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Li H, Badawi RD, Cherry SR, Fontaine K, He L, Henry S, Hillmer AT, Hu L, Khattar N, Leung EK, Li T, Li Y, Liu C, Liu P, Lu Z, Majewski S, Matuskey D, Morris ED, Mulnix T, Omidvari N, Samanta S, Selfridge A, Sun X, Toyonaga T, Volpi T, Zeng T, Jones T, Qi J, Carson RE. Performance Characteristics of the NeuroEXPLORER, a Next-Generation Human Brain PET/CT Imager. J Nucl Med 2024; 65:1320-1326. [PMID: 38871391 PMCID: PMC11294061 DOI: 10.2967/jnumed.124.267767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/13/2024] [Indexed: 06/15/2024] Open
Abstract
The collaboration of Yale, the University of California, Davis, and United Imaging Healthcare has successfully developed the NeuroEXPLORER, a dedicated human brain PET imager with high spatial resolution, high sensitivity, and a built-in 3-dimensional camera for markerless continuous motion tracking. It has high depth-of-interaction and time-of-flight resolutions, along with a 52.4-cm transverse field of view (FOV) and an extended axial FOV (49.5 cm) to enhance sensitivity. Here, we present the physical characterization, performance evaluation, and first human images of the NeuroEXPLORER. Methods: Measurements of spatial resolution, sensitivity, count rate performance, energy and timing resolution, and image quality were performed adhering to the National Electrical Manufacturers Association (NEMA) NU 2-2018 standard. The system's performance was demonstrated through imaging studies of the Hoffman 3-dimensional brain phantom and the mini-Derenzo phantom. Initial 18F-FDG images from a healthy volunteer are presented. Results: With filtered backprojection reconstruction, the radial and tangential spatial resolutions (full width at half maximum) averaged 1.64, 2.06, and 2.51 mm, with axial resolutions of 2.73, 2.89, and 2.93 mm for radial offsets of 1, 10, and 20 cm, respectively. The average time-of-flight resolution was 236 ps, and the energy resolution was 10.5%. NEMA sensitivities were 46.0 and 47.6 kcps/MBq at the center and 10-cm offset, respectively. A sensitivity of 11.8% was achieved at the FOV center. The peak noise-equivalent count rate was 1.31 Mcps at 58.0 kBq/mL, and the scatter fraction at 5.3 kBq/mL was 36.5%. The maximum count rate error at the peak noise-equivalent count rate was less than 5%. At 3 iterations, the NEMA image-quality contrast recovery coefficients varied from 74.5% (10-mm sphere) to 92.6% (37-mm sphere), and background variability ranged from 3.1% to 1.4% at a contrast of 4.0:1. An example human brain 18F-FDG image exhibited very high resolution, capturing intricate details in the cortex and subcortical structures. Conclusion: The NeuroEXPLORER offers high sensitivity and high spatial resolution. With its long axial length, it also enables high-quality spinal cord imaging and image-derived input functions from the carotid arteries. These performance enhancements will substantially broaden the range of human brain PET paradigms, protocols, and thereby clinical research applications.
