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Onishi Y, Hashimoto F, Ote K, Ota R. Whole Reconstruction-Free System Design for Direct Positron Emission Imaging From Image Generation to Attenuation Correction. IEEE Trans Med Imaging 2024; 43:1654-1663. [PMID: 38109238 DOI: 10.1109/tmi.2023.3344095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Direct positron emission imaging (dPEI), which does not require a mathematical reconstruction step, is a next-generation molecular imaging modality. To maximize the practical applicability of the dPEI system to clinical practice, we introduce a novel reconstruction-free image-formation method called direct μCompton imaging, which directly localizes the interaction position of Compton scattering from the annihilation photons in a three-dimensional space by utilizing the same compact geometry as that for dPEI, involving ultrafast time-of-flight radiation detectors. This unique imaging method not only provides the anatomical information about an object but can also be applied to attenuation correction of dPEI images. Evaluations through Monte Carlo simulation showed that functional and anatomical hybrid images can be acquired using this multimodal imaging system. By fusing the images, it is possible to simultaneously access various object data, which ensures the synergistic effect of the two imaging methodologies. In addition, attenuation correction improves the quantification of dPEI images. The realization of the whole reconstruction-free imaging system from image generation to quantitative correction provides a new perspective in molecular imaging.
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Hutt E, Jaber WA, Jellis C, Mountis MM, Cremer PC. Novel dietary protocol prior to 18F-fluorodeoxyglucose positron emission tomography to evaluate for cardiac sarcoidosis. J Nucl Cardiol 2021; 28:2190-2193. [PMID: 33051803 DOI: 10.1007/s12350-020-02392-x] [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: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 11/29/2022]
Abstract
The diagnosis of cardiac sarcoidosis (CS) is challenging. Recently, guidelines incorporated cardiac positron emission tomography (PET) with 18F-Fluorodeoxyglucose (F18-FDG) as a non-invasive diagnostic modality for the detection and follow-up of CS. However, this technique is dependent of patient dietary preparation to suppress physiological myocardial F18-FDG uptake. We present a case of possible CS which highlights a novel preparation protocol that facilitated appropriate myocardial suppression.
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Affiliation(s)
- Erika Hutt
- Cardiovascular Medicine Department, Cleveland Clinic Foundation, 9500 Euclid Ave, NA3-129, Cleveland, OH, USA.
| | - Wael A Jaber
- Cardiovascular Medicine Department, Cleveland Clinic Foundation, 9500 Euclid Ave, NA3-129, Cleveland, OH, USA
| | - Christine Jellis
- Cardiovascular Medicine Department, Cleveland Clinic Foundation, 9500 Euclid Ave, NA3-129, Cleveland, OH, USA
| | - Maria M Mountis
- Cardiovascular Medicine Department, Cleveland Clinic Foundation, 9500 Euclid Ave, NA3-129, Cleveland, OH, USA
| | - Paul C Cremer
- Cardiovascular Medicine Department, Cleveland Clinic Foundation, 9500 Euclid Ave, NA3-129, Cleveland, OH, USA
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Watts DP, Bordes J, Brown JR, Cherlin A, Newton R, Allison J, Bashkanov M, Efthimiou N, Zachariou NA. Photon quantum entanglement in the MeV regime and its application in PET imaging. Nat Commun 2021; 12:2646. [PMID: 33976168 PMCID: PMC8113573 DOI: 10.1038/s41467-021-22907-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 04/01/2021] [Indexed: 11/17/2022] Open
Abstract
Positron Emission Tomography (PET) is a widely-used imaging modality for medical research and clinical diagnosis. Imaging of the radiotracer is obtained from the detected hit positions of the two positron annihilation photons in a detector array. The image is degraded by backgrounds from random coincidences and in-patient scatter events which require correction. In addition to the geometric information, the two annihilation photons are predicted to be produced in a quantum-entangled state, resulting in enhanced correlations between their subsequent interaction processes. To explore this, the predicted entanglement in linear polarisation for the two photons was incorporated into a simulation and tested by comparison with experimental data from a cadmium zinc telluride (CZT) PET demonstrator apparatus. Adapted apparati also enabled correlation measurements where one of the photons had undergone a prior scatter process. We show that the entangled simulation describes the measured correlations and, through simulation of a larger preclinical PET scanner, illustrate a simple method to quantify and remove the unwanted backgrounds in PET using the quantum entanglement information alone.
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Affiliation(s)
- D P Watts
- Department of Physics, University of York, Heslington, York, UK.
| | - J Bordes
- Department of Physics, University of York, Heslington, York, UK
| | - J R Brown
- Department of Physics, University of York, Heslington, York, UK
| | - A Cherlin
- Kromek Group, Sedgefield, County Durham, UK
| | - R Newton
- Department of Physics, University of York, Heslington, York, UK
| | - J Allison
- Geant4 Associates International Ltd., Hebden Bridge, UK
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
| | - M Bashkanov
- Department of Physics, University of York, Heslington, York, UK
| | - N Efthimiou
- Department of Physics, University of York, Heslington, York, UK
- PET Research Centre, School of Health Sciences, University of Hull, Hull, UK
| | - N A Zachariou
- Department of Physics, University of York, Heslington, York, UK
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Abstract
Optical property modulation induced by ionizing radiation is a promising approach for ultra-fast, lower time jitter detection of photon arrival time. If successful, this method can be utilized in time-of-flight positron emission tomography to achieve a coincidence time resolution approaching 10 ps. In this work, the optical property modulation based method is further developed with focus on a detection setup based on two crossed polarizers. Previous work demonstrated that such an optical setup could be utilized in radiation detection, though its detection sensitivity needed improvement. This work investigates the angle between polarizers and electric field distribution within the detection crystal to understand and improve the detection sensitivity of an optical polarization modulation based method. For this work, cadmium telluride (CdTe) was studied as the detector crystal . The 'magic' angle (i.e. optimal working angle) of the two crossed polarizers based optical setup with CdTe were explored theoretically and experimentally. The experimental results show that the detection sensitivity could be improved by around 10% by determining the appropriate 'magic' angle. We then studied the dependence of detection sensitivity on electric field distribution as well as on the bias voltage across the detector crystal using CdTe crystals. The experimental results show that a smaller electrode on the detector crystal, or a more concentrated electric field distribution could improve detection sensitivity. For CdTe, a detector crystal sample with 2.5 mm × 2.5 mm square electrode has twice the detection sensitivity of a detector crystal with 5 mm × 5 mm square electrode. Increasing the bias voltage before saturation for CdTe could further enhance the modulation strength and thus, the sensitivity. Our investigations demonstrated that by determining the proper working angle of polarizers and bias electrical distribution to the detector, we could improve the sensitivity of the proposed optical setup.
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Affiliation(s)
- Yuli Wang
- Department of Electrical and Computer Engineering, University of California, Santa Cruz, Santa Cruz, CA, 95064, United States of America
| | - Li Tao
- Molecular Imaging Instrumentation Laboratory, Stanford University, Stanford, CA 94305, United States of America
| | - Shiva Abbaszadeh
- Department of Electrical and Computer Engineering, University of California, Santa Cruz, Santa Cruz, CA, 95064, United States of America
| | - Craig Levin
- Molecular Imaging Instrumentation Laboratory, Stanford University, Stanford, CA 94305, United States of America
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Abstract
We are exploring a scintillator-based PET detector with potential of high sensitivity, depth of interaction (DOI) capability, and timing resolution, with single-side readout. Our design combines two previous concepts: (1) multiple scintillator arrays stacked with relative offset, yielding inherent DOI information, but good timing performance has not been demonstrated with conventional light sharing readout. (2) Single crystal array with one-to-one coupling to the photodetector, showing superior timing performance compared to its light sharing counterparts, but lacks DOI. The combination, where the first layer of a staggered design is coupled one-to-one to a photodetector array, may provide both DOI and timing resolution and this concept is here evaluated through light transport simulations. Results show that: (1) unpolished crystal pixels in the staggered configuration yield better performance across all metrics compared to polished pixels, regardless of readout scheme. (2) One-to-one readout of the first layer allows for accurate DOI extraction using a single threshold. The number of multi pixel photon counter (MPPC) pixels with signal amplitudes exceeding the threshold corresponds to the interaction layer. This approach was not possible with conventional light sharing readout. (3) With a threshold of 2 optical photons, the layered approach with one-to-one coupled first layer improves timing close to the MPPC compared to the conventional one-to-one coupling non-DOI detector, due to effectively reduced crystal thickness. Single detector timing resolution values of 91, 127, 151 and 164 ps were observed per layer in the 4-layer design, to be compared to 148 ps for the single array with one-to-one coupling. (4) For the layered design with light sharing readout, timing improves with increased MPPC pixel size due to higher signal per channel. In conclusion, the combination of straightforward DOI determination, good timing performance, and relatively simple design makes the proposed concept promising for DOI-Time-of-Flight PET detectors.
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Affiliation(s)
- L Bläckberg
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
| | - S Sajedi
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
| | - G El Fakhri
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
| | - H Sabet
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
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Carter LM, Kesner AL, Pratt EC, Sanders VA, Massicano AVF, Cutler CS, Lapi SE, Lewis JS. The Impact of Positron Range on PET Resolution, Evaluated with Phantoms and PHITS Monte Carlo Simulations for Conventional and Non-conventional Radionuclides. Mol Imaging Biol 2021; 22:73-84. [PMID: 31001765 DOI: 10.1007/s11307-019-01337-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [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] [Indexed: 01/02/2023]
Abstract
PURPOSE The increasing interest and availability of non-standard positron-emitting radionuclides has heightened the relevance of radionuclide choice in the development and optimization of new positron emission tomography (PET) imaging procedures, both in preclinical research and clinical practice. Differences in achievable resolution arising from positron range can largely influence application suitability of each radionuclide, especially in small-ring preclinical PET where system blurring factors due to annihilation photon acollinearity and detector geometry are less significant. Some resolution degradation can be mitigated with appropriate range corrections implemented during image reconstruction, the quality of which is contingent on an accurate characterization of positron range. PROCEDURES To address this need, we have characterized the positron range of several standard and non-standard PET radionuclides (As-72, F-18, Ga-68, Mn-52, Y-86, and Zr-89) through imaging of small-animal quality control phantoms on a benchmark preclinical PET scanner. Further, the Particle and Heavy Ion Transport code System (PHITS v3.02) code was utilized for Monte Carlo modeling of positron range-dependent blurring effects. RESULTS Positron range kernels for each radionuclide were derived from simulation of point sources in ICRP reference tissues. PET resolution and quantitative accuracy afforded by various radionuclides in practicable imaging scenarios were characterized using a convolution-based method based on positron annihilation distributions obtained from PHITS. Our imaging and simulation results demonstrate the degradation of small animal PET resolution, and quantitative accuracy correlates with increasing positron energy; however, for a specific "benchmark" preclinical PET scanner and reconstruction workflow, these differences were observed to be minimal given radionuclides with average positron energies below ~ 400 keV. CONCLUSION Our measurements and simulations of the influence of positron range on PET resolution compare well with previous efforts documented in the literature and provide new data for several radionuclides in increasing clinical and preclinical use. The results will support current and future improvements in methods for positron range corrections in PET imaging.
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Affiliation(s)
- L M Carter
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Adam Leon Kesner
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - E C Pratt
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA
| | - V A Sanders
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, USA
| | - A V F Massicano
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - C S Cutler
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, USA
| | - S E Lapi
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jason S Lewis
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA.
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Department of Radiology, Weill Cornell Medical College, New York, NY, USA.
- Radiochemistry and Molecular Imaging Probes Core, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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Abstract
This article describes aspects of PET scanner design for long axial field-of-view systems and how these choices have an impact on scanner performance.
