| | - B De Keizer
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands
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12
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Gehrmann MK, Kimm MA, Stangl S, Schmid TE, Noël PB, Rummeny EJ, Multhoff G. Imaging of Hsp70-positive tumors with cmHsp70.1 antibody-conjugated gold nanoparticles. Int J Nanomedicine 2015; 10:5687-700. [PMID: 26392771 PMCID: PMC4572731 DOI: 10.2147/ijn.s87174] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Real-time imaging of small tumors is still one of the challenges in cancer diagnosis, prognosis, and monitoring of clinical outcome. Targeting novel biomarkers that are selectively expressed on a large variety of different tumors but not normal cells has the potential to improve the imaging capacity of existing methods such as computed tomography. Herein, we present a novel technique using cmHsp70.1 monoclonal antibody-conjugated spherical gold nanoparticles for quantification of the targeted uptake of gold nanoparticles into membrane Hsp70-positive tumor cells. Upon binding, cmHsp70.1-conjugated gold nanoparticles but not nanoparticles coupled to an isotype-matched IgG1 antibody or empty nanoparticles are rapidly taken up by highly malignant Hsp70 membrane-positive mouse tumor cells. After 24 hours, the cmHsp70.1-conjugated gold nanoparticles are found to be enriched in the perinuclear region. Specificity for membrane Hsp70 was shown by using an Hsp70 knockout tumor cell system. Toxic side effects of the cmHsp70.1-conjugated nanoparticles are not observed at a concentration of 1–10 µg/mL. Experiments are ongoing to evaluate whether cmHsp70.1 antibody-conjugated gold nanoparticles are suitable for the detection of membrane-Hsp70-positive tumors in vivo.
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Affiliation(s)
- Mathias K Gehrmann
- Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Melanie A Kimm
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Stefan Stangl
- Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Thomas E Schmid
- Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Peter B Noël
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Ernst J Rummeny
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Gabriele Multhoff
- Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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13
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Carlier T, Bailly C. State-Of-The-Art and Recent Advances in Quantification for Therapeutic Follow-Up in Oncology Using PET. Front Med (Lausanne) 2015; 2:18. [PMID: 26090365 PMCID: PMC4370108 DOI: 10.3389/fmed.2015.00018] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 03/09/2015] [Indexed: 12/28/2022] Open
Abstract
18F-fluoro-2-deoxyglucose (18F-FDG) positron emission tomography (PET) is an important tool in oncology. Its use has greatly progressed from initial diagnosis to staging and patient monitoring. The information derived from 18F-FDG-PET allowed the development of a wide range of PET quantitative analysis techniques ranging from simple semi-quantitative methods like the standardized uptake value (SUV) to “high order metrics” that require a segmentation step and additional image processing. In this review, these methods are discussed, focusing particularly on the available methodologies that can be used in clinical trials as well as their current applications in international consensus for PET interpretation in lymphoma and solid tumors.
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Affiliation(s)
- Thomas Carlier
- Nuclear Medicine Department, University Hospital , Nantes , France ; CRCNA, INSERM U892, CNRS UMR 6299 , Nantes , France
| | - Clément Bailly
- Nuclear Medicine Department, University Hospital , Nantes , France
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14
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Owens EA, Lee S, Choi J, Henary M, Choi HS. NIR fluorescent small molecules for intraoperative imaging. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2015; 7:828-38. [PMID: 25645081 DOI: 10.1002/wnan.1337] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 12/03/2014] [Accepted: 12/15/2014] [Indexed: 01/24/2023]
Abstract
Recent advances in bioimaging and nanomedicine have permitted the exploitation of molecular optical imaging in image-guided surgery; however, the parameters mediating optimum performance of contrast agents are not yet precisely determined. To develop ideal contrast agents for image-guided surgery, we need to consider the following criteria: (1) excitation and emission wavelengths in the near-infrared (NIR) window, (2) optimized optical characteristics for high in vivo performance, (3) overcoming or harnessing biodistribution and clearance, and (4) reducing nonspecific uptake. The design considerations should be focused on optimizing the optical and physicochemical property criteria. Biodistribution and clearance should first be considered because they mediate the fate of a contrast agent in the body such as how long after intravenous injection a contrast agent reaches the peak signal-to-background ratio (SBR) and how long the signal lasts (retention).
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Affiliation(s)
- Eric A Owens
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA
| | - Stephanie Lee
- Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - JungMun Choi
- Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Maged Henary
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA
| | - Hak Soo Choi
- Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA.,Department of Cogno-Mechatronics Engineering, Pusan National University, Busan, South Korea
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15
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Conti M. New prospects for PET in prostate cancer imaging: a physicist's viewpoint. EJNMMI Phys 2014; 1:11. [PMID: 26501453 PMCID: PMC6890878 DOI: 10.1186/2197-7364-1-11] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/31/2014] [Indexed: 11/12/2022] Open
Abstract
Prostate cancer is one of the most common forms of cancer among men. Early diagnosis, correct staging, accurate detection of metastasis, and monitoring of the therapy are the key tasks that could greatly benefit from medical imaging. After a review of the main developments in the field of positron emission tomography (PET) tracers for prostate cancer, the impact of improved PET instrumentation with good spatial resolution and high sensitivity is discussed, together with the latest development in PET technology: lutetium oxy-ortho-silicate (LSO) and lutetium-yttrium oxy-ortho-silicate (LYSO) scintillators, resolution recovery, and time-of-flight reconstruction. New directions and multiple approaches in PET instrumentation for prostate cancer are presented and discussed. In particular, improved hardware and noise suppressing reconstruction algorithms allow for higher detectability of small lesions and better spatial resolution in PET/computerized tomography (CT) and PET/magnetic resonance (MR). This can be beneficial for guiding biopsy and surgery and for accurate therapy monitoring.
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Affiliation(s)
- Maurizio Conti
- Siemens Healthcare Molecular Imaging, 810 Innovation Drive, Knoxville, TN, 37932, USA.
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