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Affiliation(s)
- Hongdi Li
- United Imaging Healthcare North America, Houston, Texas
| | | | | | | | - Liuchun He
- United Imaging Healthcare, Shanghai, China
| | | | | | - Lingzhi Hu
- United Imaging Healthcare North America, Houston, Texas
| | | | - Edwin K Leung
- United Imaging Healthcare North America, Houston, Texas
- University of California, Davis, Davis, California
| | - Tiantian Li
- United Imaging Healthcare North America, Houston, Texas
- University of California, Davis, Davis, California
| | - Yusheng Li
- United Imaging Healthcare North America, Houston, Texas
| | - Chi Liu
- Yale University, New Haven, Connecticut; and
| | - Peng Liu
- United Imaging Healthcare, Shanghai, China
| | - Zhenrui Lu
- United Imaging Healthcare, Shanghai, China
| | | | | | | | - Tim Mulnix
- Yale University, New Haven, Connecticut; and
| | | | | | - Aaron Selfridge
- United Imaging Healthcare North America, Houston, Texas
- University of California, Davis, Davis, California
| | - Xishan Sun
- United Imaging Healthcare North America, Houston, Texas
| | | | | | - Tianyi Zeng
- Yale University, New Haven, Connecticut; and
| | - Terry Jones
- University of California, Davis, Davis, California
| | - Jinyi Qi
- University of California, Davis, Davis, California
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Vrachliotis A, Gaitanis A, Protonotarios NE, Kastis GA, Costaridou L. Noninvasive Quantification of Glucose Metabolism in Mice Myocardium Using the Spline Reconstruction Technique. J Imaging 2024; 10:170. [PMID: 39057741 PMCID: PMC11278115 DOI: 10.3390/jimaging10070170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 06/25/2024] [Accepted: 07/12/2024] [Indexed: 07/28/2024] Open
Abstract
The spline reconstruction technique (SRT) is a fast algorithm based on a novel numerical implementation of an analytic representation of the inverse Radon transform. The purpose of this study was to compare the SRT, filtered back-projection (FBP), and the Tera-Tomo 3D algorithm for various iteration numbers, using small-animal dynamic PET data obtained from a Mediso nanoScan® PET/CT scanner. For this purpose, Patlak graphical kinetic analysis was employed to noninvasively quantify the myocardial metabolic rate of glucose (MRGlu) in seven male C57BL/6 mice (n=7). All analytic reconstructions were performed via software for tomographic image reconstruction. The analysis of all PET-reconstructed images was conducted with PMOD software (version 3.506, PMOD Technologies LLC, Fällanden, Switzerland) using the inferior vena cava as the image-derived input function. Statistical significance was determined by employing the one-way analysis of variance test. The results revealed that the differences between the values of MRGlu obtained via SRT versus FBP, and the variants of he Tera-Tomo 3D algorithm were not statistically significant (p > 0.05). Overall, the SRT appears to perform similarly to the other algorithms investigated, providing a valid alternative analytic method for preclinical dynamic PET studies.
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Affiliation(s)
- Alexandros Vrachliotis
- Department of Medical Physics, School of Medicine, University of Patras, 26504 Patras, Greece; (A.V.); (L.C.)
- Clinical, Experimental Surgery & Translational Research, Biomedical Research Foundation (BRFAA), Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece;
| | - Anastasios Gaitanis
- Clinical, Experimental Surgery & Translational Research, Biomedical Research Foundation (BRFAA), Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece;
| | - Nicholas E. Protonotarios
- Mathematics Research Center, Academy of Athens, 11527 Athens, Greece;
- Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, National Center for Scientific Research “Demokritos”, 15341 Athens, Greece
| | - George A. Kastis
- Mathematics Research Center, Academy of Athens, 11527 Athens, Greece;
- Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, National Center for Scientific Research “Demokritos”, 15341 Athens, Greece
| | - Lena Costaridou
- Department of Medical Physics, School of Medicine, University of Patras, 26504 Patras, Greece; (A.V.); (L.C.)