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Affiliation(s)
- Margaret E Daube-Witherspoon
- Department of Radiology, University of Pennsylvania, 3620 Hamilton Walk, Room 156H, Philadelphia, PA 19104, USA.
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California, 451 Health Sciences Drive, Davis, CA 95616, USA
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Abstract
Following successful performance testing and human imaging of a prototype PennPET Explorer, the scanner has been expanded to a current axial field of view of 1.12 m. Initial studies on this instrument have demonstrated encouraging results for total-body positron emission tomography imaging. Planned studies will test the capabilities of the PennPET Explorer further and inform the design of further human imaging protocols.
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Affiliation(s)
- Austin R Pantel
- University of Pennsylvania, 3620 Hamilton Walk, 154 John Morgan Building, Philadelphia, PA 19104, USA
| | - Varsha Viswanath
- University of Pennsylvania, 3620 Hamilton Walk, 154 John Morgan Building, Philadelphia, PA 19104, USA
| | - Joel S Karp
- University of Pennsylvania, 3620 Hamilton Walk, 154 John Morgan Building, Philadelphia, PA 19104, USA.
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Ahmadi A, Klein R, Lewin HC, Beanlands RSB, deKemp RA. Rubidium-82 generator yield and efficiency for PET perfusion imaging: Comparison of two clinical systems. J Nucl Cardiol 2020; 27:1728-1738. [PMID: 32436115 PMCID: PMC7599151 DOI: 10.1007/s12350-020-02200-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 04/18/2020] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Strontium-82/Rubidium-82 (82Sr/82Rb) generators are used widely for positron emission tomography (PET) imaging of myocardial perfusion. In this study, the 82Rb isotope yield and production efficiency of two FDA-approved 82Sr/82Rb generators were compared. METHODS N = 515 sequential daily quality assurance (QA) reports from 9 CardioGen-82® and 9 RUBY-FILL® generators were reviewed over a period of 2 years. A series of test elutions was performed at different flow-rates on the RUBY-FILL® system to determine an empirical correction-factor used to convert CardioGen-82® daily QA values of 82Rb activity (dose-calibrator 'maximum' of 50 mL elution at 50 mL·min-1) to RUBY-FILL® equivalent values (integrated 'total' of 35 mL elution at 20 mL·min-1). The generator yield (82Rb) and production efficiency (82Rb yield/82Sr parent activity) were measured and compared after this conversion to a common scale. RESULTS At the start of clinical use, the system reported 82Rb activity from daily QA was lower for CardioGen-82® vs RUBY-FILL® (2.3 ± 0.2 vs 3.0 ± 0.2 GBq, P < 0.001) despite having similar 82Sr activity. Dose-calibrator 'maximum' (CardioGen-82®) values were found to under-estimate the integrated 'total' (RUBY-FILL®) activity by ~ 24% at 50 mL·min-1. When these data were used to convert the CardioGen-82 values to a common measurement scale (integrated total activity) the CardioGen-82® efficiency remained slightly lower than the RUBY-FILL® system on average (88 ± 4% vs 95 ± 4%, P < 0.001). The efficiency of 82Rb production improved for both systems over the respective periods of clinical use. CONCLUSIONS 82Rb generator yield was significantly under-estimated using the CardioGen-82® vs RUBY-FILL® daily QA procedure. When generator yield was expressed as the integrated total activity for both systems, the estimated 82Rb production efficiency of the CardioGen-82® system was ~ 7% lower than RUBY-FILL® over the full period of clinical use.
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Affiliation(s)
- Ali Ahmadi
- Division of Cardiology, University of Ottawa Heart Institute, National Cardiac PET Centre, 40 Ruskin Street, Ottawa, ON, K1Y 4W7, Canada
| | - Ran Klein
- Division of Nuclear Medicine, The Ottawa Hospital, Ottawa, ON, Canada
| | - Howard C Lewin
- Cardiac Imaging Nuclear Associates, Los Angeles, CA, USA
| | - Rob S B Beanlands
- Division of Cardiology, University of Ottawa Heart Institute, National Cardiac PET Centre, 40 Ruskin Street, Ottawa, ON, K1Y 4W7, Canada
| | - Robert A deKemp
- Division of Cardiology, University of Ottawa Heart Institute, National Cardiac PET Centre, 40 Ruskin Street, Ottawa, ON, K1Y 4W7, Canada.
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LaBella A, Zhao W, Lubinsky R, Goldan AH. Prismatoid light guide array for enhanced gamma ray localization in PET: a Monte Carlo simulation study of scintillation photon transport. Phys Med Biol 2020; 65:18LT01. [PMID: 32413872 PMCID: PMC11025681 DOI: 10.1088/1361-6560/ab9373] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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] [Indexed: 11/11/2022]
Abstract
High spatial resolution PET relies on having excellent depth-of-interaction (DOI) resolution and small detector elements. Depth-encoding in PET modules has traditionally been performed using dual-ended readout. In recent years, researchers have explored the feasibility of replacing the second readout array with a light guide at the entrance layer that introduces intercrystal light sharing in order to reduce cost and and make depth-encoding modules more compact. However, single-ended readout depth-encoding modules have suboptimal and non-uniform crystal separation and DOI performance due to the random light sharing patterns of the uniform light guide, resulting in degraded peformance along the edges and corners of the detector arrays. In this paper, we introduce and characterize a segmented light guide composed of an array of prism mirrors which introduce deterministic intercrystal light sharing in single-ended readout PET detectors. We determined the expected spatial performance of our modules with our light guide using optical ray tracing Monte Carlo simulations. We demonstrate that having controlled, deterministic light sharing improves both DOI and crystal identification performance, enabling uniform spatial performance throughout the detector array. Designed specifically for high resolution PET, our prismatoid light guide array can be used to build cost-effective total-body and organ-dedicated PET systems with single-ended readout depth-encoding modules.
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Affiliation(s)
- Andy LaBella
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, United States of America
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11
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Abstract
We are building a high sensitivity preclinical PET/MRI insert using a highly multiplexed light sharing PET module. Each module incorporates four 19 × 19 arrays of 1 × 1 × 20 mm3 LYSO crystals with dual-ended DOI encoding readout, requiring 32 readout channels for positioning and eight channels for timing. These constraints necessitate compact, robust electronics for digitization. We have characterized four linearized time-over-threshold circuits based on these detector requirements. The four circuits allow for high channel density and can digitize signals from highly multiplexed light sharing detectors. Each circuit digitizes one channel of a multiplexed SiPM array, yielding a binary output that interfaces directly with an FPGA. Using the optimal circuit, we have characterized the performance of a pair of PET modules. The four circuits were characterized based on linearity of the 22Na photopeak positions and energy resolution at 511 keV, as well as separation of elements in a 10 × 10 array of 1.2 mm LYSO crystals coupled with a specular reflector. Practical measures of performance were comparable to those obtained with a DRS evaluation board, which served as a reference acquisition system. The ratio of the 22Na photopeak positions was 2.0 for each circuit and the reference system, implying 20% saturation due to the SiPM. PET energy resolution of the optimal circuit was 11.8% FWHM for a single crystal versus 12.6% for the reference system, and crystals were equally well separated in all cases. PCBs implementing the optimal readout circuit were fabricated and used to construct two complete detector modules. Crystals in each of the four blocks in the module were well resolved, with a mean energy resolution of 24.4 ± 4.7%. Two modules operating in coincidence showed a single detector timing resolution of 3.0 ns, which is appropriate for preclinical applications.
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Affiliation(s)
- Aaron Selfridge
- Department of Biomedical Engineering, University of California, Davis, United States of America
| | - Simon Cherry
- Department of Biomedical Engineering, University of California, Davis, United States of America
- Department of Radiology, University of California, Davis, United States of America
| | - Ramsey Badawi
- Department of Biomedical Engineering, University of California, Davis, United States of America
- Department of Radiology, University of California, Davis, United States of America
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Yin YG, Suzui N, Kurita K, Miyoshi Y, Unno Y, Fujimaki S, Nakamura T, Shinano T, Kawachi N. Visualising spatio-temporal distributions of assimilated carbon translocation and release in root systems of leguminous plants. Sci Rep 2020; 10:8446. [PMID: 32528026 PMCID: PMC7289824 DOI: 10.1038/s41598-020-65668-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 10/07/2019] [Accepted: 05/06/2020] [Indexed: 12/30/2022] Open
Abstract
The release of rhizodeposits differs depending on the root position and is closely related to the assimilated carbon (C) supply. Therefore, quantifying the C partitioning over a short period may provide crucial information for clarifying root-soil carbon metabolism. A non-invasive method for visualising the translocation of recently assimilated C into the root system inside the rhizobox was established using 11CO2 labelling and the positron-emitting tracer imaging system. The spatial distribution of recent 11C-photoassimilates translocated and released in the root system and soil were visualised for white lupin (Lupinus albus) and soybean (Glycine max). The inputs of the recently assimilated C in the entire root that were released into the soil were approximately 0.3%-2.9% for white lupin within 90 min and 0.9%-2.3% for soybean within 65 min, with no significant differences between the two plant species; however, the recently assimilated C of lupin was released at high concentrations in specific areas (hotspots), whereas that of soybean was released uniformly in the soil. Our method enabled the quantification of the spatial C allocations in roots and soil, which may help to elucidate the relationship between C metabolism and nutrient cycling at specific locations of the root-soil system in response to environmental conditions over relatively short periods.
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Affiliation(s)
- Yong-Gen Yin
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Gunma, 370-1292, Japan.
| | - Nobuo Suzui
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Gunma, 370-1292, Japan
| | - Keisuke Kurita
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Gunma, 370-1292, Japan
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
| | - Yuta Miyoshi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Gunma, 370-1292, Japan
| | - Yusuke Unno
- Department of Radioecology, Institute for Environmental Sciences, Aomori, 039-3212, Japan
| | - Shu Fujimaki
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Gunma, 370-1292, Japan
- Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Takuji Nakamura
- Agro-environmental Research Division, NARO Hokkaido Agricultural Research Center, Hokkaido, 062-8555, Japan
| | - Takuro Shinano
- Agricultural Radiation Research Center, NARO Tohoku Agricultural Research Center, Fukushima, 960-2156, Japan
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, 060-8589, Japan
| | - Naoki Kawachi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Gunma, 370-1292, Japan
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Valladares A, Beyer T, Rausch I. Physical imaging phantoms for simulation of tumor heterogeneity in PET, CT, and MRI: An overview of existing designs. Med Phys 2020; 47:2023-2037. [PMID: 31981214 PMCID: PMC7216968 DOI: 10.1002/mp.14045] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [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: 08/14/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND In oncology, lesion characterization is essential for tumor grading, treatment planning, and follow-up of cancer patients. Hybrid imaging systems, such as Single Photon Emission Computed Tomography (SPECT)/CT, Positron Emission Tomography (PET)/CT, or PET/magnetic resonance imaging (MRI), play an essential role for the noninvasive quantification of tumor characteristics. However, most of the existing approaches are challenged by intra- and intertumor heterogeneity. Novel quantitative imaging parameters that can be derived from textural feature analysis (as part of radiomics) are promising complements for improved characterization of tumor heterogeneity, thus, supporting clinically relevant implementations of personalized medicine concepts. Nevertheless, establishing new quantitative parameters for tumor characterization requires the use of standardized imaging objects to test the reliability of results prior to their implementation in patient studies. METHODS In this review, we summarize existing reports on heterogeneous phantoms with a focus on simulating tumor heterogeneity. We discuss the techniques, materials, advantages, and limitations of the existing phantoms for PET, CT, and MR imaging modalities. CONCLUSIONS Finally, we outline the future directions and requirements for the design of cross modality imaging phantoms.
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Affiliation(s)
- Alejandra Valladares
- QIMP TeamCentre for Medical Physics and Biomedical EngineeringMedical University of ViennaVienna1090Austria
| | - Thomas Beyer
- QIMP TeamCentre for Medical Physics and Biomedical EngineeringMedical University of ViennaVienna1090Austria
| | - Ivo Rausch
- QIMP TeamCentre for Medical Physics and Biomedical EngineeringMedical University of ViennaVienna1090Austria
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14
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Viswanath V, Daube Witherspoon ME, Karp JS, Surti S. Numerical observer study of lesion detectability for a long axial field-of-view whole-body PET imager using the PennPET Explorer. Phys Med Biol 2020; 65:035002. [PMID: 31816616 PMCID: PMC7261597 DOI: 10.1088/1361-6560/ab6011] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This work uses lesion detectability to characterize the performance of long axial field of view (AFOV) PET scanners which have increased sensitivity compared to clinical scanners. Studies were performed using the PennPET Explorer, a 70 cm long AFOV scanner built at the University of Pennsylvania, for small lesions distributed in a uniform water-filled cylinder (simulations and measurements), an anthropomorphic torso phantom (measurement), and a human subject (measurement). The lesion localization and detection task was quantified numerically using a generalized scan statistics methodology. Detectability was studied as a function of background activity distribution, scan duration for a single bed position, and axial location of the lesions. For the cylindrical phantom, the areas under the localization receiver operating curve (ALROCs) of lesions placed at various axial locations in the scanner were greater than 0.8-a value considered to be clinically acceptable (i.e. 80% probability of detecting lesion)-for scan times of 60 s or longer for standard-of-care (SoC) clinical dose levels. 10 mm diameter lesions placed in the anthropomorphic phantom and human subject resulted in ALROCs of 0.8 or greater for scan times longer than 30 s in the lung region and 60 s in the liver region, also for SoC doses. ALROC results from all three activity distributions show similar trends as a function of counts detected per axial location. These results will be used to guide decisions on imaging parameters, such as scan time and patient dose, when imaging patients in a single bed position on long AFOV systems and can also be applied to clinical scanners with consideration of the sensitivity differences.
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Affiliation(s)
- Varsha Viswanath
- Department of BioEngineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA 19104, United States of America. Author to whom any correspondence should be addressed
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15
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Kanno I, Takahashi M, Yamaya T. [Michel M. Ter-Pogossian (1925-1996): A pioneer of positron emission tomography weighted in fast imaging and Oxygen-15 application]. Igaku Butsuri 2020; 40:110. [PMID: 32999250 DOI: 10.11323/jjmp.40.3_110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
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16
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Yamauchi-Kawaura C, Fujii K, Yamauchi M, Yamamoto S, Kozuka M, Ohzawa N, Suga N, Ito N. SHAPE ESTIMATION OF BOWTIE FILTERS BASED ON THE LUMINESCENCE FROM POLYETHYLENE TEREPHTHALATE RESIN BY X-RAY IRRADIATION. Radiat Prot Dosimetry 2019; 185:432-439. [PMID: 30916354 DOI: 10.1093/rpd/ncz031] [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] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 01/27/2019] [Accepted: 02/28/2019] [Indexed: 06/09/2023]
Abstract
In this study, we devised a novel method estimating the bowtie filter shapes by imaging luminescence from a polyethylene terephthalate (PET) resin with X-ray irradiation in a computed tomography (CT) scanner. The luminescence distribution of the PET resin corresponding to the thickness of bowtie filter was imaged using a charge-coupled device camera. On the assumption that the material of bowtie filter is aluminium (Al), the shape of bowtie filters was estimated from the correlation between Al attenuation curves and the angular-dependent luminance attenuation profiles according to the thickness of bowtie filters. Dose simulations based on the estimated bowtie filter shapes were performed using head and body PMMA phantoms with 16 and 32 cm in diameter. The simulated values of head and body weighted CT dose index (CTDIw) based on bowtie filter shape by the luminescence imaging method agreed within ~9% with the measured values by a dosemeter.
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Affiliation(s)
- C Yamauchi-Kawaura
- Department of Radiological Sciences, Graduate School of Medicine, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
| | - K Fujii
- Department of Radiological Sciences, Graduate School of Medicine, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
| | - M Yamauchi
- Division of Radiology, Aichi Medical University Hospital, Nagakute, Aichi 480-1195, Japan
| | - S Yamamoto
- Department of Radiological Sciences, Graduate School of Medicine, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
| | - M Kozuka
- Department of Radiological Technology, School of Health Sciences, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
| | - N Ohzawa
- Department of Radiological Technology, School of Health Sciences, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
| | - N Suga
- Department of Radiological Technology, School of Health Sciences, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
| | - N Ito
- Department of Radiological Technology, School of Health Sciences, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
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17
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Cho ZH, Son YD, Kim HK, Kwon DH, Joo YH, Ra JB, Choi Y, Kim YB. Development of Positron Emission Tomography With Wobbling and Zooming for High Sensitivity and High-Resolution Molecular Imaging. IEEE Trans Med Imaging 2019; 38:2875-2882. [PMID: 31094686 DOI: 10.1109/tmi.2019.2916326] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Demands for in-vivo human molecular imaging with high resolution and high sensitivity in positron emission tomography (PET) require several new design formulae. A classical problem of the PET design, however, was the trade-off between sensitivity and resolution. To satisfy both requirements, the brain-body convertible PET with wobbling and zooming is proposed. The features of this new proposed system are wobble sampling for high-resolution imaging and zooming mode for high sensitivity, especially for the brain dedicated imaging. For the high resolution, wobbling with a linear interpolation and line spread function (LSF) deconvolution reconstruction algorithm was introduced. The result of the proposed system provided resolution up to 1.56 mm full width at half maximum (FWHM) in the brain mode and resulting in the detector-to-resolution ratio (DRR) was 2.47. For both brain phantom and in-vivo rat brain imaging, the proposed system demonstrated superior image quality compared with the commercial PET systems. The newly designed PET with wobbling and zooming also demonstrated the possibility of developing practically usable high-resolution human brain PET-MRI fusion system, especially for the neuroscience research.
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18
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Chen F, Ma K, Zhang L, Madajewski B, Turker MZ, Gallazzi F, Cruickshank K, Zhang X, Jenjitranant P, Touijer KA, Quinn TP, Zanzonico P, Wiesner U, Bradbury MS. Ultrasmall Renally Clearable Silica Nanoparticles Target Prostate Cancer. ACS Appl Mater Interfaces 2019; 11:43879-43887. [PMID: 31675204 PMCID: PMC7199444 DOI: 10.1021/acsami.9b15195] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [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] [Indexed: 05/29/2023]
Abstract
Although important advances have been achieved in the development of radiolabeled prostate-specific membrane antigen (PSMA)-targeting ligand constructs for both diagnosis and therapy of prostate cancer (PCa) over the past decade, challenges related to off-target effects and limited treatment responses persist. In this study, which builds upon the successful clinical translation of a series of ultrasmall, dye-encapsulating core-shell silica nanoparticles, or Cornell Prime Dots (C' dots), for cancer management, we sought to address these limitations by designing a dual-modality, PSMA-targeting platform that evades undesirable accumulations in the salivary glands, kidneys, and reticuloendothelial system, while exhibiting bulk renal clearance. This versatile PCa-targeted particle imaging probe offers significant clinical potential to improve future theranostic applications in a variety of patient care settings.
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Affiliation(s)
- Feng Chen
- Department of Radiology, Sloan Kettering Institute for Cancer Research, New York, New York 10065, United States
| | - Kai Ma
- Department of Materials Science & Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Li Zhang
- Department of Radiology, Sloan Kettering Institute for Cancer Research, New York, New York 10065, United States
| | - Brian Madajewski
- Department of Radiology, Sloan Kettering Institute for Cancer Research, New York, New York 10065, United States
| | - Melik Z. Turker
- Department of Materials Science & Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Fabio Gallazzi
- Department of Chemistry and Molecular Interactions Core, University of Missouri, Columbia, Missouri 65211, United States
| | - Kiara Cruickshank
- Department of Radiology, Sloan Kettering Institute for Cancer Research, New York, New York 10065, United States
| | - Xiuli Zhang
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Pocharapong Jenjitranant
- Department of Radiology, Sloan Kettering Institute for Cancer Research, New York, New York 10065, United States
| | - Karim A. Touijer
- Urology Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Thomas P. Quinn
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
- Harry S Truman Veterans’ Hospital, Columbia, Missouri 65201, United States
| | - Pat Zanzonico
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Ulrich Wiesner
- Department of Materials Science & Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Michelle S. Bradbury
- Department of Radiology, Sloan Kettering Institute for Cancer Research, New York, New York 10065, United States
- Molecular Pharmacology Program, Sloan Kettering Institute for Cancer Research, New York, New York 10065, United States
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19
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Morland D, Lalire P, Guendouzen S, Papathanassiou D, Passat N. A no-reference respiratory blur estimation index in nuclear medicine for image quality assessment. Medicine (Baltimore) 2019; 98:e18207. [PMID: 31770279 PMCID: PMC6890350 DOI: 10.1097/md.0000000000018207] [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] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Few indexes are available for nuclear medicine image quality assessment, particularly for respiratory blur assessment. A variety of methods for the identification of blur parameters has been proposed in literature mostly for photographic pictures but these methods suffer from a high sensitivity to noise, making them unsuitable to evaluate nuclear medicine images. In this paper, we aim to calibrate and test a new blur index to assess image quality.Blur index calibration was evaluated by numerical simulation for various lesions size and intensity of uptake. Calibrated blur index was then tested on gamma-camera phantom acquisitions, PET phantom acquisitions and real-patient PET images and compared to human visual evaluation.For an optimal filter parameter of 9, non-weighted and weighted blur index led to an automated classification close to the human one in phantom experiments and identified each time the sharpest image in all the 40 datasets of 4 images. Weighted blur index was significantly correlated to human classification (ρ = 0.69 [0.45;0.84] P < .001) when used on patient PET acquisitions.The provided index allows to objectively characterize the respiratory blur in nuclear medicine acquisition, whether in planar or tomographic images and might be useful in respiratory gating applications.
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Affiliation(s)
- David Morland
- Médecine Nucléaire, Institut Godinot
- Laboratoire de Biophysique, UFR de Médecine, Université de Reims Champagne Ardenne
- CRESTIC EA 3804, Université de Reims Champagne Ardenne
| | | | | | - Dimitri Papathanassiou
- Médecine Nucléaire, Institut Godinot
- Laboratoire de Biophysique, UFR de Médecine, Université de Reims Champagne Ardenne
- CRESTIC EA 3804, Université de Reims Champagne Ardenne
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20
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Hope TA, Fayad ZA, Fowler KJ, Holley D, Iagaru A, McMillan AB, Veit-Haiback P, Witte RJ, Zaharchuk G, Catana C. Summary of the First ISMRM-SNMMI Workshop on PET/MRI: Applications and Limitations. J Nucl Med 2019; 60:1340-1346. [PMID: 31123099 PMCID: PMC6785790 DOI: 10.2967/jnumed.119.227231] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [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: 02/08/2019] [Accepted: 05/21/2019] [Indexed: 12/12/2022] Open
Abstract
Since the introduction of simultaneous PET/MRI in 2011, there have been significant advancements. In this review, we highlight several technical advancements that have been made primarily in attenuation and motion correction and discuss the status of multiple clinical applications using PET/MRI. This review is based on the experience at the first PET/MRI conference cosponsored by the International Society for Magnetic Resonance in Medicine and the Society of Nuclear Medicine and Molecular Imaging.