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Boyle AJ, Lindberg A, Tong J, Zhai D, Liu F, Vasdev N. Preliminary PET imaging of [ 11C]evobrutinib in mouse models of colorectal cancer, SARS-CoV-2, and lung damage: Radiosynthesis via base-aided palladium-NiXantphos-mediated 11C-carbonylation. J Labelled Comp Radiopharm 2024; 67:235-244. [PMID: 37691152 DOI: 10.1002/jlcr.4062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/25/2023] [Accepted: 08/24/2023] [Indexed: 09/12/2023]
Abstract
Evobrutinib is a second-generation, highly selective, irreversible Bruton's tyrosine kinase (BTK) inhibitor that has shown efficacy in the autoimmune diseases arthritis and multiple sclerosis. Its development as a positron emission tomography (PET) radiotracer has potential for in vivo imaging of BTK in various disease models including several cancers, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), and lipopolysaccharide (LPS)-induced lung damage. Herein, we report the automated radiosynthesis of [11C]evobrutinib using a base-aided palladium-NiXantphos-mediated 11C-carbonylation reaction. [11C]Evobrutinib was reliably formulated in radiochemical yields of 5.5 ± 1.5% and a molar activity of 34.5 ± 17.3 GBq/μmol (n = 12) with 99% radiochemical purity. Ex vivo autoradiography studies showed high specific binding of [11C]evobrutinib in HT-29 colorectal cancer mouse xenograft tissues (51.1 ± 7.1%). However, in vivo PET/computed tomography (CT) imaging with [11C]evobrutinib showed minimal visualization of HT-29 colorectal cancer xenografts and only a slight increase in radioactivity accumulation in the associated time-activity curves. In preliminary PET/CT studies, [11C]evobrutinib failed to visualize either SARS-CoV-2 pseudovirus infection or LPS-induced injury in mouse models. In conclusion, [11C]evobrutinib was successfully synthesized by 11C-carbonylation and based on our preliminary studies does not appear to be a promising BTK-targeted PET radiotracer in the rodent disease models studied herein.
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Affiliation(s)
- Amanda J Boyle
- Azrieli Centre for Neuro-Radiochemistry, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Anton Lindberg
- Azrieli Centre for Neuro-Radiochemistry, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, Ontario, Canada
| | - Junchao Tong
- Azrieli Centre for Neuro-Radiochemistry, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, Ontario, Canada
| | - Dongxu Zhai
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, Ontario, Canada
| | - Fang Liu
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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Hashimoto F, Onishi Y, Ote K, Tashima H, Reader AJ, Yamaya T. Deep learning-based PET image denoising and reconstruction: a review. Radiol Phys Technol 2024; 17:24-46. [PMID: 38319563 PMCID: PMC10902118 DOI: 10.1007/s12194-024-00780-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/03/2024] [Accepted: 01/04/2024] [Indexed: 02/07/2024]
Abstract
This review focuses on positron emission tomography (PET) imaging algorithms and traces the evolution of PET image reconstruction methods. First, we provide an overview of conventional PET image reconstruction methods from filtered backprojection through to recent iterative PET image reconstruction algorithms, and then review deep learning methods for PET data up to the latest innovations within three main categories. The first category involves post-processing methods for PET image denoising. The second category comprises direct image reconstruction methods that learn mappings from sinograms to the reconstructed images in an end-to-end manner. The third category comprises iterative reconstruction methods that combine conventional iterative image reconstruction with neural-network enhancement. We discuss future perspectives on PET imaging and deep learning technology.
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Affiliation(s)
- Fumio Hashimoto
- Central Research Laboratory, Hamamatsu Photonics K. K, 5000 Hirakuchi, Hamana-Ku, Hamamatsu, 434-8601, Japan.
- Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-Ku, Chiba, 263-8522, Japan.
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba, 263-8555, Japan.
| | - Yuya Onishi
- Central Research Laboratory, Hamamatsu Photonics K. K, 5000 Hirakuchi, Hamana-Ku, Hamamatsu, 434-8601, Japan
| | - Kibo Ote
- Central Research Laboratory, Hamamatsu Photonics K. K, 5000 Hirakuchi, Hamana-Ku, Hamamatsu, 434-8601, Japan
| | - Hideaki Tashima
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba, 263-8555, Japan
| | - Andrew J Reader
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Taiga Yamaya
- Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-Ku, Chiba, 263-8522, Japan
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba, 263-8555, Japan
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5
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Li G, Ma W, Li X, Yang W, Quan Z, Ma T, Wang J, Wang Y, Kang F, Wang J. Performance Evaluation of the uMI Panorama PET/CT System in Accordance with the National Electrical Manufacturers Association NU 2-2018 Standard. J Nucl Med 2024:jnumed.123.265929. [PMID: 38388513 DOI: 10.2967/jnumed.123.265929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 01/11/2024] [Indexed: 02/24/2024] Open
Abstract
The uMI Panorama is a novel PET/CT system using silicon photomultiplier and application-specific integrated circuit technologies and providing exceptional spatial and time-of-flight (TOF) resolutions. The objective of this study was to assess the physical performance of the uMI Panorama in accordance with the National Electrical Manufacturers Association (NEMA) NU 2-2018 standard. Methods: Spatial resolution, sensitivity, count rate performance, accuracy, image quality, and TOF resolution were evaluated in accordance with the guidelines outlined in the NEMA NU 2-2018 standard. Energy resolution was determined using the same dataset acquired for the count rate performance evaluation. Images from a Hoffman brain phantom, a mini-Derenzo phantom, and 3 patient studies were evaluated to demonstrate system performance. Results: The transaxial spatial resolution at full width at half maximum was measured as 2.88 mm with a 1-cm offset from the center axial field of view. The sensitivity at the center axial field of view was 20.1 kcps/MBq. At an activity concentration of 73.0 kBq/mL, the peak noise-equivalent count rate (NECR) reached 576 kcps with a scatter fraction of approximately 33.2%. For activity concentrations at or below the peak NECR, the maximum relative count rate error among all slices remained consistently below 3%. When assessed using the NEMA image quality phantom, overall image contrast recovery ranged from 63.2% to 88.4%, whereas background variability ranged from 4.2% to 1.1%. TOF resolution was 189 ps at 5.3 kBq/mL and was consistently lower than 200 ps for activity concentrations at or below the peak NECR. The patient studies demonstrated that scans at 2 min/bed produced images characterized by low noise and high contrast. Clear delineation of nuclei, spinal cords, and other substructures of the brain was observed in the brain PET images. Conclusion: uMI Panorama, the world's first commercial PET system with sub-200-ps TOF resolution, demonstrated fine spatial and fast TOF resolutions, robust count rate performance, and high quantification accuracy across a wide range of activity levels. This advanced technology offers enhanced diagnostic capability for detecting small and low-contrast lesions while showing promising potential under high-count-rate imaging scenarios.
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Affiliation(s)
- Guiyu Li
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Wenhui Ma
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Xiang Li
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Weidong Yang
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Zhiyong Quan
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Taoqi Ma
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Junling Wang
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yunya Wang
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Fei Kang
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Jing Wang
- Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China
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Tsuda K, Suzuki T, Toya K, Sato E, Fujii H. 3D-OSEM versus FORE + OSEM: Optimal Reconstruction Algorithm for FDG PET with a Short Acquisition Time. World J Nucl Med 2023; 22:234-243. [PMID: 37854086 PMCID: PMC10581748 DOI: 10.1055/s-0043-1774418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023] Open
Abstract
Objective In this study, we investigated the optimal reconstruction algorithm in fluorodeoxyglucose (FDG) positron emission tomography (PET) with a short acquisition time. Materials and Methods In the phantom study, six spheres filled with FDG solution (sphere size: 6.23-37 mm; radioactivity ratio of spheres to background = 8:1) and placed in a National Electrical Manufacturers Association phantom were evaluated. Image acquisition time was 15 to 180 seconds, and the obtained image data were reconstructed using each of the Fourier rebinning (FORE) + ordered subsets expectation-maximization (OSEM) and 3D-OSEM algorithms. In the clinical study, mid-abdominal images of 19 patients were evaluated using regions of interest placed on areas of low, intermediate, and high radioactivity. All obtained images were investigated visually, and quantitatively using maximum standardized uptake value (SUV) and coefficient of variation (CV). Results In the phantom study, FORE + OSEM images with a short acquisition time had large CVs (poor image quality) but comparatively constant maximum SUVs. 3D-OSEM images showed comparatively constant CVs (good image quality) but significantly low maximum SUVs. The results of visual evaluation were well correlated with those of quantitative evaluation. Small spheres were obscured on 3D-OSEM images with short acquisition time, but image quality was not greatly deteriorated. The clinical and phantom studies yielded similar results. Conclusion FDG PET images with a short acquisition time reconstructed by FORE + OSEM showed poorer image quality than by 3D-OSEM. However, images obtained with a short acquisition time and reconstructed with FORE + OSEM showed clearer FDG uptake and more useful than 3D-OSEM in the light of the detection of lesions.