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Affiliation(s)
- Thomas A Hope
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
- Department of Radiology, San Francisco VA Medical Center, San Francisco, California
- UCSF Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California
| | - Zahi A Fayad
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kathryn J Fowler
- Department of Radiology, University of California San Diego, San Diego, California
| | - Dawn Holley
- Department of Radiology, Stanford University Medical Center, Stanford, California
| | - Andrei Iagaru
- Department of Radiology, Stanford University Medical Center, Stanford, California
| | - Alan B McMillan
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Patrick Veit-Haiback
- Joint Department of Medical Imaging, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Canada
| | - Robert J Witte
- Department of Radiology, Mayo Clinic, Rochester, Minnesota; and
| | - Greg Zaharchuk
- Department of Radiology, Stanford University Medical Center, Stanford, California
| | - Ciprian Catana
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
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21
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Yang Y, Liu X, Qian H. [Analysis of Risk in Production for PET/MR and Suggestions for Field Inspection]. Zhongguo Yi Liao Qi Xie Za Zhi 2019; 43:365-368. [PMID: 31625338 DOI: 10.3969/j.issn.1671-7104.2019.05.015] [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] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
PET/MR is a high-end medical imaging equipment with integrating PET and MR equipment into the highly sophisticated one and has rich clinical and molecular diagnosis functions, can obtain comprehensive information about the human body structure, function and metabolism, is of great value for the diagnosis and treatment of disease improvement. In this paper, through the analysis of existing production risk points on one of the primary stages of the whole product life cycle, combining with the medical device good manufacture practice, some suggestions have been put forward exploratively to field inspection for PET/MR manufacturers. It has certain significance for regulators of medical devices to clear the production risk point and improve verification efficiency during field inspection.
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Affiliation(s)
- Yiqiang Yang
- Center for Certification & Evaluation, SHFDA, Shanghai, 200020
| | - Xin Liu
- Center for Certification & Evaluation, SHFDA, Shanghai, 200020
| | - Hong Qian
- Center for Certification & Evaluation, SHFDA, Shanghai, 200020
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22
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Ferrer L, Josset S, Moignier A, Delpon G. [Hybrid radiotherapy machines: Evolution or revolution?]. Cancer Radiother 2019; 23:761-764. [PMID: 31471254 DOI: 10.1016/j.canrad.2019.07.140] [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: 07/05/2019] [Accepted: 07/15/2019] [Indexed: 11/19/2022]
Abstract
The arrival of new hybrid radiotherapy machines with MRI or PET is announced as a milestone in radiotherapy management. Based on recent literature, we will describe the contribution of each of these modalities and the technological challenges that have already been or are still to be addressed.
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Affiliation(s)
- L Ferrer
- Service de physique médicale, institut de cancérologie de l'Ouest, boulevard Jacques-Monod, 44805 Saint-Herblain, France.
| | - S Josset
- Service de physique médicale, institut de cancérologie de l'Ouest, boulevard Jacques-Monod, 44805 Saint-Herblain, France
| | - A Moignier
- Service de physique médicale, institut de cancérologie de l'Ouest, boulevard Jacques-Monod, 44805 Saint-Herblain, France
| | - G Delpon
- Service de physique médicale, institut de cancérologie de l'Ouest, boulevard Jacques-Monod, 44805 Saint-Herblain, France
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23
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Abstract
This paper presents a unique preclinical positron emission tomography (PET) detector constructed with a monolithic scintillator ring (MSR) and two rings of silicon photomultipliers (SiPM). The inner diameter, outer diameter and length of the MSR were 48.5 mm, 58.5 mm, and 25.1 mm, respectively. The two SiPM rings, constructed with 46 SiPMs, were air-coupled to the two ends of the MSR detector. The center of gravity (COG) and artificial neural network (ANN) methods were adapted to decode the positions of the gamma interactions in the circumferential (θ) and axial (Z) directions, respectively. Collimating systems, consisting of a tungsten collimator and a high-precision displacement and rotating platform, were constructed to assess the decoding accuracies of the MSR detector in both θ and Z directions. The average intrinsic full-width half maximums (FWHMs) and mean absolute errors (MAEs) of the decoding accuracies were 0.94 mm and 0.33 mm in the circumferential direction, 2.45 mm and 1.08 mm in the axial direction. An energy resolution of 10.7% was measured at 511 keV. The scintillating photons generated by a pair of coincidence gamma photons overlap with each other, and cause circumferential parallax errors in the lines of response (LOR). The experimental results show that the average FWHM errors in the θ direction increased slightly from 0.94 mm to 1.14 mm when Δθ of the two single events was larger than 70°. The imaging performance of the MSR detector was also initially assessed with a Derenzo phantom filled with 18F-FDG. The rods with a diameter larger than 1.2 mm can be resolved. The energy resolutions were 12.3% at 511 keV (single events), and 11.4% at 1022 keV (coincidence events). We concluded that it is feasible to construct the high-performance preclinical PET scanners using one or multiple MSR detectors.
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Affiliation(s)
- Jianfeng Xu
- State Key Lab of Digital Manufacturing Equipment & Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Siwei Xie
- State Key Lab of Digital Manufacturing Equipment & Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
- Department of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Xi Zhang
- State Key Lab of Digital Manufacturing Equipment & Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Weijie Tao
- School of Biomedical Engineering, Shanghai Jiaotong University, Shanghai 200025, China
| | - Jingwu Yang
- State Key Lab of Digital Manufacturing Equipment & Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Zhixiang Zhao
- School of Biomedical Engineering, Shanghai Jiaotong University, Shanghai 200025, China
| | - Fenghua Weng
- School of Biomedical Engineering, Shanghai Jiaotong University, Shanghai 200025, China
| | - Qiu Huang
- School of Biomedical Engineering, Shanghai Jiaotong University, Shanghai 200025, China
| | - Fei Yi
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qiyu Peng
- Department of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Watanabe M, Nakamoto Y, Nakamoto R, Ishimori T, Saga T, Togashi K. Performance Evaluation of a Newly Developed MR-Compatible Mobile PET Scanner with Two Detector Layouts. Mol Imaging Biol 2019; 22:407-415. [PMID: 31222564 DOI: 10.1007/s11307-019-01384-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [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] [Indexed: 11/25/2022]
Abstract
PURPOSE A mobile positron emission tomography (PET) scanner called flexible PET (fxPET), designed to fit existing magnetic resonance imaging (MRI) or computed tomography (CT) system, has been developed. The purpose of this study was to evaluate the image quality, lesion detection rate, and quantitative values of fxPET compared with conventional bismuth germanium oxide (BGO)-based PET/CT without time-of-flight capability. PROCEDURES Fifty-nine patients underwent whole-body (WB) PET/CT scans approximately 1 h after injection of 2-deoxy-2-[18F]fluoro-D-glucose, followed by the fxPET scans with detectors located above and below the patients (layout A) and with detectors closer to the patients (layout B). Two readers assessed the image quality using a 4-point grade for each layout and reached a consensus. We evaluated the differences and/or correlations between fxPET and WB PET/CT, including the lesion detection rates, the standardized uptake value (SUV), the metabolic tumor volume (MTV), the total lesion glycolysis (TLG), the tumor-to-normal liver ratio (TLR), and the background liver signal-to-noise ratio (SNR). RESULTS The image quality of layout B was better than layout A (p < 0.0001). Of 184 lesions, the detection rate of layout B was significantly higher than WB PET/CT (p = 0.041), while the detection rate of layout A was comparable to WB PET/CT. The SUVmax/mean/peak were larger, and the MTVs were smaller in fxPET than WB PET/CT, especially in the lesions smaller than 2 cm (p < 0.01). The SUVmax/mean/peak, the MTVs and the TLGs of fxPET had significant positive correlations with WB PET/CT (p < 0.0001). The TLRs were significantly larger (p < 0.0001), but the background SNRs were significantly lower in fxPET than WB PET/CT (p < 0.05). CONCLUSIONS The fxPET system yielded reasonable image quality and quantitative accuracy. Bringing the detectors closer to the patient yielded improved results.
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Affiliation(s)
- Masao Watanabe
- Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoinkawahara-cho, Sakyo-Ku, Kyoto, 606-8507, Japan
| | - Yuji Nakamoto
- Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoinkawahara-cho, Sakyo-Ku, Kyoto, 606-8507, Japan.
| | - Ryusuke Nakamoto
- Department of Radiology, Shiga General Hospital, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan
| | - Takayoshi Ishimori
- Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoinkawahara-cho, Sakyo-Ku, Kyoto, 606-8507, Japan
| | - Tsuneo Saga
- Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoinkawahara-cho, Sakyo-Ku, Kyoto, 606-8507, Japan
| | - Kaori Togashi
- Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoinkawahara-cho, Sakyo-Ku, Kyoto, 606-8507, Japan
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Haddadifam T, Karami MA. A theoretical study of digital silicon photomultiplier utilization in diffuse optical imaging systems. BIOMED ENG-BIOMED TE 2019; 64:357-363. [PMID: 30001210 DOI: 10.1515/bmt-2018-0030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [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: 03/01/2018] [Accepted: 06/15/2018] [Indexed: 02/01/2023]
Abstract
Digital silicon photomultiplier (dSiPM) is introduced for diffuse optical imaging (DOI) applications instead of conventional photomultiplier tubes and avalanche photodiodes (APDs) as a state-of-the-art detector. According to the low-level light regime in DOI applications, high sensitivity and high dynamic range (DR) image sensors are needed for DOI systems. dSiPM is proposed as a developing detector which can detect low-level lights. Also, an accurate equation is obtained for calculating the DR of dSiPMs. Different dSiPMs and the corresponding benefits are studied for DOI applications. Furthermore, a 120 dB DR dSiPM is chosen for use in DOI systems. It is shown that dSiPMs can be utilized in DOI configurations such as time domain (TD), frequency domain (FD) and continuous wave (CW) systems. Ultimately, by utilizing dSiPM in DOI systems, the DOI method can be used for thoracic imaging due to the high DR and signal-to-noise ratio (SNR) of the detector.
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Affiliation(s)
- Taha Haddadifam
- School of Electrical Engineering, Iran University of Science and Technology (IUST), Tehran, Iran
| | - Mohammad Azim Karami
- School of Electrical Engineering, Iran University of Science and Technology (IUST), Tehran 1684613114, Iran, Phone: +982173225773
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26
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Abstract
In most high-resolution PET detector designs, there is an inherent trade-off between spatial resolution and detector efficiency. We have developed and tested a new geometry for the detector module which avoids this trade-off. The module uses a layered structure, in which four crystal slabs are stacked in the depth direction and optically separated by enhanced specular reflector (ESR) film. The scintillation light within each layer is measured by 16 SiPMs located on the four sides of the crystal. Analog signals from all SiPMs (4 × 16) on the four sides of the crystal are digitized individually using a 64-channel TOFPET-2 module. The four-sided readout method reduces the problem of light trapping resulting from total internal reflection when reading out the end(s) of traditional scintillation crystal arrays, thus increasing the light collection efficiency. In this work, we demonstrate the readout of a complete layered detector with 4 layers. The high light collection efficiency results in a FWHM energy resolution of 10.3%, and a FWHM timing resolution of 348 ps. The distribution of scintillation light detected by the SiPMs was used to decode the interaction position of each gamma ray using a trained neural network. A FWHM spatial resolution of 1.1 ± 0.1 mm was achieved. This design allows the detection efficiency of the module to be increased by adding additional crystal slabs along the depth direction. Since the position, energy, and timing are measured for each layer independently, increasing the system sensitivity by adding more layers will not affect the spatial/energy/timing resolution. Furthermore, the layered structure allows partial recovery of position information for events that undergo Compton scatter within the detector.
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Affiliation(s)
- Peng Peng
- Author to whom any correspondence should be addressed
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27
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Abstract
Advances in imaging instrumentation and technology have greatly contributed to nuclear cardiology. Dedicated cardiac SPECT cameras incorporating novel, highly efficient detector, collimator, and system designs have emerged with the expansion of nuclear cardiology. Solid-state radiation detectors incorporating cadmium zinc telluride, which directly convert radiation to electrical signals and yield improved energy resolution and spatial resolution and enhanced count sensitivity geometries, are increasingly gaining favor as the detector of choice for application in dedicated cardiac SPECT systems. Additionally, hybrid imaging systems in which SPECT and PET are combined with X-ray CT are currently widely used, with PET/MRI hybrid systems having also been recently introduced. The improved quantitative SPECT/CT has the potential to measure the absolute quantification of myocardial blood flow and flow reserve. Rapid development of silicon photomultipliers leads to enhancement in PET image quality and count rates. In addition, the reduction of emission-transmission mismatch artifacts via application of accurate time-of-flight information, and cardiac motion de-blurring aided by anatomical images, are emerging techniques for further improvement of cardiac PET. This article reviews recent advances such as these in nuclear cardiology imaging instrumentation and technology, and the corresponding diagnostic benefits.
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Affiliation(s)
- Jae Sung Lee
- Department of Nuclear Medicine, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
| | | | - Tali Sharir
- Department of Nuclear Cardiology, Assuta Medical Centers, 96 Igal Alon, C Building, 67891, Tel Aviv, Israel.
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Dong Soo Lee
- Department of Nuclear Medicine, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Korea.
- Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, Korea.
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28
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Yamamoto H, Takemoto S, Maebatake A, Karube S, Yamashiro Y, Nakanishi A, Murakami K. Verification of image quality and quantification in whole-body positron emission tomography with continuous bed motion. Ann Nucl Med 2019; 33:288-294. [PMID: 30707349 DOI: 10.1007/s12149-019-01334-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [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: 09/05/2018] [Accepted: 01/14/2019] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Whole-body dynamic imaging using positron emission tomography (PET) facilitates the quantification of tracer kinetics. It is potentially valuable for the differential diagnosis of tumors and for the evaluation of therapeutic efficacy. In whole-body dynamic PET with continuous bed motion (CBM) (WBDCBM-PET), the pass number and bed velocity are key considerations. In the present study, we aimed to investigate the effect of a combination of pass number and bed velocity on the quantitative accuracy and quality of WBDCBM-PET images. METHODS In this study, WBDCBM-PET imaging was performed at a body phantom using seven bed velocity settings in combination with pass numbers. The resulting image quality was evaluated. For comparing different acquisition settings, the dynamic index (DI) was obtained using the following formula: [P/S], where P represents the pass number, and S represents the bed velocity (mm/s). The following physical parameters were evaluated: noise equivalent count at phantom (NECphantom), percent background variability (N10 mm), percent contrast of the 10 mm hot sphere (QH, 10 mm), the QH, 10 mm/N10 mm ratio, and the maximum standardized uptake value (SUVmax). Furthermore, visual evaluation was performed. RESULTS The NECphantom was equivalent for the same DI settings regardless of the bed velocity. The N10 mm exhibited an inverse correlation (r < - 0.89) with the DI. QH,10 mm was not affected by DI, and a correlation between QH,10 mm/N10 mm ratio and DI was found at all the velocities (r > 0.93). The SUVmax of the spheres was not influenced by the DI. The coefficient of variations caused by bed velocity decreased in larger spheres. There was no significant difference between the bed velocities on visual evaluation. CONCLUSION The quantitative accuracy and image quality achieved with WBDCBM-PET was comparable to that achieved with non-dynamic CBM, regardless of the pass number and bed velocity used during imaging for a given acquisition time.
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Affiliation(s)
- Hideo Yamamoto
- Department of Radiology, Juntendo University School of Medicine, 3-1-3, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| | - Shota Takemoto
- Department of Radiology, Juntendo University School of Medicine, 3-1-3, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Akira Maebatake
- Department of Radiology, Juntendo University School of Medicine, 3-1-3, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Shuhei Karube
- Department of Radiology, Juntendo University School of Medicine, 3-1-3, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Yuki Yamashiro
- Department of Radiology, Juntendo University School of Medicine, 3-1-3, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Atsushi Nakanishi
- Department of Radiology, Juntendo University School of Medicine, 3-1-3, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Koji Murakami
- Department of Radiology, Juntendo University School of Medicine, 3-1-3, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
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Won JY, Lee JS. Highly Integrated FPGA-Only Signal Digitization Method Using Single-Ended Memory Interface Input Receivers for Time-of-Flight PET Detectors. IEEE Trans Biomed Circuits Syst 2018; 12:1401-1409. [PMID: 30113901 DOI: 10.1109/tbcas.2018.2865581] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We propose a new highly integrated field-programm-able gate array (FPGA) only signal digitization method for individual signal digitization of time-of-flight positron emission tomography (TOF PET). We configured I/O port of the FPGA with a single-ended memory interface (SeMI) input receiver. The SeMI is a single-ended voltage-referenced interface that has a common reference voltage per I/O Bank, such that each SeMI input receiver can serve as a voltage comparator. The FPGA-only digitizer that uses the single-ended input receivers does not require a separate digitizing integrated chip, and can obtain twice as many signals as that using LVDS input receivers. We implemented a highly integrated digitizer consisting of 82 energy and 82 timing channels using a 28-nm FPGA. The energy and arrival time were measured using a 625-ps binary counter, and a 10-ps time-to-digital converter (TDC), respectively. We first measured the intrinsic characteristics of the proposed FPGA-only digitizer. The SeMI input receiver functioned as the voltage comparator without undesirable offset voltage. The standard deviation value of the time difference measured using two SeMI input receivers with respective TDCs was less than 14.6 ps RMS. In addition, we fed signals from the TOF PET detectors to the SeMI input receivers directly and collected data. The TOF PET detector consisted of a 3 × 3 × 20 mm3 LYSO crystal coupled with a silicon photomultiplier. The energy resolutions were 7.7% and 7.1% for two TOF PET detectors. The coincidence resolving time was 204 ps full width at half maximum. The SeMI digitizer with a high-performance signal digitizer, processor, and high-speed transceivers provides a compact all-in-one data acquisition system.
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Yang CT, Ghosh KK, Padmanabhan P, Langer O, Liu J, Eng DNC, Halldin C, Gulyás B. PET-MR and SPECT-MR multimodality probes: Development and challenges. Theranostics 2018; 8:6210-6232. [PMID: 30613293 PMCID: PMC6299694 DOI: 10.7150/thno.26610] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 06/08/2018] [Indexed: 12/22/2022] Open
Abstract
Positron emission tomography (PET)-magnetic resonance (MR) or single photon emission computed tomography (SPECT)-MR hybrid imaging is being used in daily clinical practice. Due to its advantages over stand-alone PET, SPECT or MR imaging, in many areas such as oncology, the demand for hybrid imaging techniques is increasing dramatically. The use of multimodal imaging probes or biomarkers in a single molecule or particle to characterize the imaging subjects such as disease tissues certainly provides us with more accurate diagnosis and promotes therapeutic accuracy. A limited number of multimodal imaging probes are being used in preclinical and potential clinical investigations. The further development of multimodal PET-MR and SPECT-MR imaging probes includes several key elements: novel synthetic strategies, high sensitivity for accurate quantification and high anatomic resolution, favourable pharmacokinetic profile and target-specific binding of a new probe. This review thoroughly summarizes all recently available and noteworthy PET-MR and SPECT-MR multimodal imaging probes including small molecule bimodal probes, nano-sized bimodal probes, small molecular trimodal probes and nano-sized trimodal probes. To the best of our knowledge, this is the first comprehensive overview of all PET-MR and SPECT-MR multimodal probes. Since the development of multimodal PET-MR and SPECT-MR imaging probes is an emerging research field, a selection of 139 papers were recognized following the literature review. The challenges for designing multimodal probes have also been addressed in order to offer some future research directions for this novel interdisciplinary research field.
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Affiliation(s)
- Chang-Tong Yang
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921
- Cixi Institute of Biomedical Engineering, Ningbo Institute of Industrial Technology and Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, P.R. China, 315201
- Department of Nuclear Medicine and Molecular Imaging, Radiological Sciences Division, Singapore General Hospital, Outram Road, Singapore 169608
| | - Krishna K. Ghosh
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921
| | - Parasuraman Padmanabhan
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921
| | - Oliver Langer
- Department of Clinical Pharmacology and Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, A-1090, Vienna, Austria
- Center for Health and Bioresources, Biomedical Systems, AIT Austrian Institute of Technology GmbH, Seibersdorf, Austria
| | - Jiang Liu
- Cixi Institute of Biomedical Engineering, Ningbo Institute of Industrial Technology and Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, P.R. China, 315201
| | - David Ng Chee Eng
- Department of Nuclear Medicine and Molecular Imaging, Radiological Sciences Division, Singapore General Hospital, Outram Road, Singapore 169608
- Duke-NUS Medical School, 8 College Road, Singapore 169857
| | - Christer Halldin
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921
- Karolinska Institutet, Department of Clinical Neuroscience, S-171 76, Stockholm, Sweden
| | - Balázs Gulyás
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore 636921
- Karolinska Institutet, Department of Clinical Neuroscience, S-171 76, Stockholm, Sweden
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Korcyl G, Bialas P, Curceanu C, Czerwinski E, Dulski K, Flak B, Gajos A, Glowacz B, Gorgol M, Hiesmayr BC, Jasinska B, Kacprzak K, Kajetanowicz M, Kisielewska D, Kowalski P, Kozik T, Krawczyk N, Krzemien W, Kubicz E, Mohammed M, Niedzwiecki S, Pawlik-Niedzwiecka M, Palka M, Raczynski L, Rajda P, Rudy Z, Salabura P, Sharma NG, Sharma S, Shopa RY, Skurzok M, Silarski M, Strzempek P, Wieczorek A, Wislicki W, Zaleski R, Zgardzinska B, Zielinski M, Moskal P. Evaluation of Single-Chip, Real-Time Tomographic Data Processing on FPGA SoC Devices. IEEE Trans Med Imaging 2018; 37:2526-2535. [PMID: 29994248 DOI: 10.1109/tmi.2018.2837741] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A novel approach to tomographic data processing has been developed and evaluated using the Jagiellonian positron emission tomography scanner as an example. We propose a system in which there is no need for powerful, local to the scanner processing facility, capable to reconstruct images on the fly. Instead, we introduce a field programmable gate array system-on-chip platform connected directly to data streams coming from the scanner, which can perform event building, filtering, coincidence search, and region-of-response reconstruction by the programmable logic and visualization by the integrated processors. The platform significantly reduces data volume converting raw data to a list-mode representation, while generating visualization on the fly.
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Lee BJ, Watkins RD, Lee KS, Chang CM, Levin CS. Performance evaluation of RF coils integrated with an RF-penetrable PET insert for simultaneous PET/MRI. Magn Reson Med 2018; 81:1434-1446. [PMID: 30260501 DOI: 10.1002/mrm.27444] [Citation(s) in RCA: 9] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 05/01/2018] [Accepted: 06/11/2018] [Indexed: 01/19/2023]
Abstract
PURPOSE An "RF-penetrable" PET insert that allows the MR body coil to be used for RF transmission was developed to make it easier for an existing MR center to achieve simultaneous PET/MRI. This study focuses on experiments and analyses to study PET/RF coil configurations for simultaneous PET/MR studies. METHODS To investigate the appropriate RF coil design, a transmit/receive (TX/RX) birdcage coil and an RX-only phased-array coil (TX from body coil), both fitting inside the PET ring were built and characterized. For MR performance evaluation, B1 field uniformity and MR image SNR were calculated. PET photon attenuation due to each coil was studied by means of CT-based attenuation maps and reconstructed PET images. RESULTS When using the RX-only phased-array coil (TX from body coil), compared with the TX/RX birdcage coil, the B1 field uniformity and the MR image (gradient echo and fast spin echo) SNR increased by 2.4±4.8%, 386.1±62.3%, and 205.0±56.5%, respectively. Although some components of the coil were distributed within the PET FOV, no significant PET photon attenuation was shown in the CT-based attenuation map and reconstructed PET images. CONCLUSION RF coil configurations for an RF-penetrable PET insert for simultaneous PET/MRI were studied. The RX-only phased-array coil (TX from body coil) outperformed the TX/RX birdcage coil with improved MR performance as well as negligible PET photon attenuation.
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Affiliation(s)
- Brian J Lee
- Department of Radiology, Stanford University, Stanford, California
- Department of Mechanical Engineering, Stanford University, Stanford, California
| | - Ronald D Watkins
- Department of Radiology, Stanford University, Stanford, California
| | - Keum Sil Lee
- Department of Radiology, Stanford University, Stanford, California
| | - Chen-Ming Chang
- Department of Radiology, Stanford University, Stanford, California
- Department of Applied Physics, Stanford University, Stanford, California
| | - Craig S Levin
- Department of Radiology, Stanford University, Stanford, California
- Department of Bioengineering, Stanford University, Stanford, California
- Department of Electrical Engineering, Stanford University, Stanford, California
- Department of Physics, Stanford University, Stanford, California
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Lee BJ, Grant AM, Chang CM, Watkins RD, Glover GH, Levin CS. MR Performance in the Presence of a Radio Frequency-Penetrable Positron Emission Tomography (PET) Insert for Simultaneous PET/MRI. IEEE Trans Med Imaging 2018; 37:2060-2069. [PMID: 29993864 PMCID: PMC6195123 DOI: 10.1109/tmi.2018.2815620] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Despite the great promise of integrated positron emission tomography (PET)/magnetic resonance (MR) imaging to add molecular information to anatomical and functional MR, its potential impact in medicine is diminished by a very high cost, limiting its dissemination. An RF-penetrable PET ring that can be inserted into any existing MR system has been developed to address this issue. Employing optical signal transmission along with battery power enables the PET ring insert to electrically float with respect to the MR system. Then, inter-modular gaps of the PET ring allow the RF transmit field from the standard built-in body coil to penetrate into the PET fields-of-view (FOV) with some attenuation that can be compensated for. MR performance, including RF noise, magnetic susceptibility, RF penetrability through and $B_{1}$ uniformity within the PET insert, and MR image quality, were analyzed with and without the PET ring present. The simulated and experimentally measured RF field attenuation factors with the PET ring present were -2.7 and -3.2 dB, respectively. The magnetic susceptibility effect (0.063 ppm) and noise emitted from the PET ring in the MR receive channel were insignificant. $B_{1}$ homogeneity of a spherical agar phantom within the PET ring FOV dropped by 8.4% and MR image SNR was reduced by 3.5 and 4.3 dB with the PET present for gradient-recalled echo and fast-spin echo, respectively. This paper demonstrates, for the first time, an RF-penetrable PET insert comprising a full ring of operating detectors that achieves simultaneous PET/MR using the standard built-in body coil as the RF transmitter.
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Abstract
The hybrid PET/MR scanner represents the first implementation of the effective integration of two modalities allowing truly synchronous/simultaneous acquisition of their imaging signals. This integration, resulting from the innovation and development of specific hardware components has paved the way for new approaches in the study of neurodegenerative diseases. This chapter will describe the hardware development that has led to the availability of different clinical solutions for PET/MR imaging as well as the still-open technological challenges and opportunities related to the processing and exploitation of the simultaneous acquisition in neurological studies.
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Affiliation(s)
| | | | | | | | - Enrico De Vita
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, King's Health Partners, St Thomas' Hospital, London, United Kingdom
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Mannheim JG, Schmid AM, Pichler BJ. Influence of Co-57 and CT Transmission Measurements on the Quantification Accuracy and Partial Volume Effect of a Small Animal PET Scanner. Mol Imaging Biol 2018; 19:825-836. [PMID: 28361250 DOI: 10.1007/s11307-017-1074-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [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] [Indexed: 11/30/2022]
Abstract
PURPOSE Non-invasive in vivo positron emission tomography (PET) provides high detection sensitivity in the nano- to picomolar range and in addition to other advantages, the possibility to absolutely quantify the acquired data. The present study focuses on the comparison of transmission data acquired with an X-ray computed tomography (CT) scanner or a Co-57 source for the Inveon small animal PET scanner (Siemens Healthcare, Knoxville, TN, USA), as well as determines their influences on the quantification accuracy and partial volume effect (PVE). A special focus included the impact of the performed calibration on the quantification accuracy. PROCEDURES Phantom measurements were carried out to determine the quantification accuracy, the influence of the object size on the quantification, and the PVE for different sphere sizes, along the field of view and for different contrast ratios. RESULTS An influence of the emission activity on the Co-57 transmission measurements was discovered (deviations up to 24.06 % measured to true activity), whereas no influence of the emission activity on the CT attenuation correction was identified (deviations <3 % for measured to true activity). The quantification accuracy was substantially influenced by the applied calibration factor and by the object size. The PVE demonstrated a dependency on the sphere size, the position within the field of view, the reconstruction and correction algorithms and the count statistics. Depending on the reconstruction algorithm, only ∼30-40 % of the true activity within a small sphere could be resolved. The iterative 3D reconstruction algorithms uncovered substantially increased recovery values compared to the analytical and 2D iterative reconstruction algorithms (up to 70.46 % and 80.82 % recovery for the smallest and largest sphere using iterative 3D reconstruction algorithms). The transmission measurement (CT or Co-57 source) to correct for attenuation did not severely influence the PVE. CONCLUSIONS The analysis of the quantification accuracy and the PVE revealed an influence of the object size, the reconstruction algorithm and the applied corrections. Particularly, the influence of the emission activity during the transmission measurement performed with a Co-57 source must be considered. To receive comparable results, also among different scanner configurations, standardization of the acquisition (imaging parameters, as well as applied reconstruction and correction protocols) is necessary.
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Affiliation(s)
- Julia G Mannheim
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Roentgenweg 13, 72076, Tuebingen, Germany.
| | - Andreas M Schmid
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Roentgenweg 13, 72076, Tuebingen, Germany
| | - Bernd J Pichler
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Roentgenweg 13, 72076, Tuebingen, Germany
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Abstract
PET scanners are sophisticated and highly sensitive biomedical imaging devices that can produce highly quantitative images showing the 3-dimensional distribution of radiotracers inside the body. PET scanners are commonly integrated with x-ray CT or MRI scanners in hybrid devices that can provide both molecular imaging (PET) and anatomical imaging (CT or MRI). Despite decades of development, significant opportunities still exist to make major improvements in the performance of PET systems for a variety of clinical and research tasks. These opportunities stem from new ideas and concepts, as well as a range of enabling technologies and methodologies. In this paper, we review current state of the art in PET instrumentation, detectors and systems, describe the major limitations in PET as currently practiced, and offer our own personal insights into some of the recent and emerging technological innovations that we believe will impact the field. Our focus is on the technical aspects of PET imaging, specifically detectors and system design, and the opportunity and necessity to move closer to PET systems for diagnostic patient use and in vivo biomedical research that truly approach the physical performance limits while remaining mindful of imaging time, radiation dose, and cost. However, other key endeavors, which are not covered here, including innovations in reconstruction and modeling methodology, radiotracer development, and expanding the range of clinical and research applications, also will play an equally important, if not more important, role in defining the future of the field.
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Affiliation(s)
- Eric Berg
- Department of Biomedical Engineering, University of California, Davis, CA
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California, Davis, CA.; Department of Radiology, University of California, Davis, CA.
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Abstract
The aim of this study is to evaluate the benefit of long axial field-of-view (AFOV) PET scanners on region of interest (ROI) quantification. We simulated a series of PET scanners with an AFOV ranging from 22 cm to 220 cm. A theoretical framework was used to predict the contrast recovery coefficient (CRC) and the variance of ROI quantification in penalized maximum likelihood (ML) image reconstruction, in which the resolution and noise tradeoff was controlled by a regularization parameter with a quadratic penalty function. The characterization was based on the converged penalized ML reconstruction with an accurate system model. We examined quantification of a 2 mm ROI and 10 mm ROI in a clinically relevant scan range of 110 cm. Multiple bed positions with 50% overlap were used for scanners with shorter AFOV to provide a relatively uniform sensitivity across the 110 cm axial range. A uniform water cylinder of 20 cm in diameter and 230 cm in length was chosen to model the attenuation and background activity. We computed the variance reduction factor at fixed resolution. Effects of different detector capabilities, including TOF (time-of-flight) resolution (320 ps, 500 ps, and non-TOF) and DOI (depth-of-interaction) resolution (4 mm, 10 mm, and no DOI), were evaluated. The results show that at a normal activity level (370 MBq), the 220 cm AFOV scanner offers a ∼17-fold variance reduction for the 2 mm ROI and ∼26-fold variance reduction for the 10 mm ROI (both measured at CRC = 0.5) over the 22 cm AFOV scanner when both using detectors with 500 ps TOF resolution no DOI capability. The variance reduction factors of trues-only are higher than those of including scatters and randoms. Combining 320 ps TOF and 4 mm DOI, the 220 cm long scanner offers a ∼45-fold variance reduction over the 22 cm long reference scanner (500 ps TOF, no DOI) for imaging 2 mm and 10 mm ROIs. The variance reduction factors are higher at a lower activity level due to lower random fraction. In conclusion, our study demonstrates that a long AFOV scanner can greatly improve the quantitative accuracy of PET imaging compared to current state-of-the-art clinical PET scanners.
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Affiliation(s)
- Xuezhu Zhang
- Department of Biomedical Engineering, University of California, Davis, California, United States
| | - Ramsey D. Badawi
- Department of Biomedical Engineering, University of California, Davis, California, United States
- Department of Radiology, University of California, Davis, California, United States
| | - Simon R. Cherry
- Department of Biomedical Engineering, University of California, Davis, California, United States
- Department of Radiology, University of California, Davis, California, United States
| | - Jinyi Qi
- Department of Biomedical Engineering, University of California, Davis, California, United States
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Fricke IB, De Souza R, Costa Ayub L, Francia G, Kerbel R, Jaffray DA, Zheng J. Spatiotemporal assessment of spontaneous metastasis formation using multimodal in vivo imaging in HER2+ and triple negative metastatic breast cancer xenograft models in mice. PLoS One 2018; 13:e0196892. [PMID: 29723251 PMCID: PMC5933713 DOI: 10.1371/journal.pone.0196892] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/20/2018] [Indexed: 12/31/2022] Open
Abstract
Background Preclinical breast cancer models recapitulating the clinical course of metastatic disease are crucial for drug development. Highly metastatic cell lines forming spontaneous metastasis following orthotopic implantation were previously developed and characterized regarding their biological and histological characteristics. This study aimed to non-invasively and longitudinally characterize the spatiotemporal pattern of metastasis formation and progression in the MDA-MB-231-derived triple negative LM2-4 and HER2+ LM2-4H2N cell lines, using bioluminescence imaging (BLI), contrast enhanced computed tomography (CT), fluorescence imaging, and 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron emission tomography ([18F]FDG-PET). Material and methods LM2-4, LM2-4H2N, and MDA-MB-231 tumors were established in the right inguinal mammary fat pad (MFP) of female SCID mice and resected 14–16 days later. Metastasis formation was monitored using BLI. Metabolic activity of primary and metastatic lesions in mice bearing LM2-4 or LM2-4H2N was assessed by [18F]FDG-PET. Metastatic burden at study endpoint was assessed by CT and fluorescence imaging following intravenous dual-modality liposome agent administration. Results Comparable temporal metastasis patterns were observed using BLI for the highly metastatic cell lines LM2-4 and LM2-4H2N, while metastasis formed about 10 days later for MDA-MB-231. 21 days post primary tumor resection, metastases were detected in 86% of LM2-4, 69% of LM2-4H2N, and 60% of MDA-MB-231 inoculated mice, predominantly in the axillary region, contralateral MFP, and liver/lung. LM2-4 and LM2-4H2N tumors displayed high metabolism based on [18F]FDG-PET uptake. Lung metastases were detected as the [18F]FDG-PET uptake increased significantly between pre- and post-metastasis scan. Using a liposomal dual-modality agent, CT and fluorescence confirmed BLI detected lesions and identified additional metastatic nodules in the intraperitoneal cavity and lung. Conclusions The combination of complementary anatomical and functional imaging techniques can provide high sensitivity characterization of metastatic disease spread, progression and overall disease burden. The described models and imaging toolset can be implemented as an effective means for quantitative treatment response evaluation in metastatic breast cancer.
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Affiliation(s)
- Inga B. Fricke
- TECHNA Institute for the Advancement of Technology for Health, University Health Network, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
| | - Raquel De Souza
- TECHNA Institute for the Advancement of Technology for Health, University Health Network, Toronto, Ontario, Canada
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Lais Costa Ayub
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Giulio Francia
- Biological Sciences Platform, Sunnybrook Research Institute, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Robert Kerbel
- Biological Sciences Platform, Sunnybrook Research Institute, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - David A. Jaffray
- TECHNA Institute for the Advancement of Technology for Health, University Health Network, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada
| | - Jinzi Zheng
- TECHNA Institute for the Advancement of Technology for Health, University Health Network, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
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Mou T, Huang J, O'Sullivan F. The Gamma Characteristic of Reconstructed PET Images: Implications for ROI Analysis. IEEE Trans Med Imaging 2018; 37:1092-1102. [PMID: 29727273 DOI: 10.1109/tmi.2017.2770147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The basic emission process associated with positron emission tomography (PET) imaging is Poisson in nature. Reconstructed images inherit some aspects of this-regional variability is typically proportional to the regional mean. Iterative reconstruction using expectation-maximization (EM), widely used in clinical imaging now, imposes positivity constraints that impact noise properties. This paper is motivated by the analysis of data from a physical phantom study of a PET/CT scanner in routine clinical use. Both traditional filtered back-projection (FBP) and EM reconstructions of the images are considered. FBP images are quite Gaussian, but the EM reconstructions exhibit Gamma-like skewness. The Gamma structure has implications for how reconstructed PET images might be processed statistically. Post-reconstruction inference-model fitting and diagnostics for regions of interest are of particular interest. Although the relevant Gamma parameterization is not within the framework of generalized linear models (GLM), iteratively re-weighted least squares (IRLS) techniques, which are often used to find the maximum likelihood estimates of a GLM, can be adapted for analysis in this setting. This paper highlights the use of a Gamma-based probability transform in producing normalized residuals as model diagnostics. The approach is demonstrated for quality assurance analyses associated with physical phantom studies-recovering estimates of local bias and variance characteristics in an operational scanner. Numerical simulations show that when the Gamma assumption is reasonable, gains in efficiency are obtained. This paper shows that the adaptation of standard analysis methods to accommodate the Gamma structure is straightforward and beneficial.
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Hsu DFC, Freese DL, Reynolds PD, Innes DR, Levin CS. Design and Performance of a 1 mm 3 Resolution Clinical PET System Comprising 3-D Position Sensitive Scintillation Detectors. IEEE Trans Med Imaging 2018; 37:1058-1066. [PMID: 29621003 DOI: 10.1109/tmi.2018.2799619] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We are developing a 1-mm3 resolution, high-sensitivity positron emission tomography (PET) system for loco-regional cancer imaging. The completed system will comprise two cm detector panels and contain 4 608 position sensitive avalanche photodiodes (PSAPDs) coupled to arrays of mm3 LYSO crystal elements for a total of 294 912 crystal elements. For the first time, this paper summarizes the design and reports the performance of a significant portion of the final clinical PET system, comprising 1 536 PSAPDs, 98 304 crystal elements, and an active field-of-view (FOV) of cm. The sub-system performance parameters, such as energy, time, and spatial resolutions are predictive of the performance of the final system due to the modular design. Analysis of the multiplexed crystal flood histograms shows 84% of the crystal elements have>99% crystal identification accuracy. The 511 keV photopeak energy resolution was 11.34±0.06% full-width half maximum (FWHM), and coincidence timing resolution was 13.92 ± 0.01 ns FWHM at 511 keV. The spatial resolution was measured using maximum likelihood expectation maximization reconstruction of a grid of point sources suspended in warm background. The averaged resolution over the central 6 cm of the FOV is 1.01 ± 0.13 mm in the X-direction, 1.84 ± 0.20 mm in the Y-direction, and 0.84 ± 0.11 mm in the Z-direction. Quantitative analysis of acquired micro-Derenzo phantom images shows better than 1.2 mm resolution at the center of the FOV, with subsequent resolution degradation in the y-direction toward the edge of the FOV caused by limited angle tomography effects.
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Pierce LA, Pedemonte S, DeWitt D, MacDonald L, Hunter WCJ, Van Leemput K, Miyaoka R. Characterization of highly multiplexed monolithic PET / gamma camera detector modules. Phys Med Biol 2018; 63:075017. [PMID: 29498361 PMCID: PMC5908720 DOI: 10.1088/1361-6560/aab380] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PET detectors use signal multiplexing to reduce the total number of electronics channels needed to cover a given area. Using measured thin-beam calibration data, we tested a principal component based multiplexing scheme for scintillation detectors. The highly-multiplexed detector signal is no longer amenable to standard calibration methodologies. In this study we report results of a prototype multiplexing circuit, and present a new method for calibrating the detector module with multiplexed data. A [Formula: see text] mm3 LYSO scintillation crystal was affixed to a position-sensitive photomultiplier tube with [Formula: see text] position-outputs and one channel that is the sum of the other 64. The 65-channel signal was multiplexed in a resistive circuit, with 65:5 or 65:7 multiplexing. A 0.9 mm beam of 511 keV photons was scanned across the face of the crystal in a 1.52 mm grid pattern in order to characterize the detector response. New methods are developed to reject scattered events and perform depth-estimation to characterize the detector response of the calibration data. Photon interaction position estimation of the testing data was performed using a Gaussian Maximum Likelihood estimator and the resolution and scatter-rejection capabilities of the detector were analyzed. We found that using a 7-channel multiplexing scheme (65:7 compression ratio) with 1.67 mm depth bins had the best performance with a beam-contour of 1.2 mm FWHM (from the 0.9 mm beam) near the center of the crystal and 1.9 mm FWHM near the edge of the crystal. The positioned events followed the expected Beer-Lambert depth distribution. The proposed calibration and positioning method exhibited a scattered photon rejection rate that was a 55% improvement over the summed signal energy-windowing method.
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Affiliation(s)
- L A Pierce
- Imaging Research Laboratory, Department of Radiology, University of Washington, 1959 NE Pacific St., Seattle WA, United States of America
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Du J, Bai X, Gola A, Acerbi F, Ferri A, Piemonte C, Yang Y, Cherry SR. Performance of a high-resolution depth-encoding PET detector module using linearly-graded SiPM arrays. Phys Med Biol 2018; 63:035035. [PMID: 29324437 PMCID: PMC5823499 DOI: 10.1088/1361-6560/aaa707] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The goal of this study was to exploit the excellent spatial resolution characteristics of a position-sensitive silicon photomultiplier (SiPM) and develop a high-resolution depth-of-interaction (DOI) encoding positron emission tomography (PET) detector module. The detector consists of a 30 × 30 array of 0.445 × 0.445 × 20 mm3 polished LYSO crystals coupled to two 15.5 × 15.5 mm2 linearly-graded SiPM (LG-SiPM) arrays at both ends. The flood histograms show that all the crystals in the LYSO array can be resolved. The energy resolution, the coincidence timing resolution and the DOI resolution were 21.8 ± 5.8%, 1.23 ± 0.10 ns and 3.8 ± 1.2 mm, respectively, at a temperature of -10 °C and a bias voltage of 35.0 V. The performance did not degrade significantly for event rates of up to 130 000 counts s-1. This detector represents an attractive option for small-bore PET scanner designs that simultaneously emphasize high spatial resolution and high detection efficiency, important, for example, in preclinical imaging of the rodent brain with neuroreceptor ligands.
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Affiliation(s)
- Junwei Du
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, CA 95616, United States of America
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Abstract
Although there have been impressive strides in detector development for time-of-flight positron emission tomography, most detectors still make use of simple signal processing methods to extract the time-of-flight information from the detector signals. In most cases, the timing pick-off for each waveform is computed using leading edge discrimination or constant fraction discrimination, as these were historically easily implemented with analog pulse processing electronics. However, now with the availability of fast waveform digitizers, there is opportunity to make use of more of the timing information contained in the coincident detector waveforms with advanced signal processing techniques. Here we describe the application of deep convolutional neural networks (CNNs), a type of machine learning, to estimate time-of-flight directly from the pair of digitized detector waveforms for a coincident event. One of the key features of this approach is the simplicity in obtaining ground-truth-labeled data needed to train the CNN: the true time-of-flight is determined from the difference in path length between the positron emission and each of the coincident detectors, which can be easily controlled experimentally. The experimental setup used here made use of two photomultiplier tube-based scintillation detectors, and a point source, stepped in 5 mm increments over a 15 cm range between the two detectors. The detector waveforms were digitized at 10 GS s-1 using a bench-top oscilloscope. The results shown here demonstrate that CNN-based time-of-flight estimation improves timing resolution by 20% compared to leading edge discrimination (231 ps versus 185 ps), and 23% compared to constant fraction discrimination (242 ps versus 185 ps). By comparing several different CNN architectures, we also showed that CNN depth (number of convolutional and fully connected layers) had the largest impact on timing resolution, while the exact network parameters, such as convolutional filter size and number of feature maps, had only a minor influence.
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Affiliation(s)
- Eric Berg
- Department of Biomedical Engineering, University of California-Davis, Davis, CA, United States of America
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Cabello J, Ziegler SI. Advances in PET/MR instrumentation and image reconstruction. Br J Radiol 2018; 91:20160363. [PMID: 27376170 PMCID: PMC5966194 DOI: 10.1259/bjr.20160363] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Revised: 06/26/2016] [Accepted: 06/29/2016] [Indexed: 12/15/2022] Open
Abstract
The combination of positron emission tomography (PET) and MRI has attracted the attention of researchers in the past approximately 20 years in small-animal imaging and more recently in clinical research. The combination of PET/MRI allows researchers to explore clinical and research questions in a wide number of fields, some of which are briefly mentioned here. An important number of groups have developed different concepts to tackle the problems that PET instrumentation poses to the exposition of electromagnetic fields. We have described most of these research developments in preclinical and clinical experiments, including the few commercial scanners available. From the software perspective, an important number of algorithms have been developed to address the attenuation correction issue and to exploit the possibility that MRI provides for motion correction and quantitative image reconstruction, especially parametric modelling of radiopharmaceutical kinetics. In this work, we give an overview of some exemplar applications of simultaneous PET/MRI, together with technological hardware and software developments.
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Affiliation(s)
- Jorge Cabello
- Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Sibylle I Ziegler
- Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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Ahmed AM, Tashima H, Yamaya T. Investigation of spatial resolution improvement by use of a mouth-insert detector in the helmet PET scanner. Radiol Phys Technol 2017; 11:7-12. [PMID: 28986818 DOI: 10.1007/s12194-017-0425-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [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: 04/24/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 11/26/2022]
Abstract
The dominant factor limiting the intrinsic spatial resolution of a positron emission tomography (PET) system is the size of the crystal elements in the detector. To increase sensitivity and achieve high spatial resolution, it is essential to use advanced depth-of-interaction (DOI) detectors and arrange them close to the subject. The DOI detectors help maintain high spatial resolution by mitigating the parallax error caused by the thickness of the scintillator near the peripheral regions of the field-of-view. As an optimal geometry for a brain PET scanner, with high sensitivity and spatial resolution, we proposed and developed the helmet-chin PET scanner using 54 four-layered DOI detectors consisting of a 16 × 16 × 4 array of GSOZ scintillator crystals with dimensions of 2.8 × 2.8 × 7.5 mm3. All the detectors used in the helmet-chin PET scanner had the same spatial resolution. In this study, we conducted a feasibility study of a new add-on detector arrangement for the helmet PET scanner by replacing the chin detector with a segmented crystal cube, having high spatial resolution in all directions, which can be placed inside the mouth. The crystal cube (which we have named the mouth-insert detector) has an array of 20 × 20 × 20 LYSO crystal segments with dimensions of 1 × 1 × 1 mm3. Thus, the scanner is formed by the combination of the helmet and mouth-insert detectors, and is referred to as the helmet-mouth-insert PET scanner. The results show that the helmet-mouth-insert PET scanner has comparable sensitivity and improved spatial resolution near the center of the hemisphere, compared to the helmet-chin PET scanner.
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Affiliation(s)
- Abdella M Ahmed
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
| | - Hideaki Tashima
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Taiga Yamaya
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
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Abstract
Accurate and robust tomographic reconstruction from dynamic positron emission tomography (PET) acquired data is a difficult problem. Conventional methods, such as the maximum likelihood expectation maximization (MLEM) algorithm for reconstructing the activity distribution-based on individual frames, may lead to inaccurate results due to the checkerboard effect and limitation of photon counts. In this paper, we propose a stacked sparse auto-encoder based reconstruction framework for dynamic PET imaging. The dynamic reconstruction problem is formulated in a deep learning representation, where the encoding layers extract the prototype features, such as edges, so that, in the decoding layers, the reconstructed results are obtained through a combination of those features. The qualitative and quantitative results of the procedure, including the data based on a Monte Carlo simulation and real patient data demonstrates the effectiveness of our method.
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Affiliation(s)
- Jianan Cui
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China
| | - Xin Liu
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzheng, China
| | - Yile Wang
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China
| | - Huafeng Liu
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China
- * E-mail:
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Rajkumar R, Rota Kops E, Mauler J, Tellmann L, Lerche C, Herzog H, Shah NJ, Neuner I. Simultaneous trimodal PET-MR-EEG imaging: Do EEG caps generate artefacts in PET images? PLoS One 2017; 12:e0184743. [PMID: 28902890 PMCID: PMC5597218 DOI: 10.1371/journal.pone.0184743] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [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: 08/25/2016] [Accepted: 08/30/2017] [Indexed: 11/24/2022] Open
Abstract
Trimodal simultaneous acquisition of positron emission tomography (PET), magnetic resonance imaging (MRI), and electroencephalography (EEG) has become feasible due to the development of hybrid PET-MR scanners. To capture the temporal dynamics of neuronal activation on a millisecond-by-millisecond basis, an EEG system is appended to the quantitative high resolution PET-MR imaging modality already established in our institute. One of the major difficulties associated with the development of simultaneous trimodal acquisition is that the components traditionally used in each modality can cause interferences in its counterpart. The mutual interferences of MRI components and PET components on PET and MR images, and the influence of EEG electrodes on functional MRI images have been studied and reported on. Building on this, this study aims to investigate the influence of the EEG cap on the quality and quantification of PET images acquired during simultaneous PET-MR measurements. A preliminary transmission scan study on the ECAT HR+ scanner, using an Iida phantom, showed visible attenuation effect due to the EEG cap. The BrainPET-MR emission images of the Iida phantom with [18F]Fluordeoxyglucose, as well as of human subjects with the EEG cap, did not show significant effects of the EEG cap, even though the applied attenuation correction did not take into account the attenuation of the EEG cap itself.
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Affiliation(s)
- Ravichandran Rajkumar
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
- Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany
- JARA – BRAIN – Translational Medicine, Juelich, Germany
| | - Elena Rota Kops
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
| | - Jörg Mauler
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
| | - Lutz Tellmann
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
| | - Christoph Lerche
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
| | - Hans Herzog
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
| | - N. Jon Shah
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
- JARA – BRAIN – Translational Medicine, Juelich, Germany
- Department of Neurology, RWTH Aachen University, Aachen, Germany
- Department of Electrical and Computer Systems Engineering, and Monash Biomedical Imaging, School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Irene Neuner
- Institute of Neuroscience and Medicine 4 (INM4), Forschungszentrum Juelich, Juelich, Germany
- Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany
- JARA – BRAIN – Translational Medicine, Juelich, Germany
- * E-mail:
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Abbasi J. Total-Body PET Scanner Prototype Due Next Year. JAMA 2017; 318:116. [PMID: 28697236 DOI: 10.1001/jama.2017.8300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Lau JMC, Laforest R, Sotoudeh H, Nie X, Sharma S, McConathy J, Novak E, Priatna A, Gropler RJ, Woodard PK. Evaluation of attenuation correction in cardiac PET using PET/MR. J Nucl Cardiol 2017; 24:839-846. [PMID: 26499770 PMCID: PMC6360086 DOI: 10.1007/s12350-015-0197-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [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: 02/22/2015] [Revised: 05/16/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND Simultaneous acquisition Positron emission tomography/magnetic resonance (PET/MR) is a new technology that has potential as a tool both in research and clinical diagnosis. However, cardiac PET acquisition has not yet been validated using MR imaging for attenuation correction (AC). The goal of this study is to evaluate the feasibility of PET imaging using a standard 2-point Dixon volume interpolated breathhold examination (VIBE) MR sequence for AC. METHODS AND RESULTS Evaluation was performed in both phantom and patient data. A chest phantom containing heart, lungs, and a lesion insert was scanned by both PET/MR and PET/CT. In addition, 30 patients underwent whole-body 18F-fluorodeoxyglucose PET/CT followed by simultaneous cardiac PET/MR. Phantom study showed 3% reduction of activity values in the myocardium due to the non-inclusion of the phased array coil in the AC. In patient scans, average standardized uptake values (SUVs) obtained by PET/CT and PET/MR showed no significant difference (n = 30, 4.6 ± 3.5 vs 4.7 ± 2.8, P = 0.47). There was excellent per patient correlation between the values acquired by PET/CT and PET/MR (R 2 = 0.97). CONCLUSIONS Myocardial SUVs PET imaging using MR for AC shows excellent correlation with myocardial SUVs obtained by standard PET/CT imaging. The 2-point Dixon VIBE MR technique can be used for AC in simultaneous PET/MR data acquisition.
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Affiliation(s)
- Jeffrey M C Lau
- Division of Cardiovascular Disease, Department of Internal Medicine, Washington University in Saint Louis, Campus Box 8086, 660 S. Euclid Avenue, Saint Louis, MO, 63110, USA.
| | - R Laforest
- Department of Radiological Sciences, Mallinckrodt Institute of Radiology, Washington University in Saint Louis, Saint Louis, MO, USA
| | - H Sotoudeh
- Department of Radiological Sciences, Mallinckrodt Institute of Radiology, Washington University in Saint Louis, Saint Louis, MO, USA
| | - X Nie
- Department of Radiological Sciences, Mallinckrodt Institute of Radiology, Washington University in Saint Louis, Saint Louis, MO, USA
| | - S Sharma
- Division of Cardiovascular Disease, Department of Internal Medicine, Washington University in Saint Louis, Campus Box 8086, 660 S. Euclid Avenue, Saint Louis, MO, 63110, USA
| | - J McConathy
- Department of Radiological Sciences, Mallinckrodt Institute of Radiology, Washington University in Saint Louis, Saint Louis, MO, USA
| | - E Novak
- Division of Cardiovascular Disease, Department of Internal Medicine, Washington University in Saint Louis, Campus Box 8086, 660 S. Euclid Avenue, Saint Louis, MO, 63110, USA
| | - A Priatna
- Siemens Medical Solutions U.S.A, Malvern, PA, USA
| | - R J Gropler
- Department of Radiological Sciences, Mallinckrodt Institute of Radiology, Washington University in Saint Louis, Saint Louis, MO, USA
| | - P K Woodard
- Department of Radiological Sciences, Mallinckrodt Institute of Radiology, Washington University in Saint Louis, Saint Louis, MO, USA
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Matheoud R, Lecchi M, Lizio D, Scabbio C, Marcassa C, Leva L, Del Sole A, Rodella C, Indovina L, Bracco C, Brambilla M, Zoccarato O. Comparative analysis of iterative reconstruction algorithms with resolution recovery and time of flight modeling for 18F-FDG cardiac PET: A multi-center phantom study. J Nucl Cardiol 2017; 24:1036-1045. [PMID: 26758376 DOI: 10.1007/s12350-015-0385-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 07/08/2015] [Accepted: 08/21/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND The purpose of this study was to evaluate the image quality in cardiac 18F-FDG PET using the time of flight (TOF) and/or point spread function (PSF) modeling in the iterative reconstruction (IR). METHODS Three scanners and an anthropomorphic cardiac phantom with an insert simulating a transmural defect (TD) were used. Two sets of scans (with/without TD) were acquired, and four reconstruction schemes were considered: (1) IR; (2) IR + PSF, (3) IR + TOF, and (4) IR + TOF + PSF. LV wall thickness (FWHM), contrast between LV wall and inner chamber (C IC), and TD contrast in LV wall (C TD) were evaluated. RESULTS Tests of the reconstruction protocols showed a decrease in FWHM from IR (13 mm) to IR + PSF (11 mm); an increase in the C IC from IR (65%) to IR + PSF (71%) and from IR + TOF (72%) to IR + TOF + PSF (77%); and an increase in the C TD from IR + PSF (72%) to IR + TOF (75%) and to IR + TOF + PSF (77%). Tests of the scanner/software combinations showed a decrease in FWHM from Gemini_TF (13 mm) to Biograph_mCT (12 mm) and to Discovery_690 (11 mm); an increase in the C IC from Gemini_TF (65%) to Biograph_mCT (73%) and to Discovery_690 (75%); and an increase in the C TD from Gemini_TF/Biograph_mCT (72%) to Discovery_690 (77%). CONCLUSION The introduction of TOF and PSF increases image quality in cardiac 18F-FDG PET. The scanner/software combinations exhibit different performances, which should be taken into consideration when making cross comparisons.
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Affiliation(s)
- Roberta Matheoud
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy
| | - Michela Lecchi
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
| | - Domenico Lizio
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy
| | - Camilla Scabbio
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
| | - Claudio Marcassa
- Unit of Nuclear Medicine and Department of Cardiology, S. Maugeri Foundation, IRCCS, Veruno, Italy
| | - Lucia Leva
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy
| | - Angelo Del Sole
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
| | - Carlo Rodella
- Health Physics Unit, Spedali Civili Hospital, Brescia, Italy
| | - Luca Indovina
- Department of Medical Physics, Polyclinic Agostino Gemelli, Rome, Italy
| | - Christian Bracco
- Medical Physics Department, Institute for Cancer Research and Treatment, Candiolo, Italy
| | - Marco Brambilla
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy.
| | - Orazio Zoccarato
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
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