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Affiliation(s)
- Keisuke Tsuda
- Department of Radiological Technology, Faculty of Health Science, Juntendo University, Tokyo, Japan
- Division of Functional Imaging, Exploratory Oncology Research and Clinical Trial Center (EPOC), National Cancer Center, Japan
| | - Takayuki Suzuki
- Division of Functional Imaging, Exploratory Oncology Research and Clinical Trial Center (EPOC), National Cancer Center, Japan
- Department of Radiology, Tohto Clinic, Tokyo, Japan
| | - Kazuhito Toya
- Department of Radiology, International University of Health and Welfare Mita Hospital, Tokyo, Japan
| | - Eisuke Sato
- Department of Radiological Technology, Faculty of Health Science, Juntendo University, Tokyo, Japan
| | - Hirofumi Fujii
- Division of Functional Imaging, Exploratory Oncology Research and Clinical Trial Center (EPOC), National Cancer Center, Japan
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Su P, Yan S, Yang J, Tong J, Samsom J, You F, Li Y, Chen Q, Jiang A, Zhai D, Chen J, Sun Z, Zhou J, Liu M, Lee FJS, Xu ZQD, Wang X, Vasdev N, Wong AHC, Liu F. Serum amyloid P component (SAP) modulates antidepressant effects through promoting membrane insertion of the serotonin transporter. Neuropsychopharmacology 2023; 48:508-517. [PMID: 36076020 PMCID: PMC9852251 DOI: 10.1038/s41386-022-01449-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 08/24/2022] [Accepted: 08/29/2022] [Indexed: 02/02/2023]
Abstract
Serum amyloid P component (SAP) is a universal constituent of human amyloid deposits including those in Alzheimer's disease. SAP has been observed to be elevated in patients with depression, and higher SAP levels are associated with better response to the antidepressant escitalopram. The mechanisms underlying these clinical observations remain unclear. We examined the effect of SAP on serotonin transporter (SERT) expression and localization using Western blot, confocal microscopy, and positron emission tomography with the radioligand [11C]DASB. We also investigated the effect of SAP on treatment response to escitalopram in mice with the forced swim test (FST), a classical behaviour paradigm to assess antidepressant effects. SAP reduced [11C]DASB binding as an index of SERT levels, consistent with Western blots showing decreased total SAP protein because of increased protein degradation. In conjunction with the global decrease in SERT levels, SAP also promotes VAMP-2 mediated SERT membrane insertion. SAP levels are correlated with behavioural despair and SSRI treatment response in mice with FST. In MDD patients, the SAP and membrane SERT levels are correlated with response to SSRI treatment. SAP has complex effects on SERT levels and localization, thereby modulating the effect of SSRIs, which could partially explain clinical variability in antidepressant treatment response. These results add to our understanding of the mechanism for antidepressant drug action, and with further work could be of clinical utility.
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Affiliation(s)
- Ping Su
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China, Beijing, China
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Shuxin Yan
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China, Beijing, China
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Jian Yang
- Beijing AnDing Hospital, Capital Medical University, Beijing, China, Beijing, China
| | - Junchao Tong
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - James Samsom
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Fan You
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China, Beijing, China
| | - Yun Li
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China, Beijing, China
| | - Qiuyue Chen
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China, Beijing, China
| | - Anlong Jiang
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Dongxu Zhai
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Jiahao Chen
- Departments of Neurobiology and Pathology, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing, 100069, China
| | - Zuoli Sun
- Beijing AnDing Hospital, Capital Medical University, Beijing, China, Beijing, China
| | - Jingjing Zhou
- Beijing AnDing Hospital, Capital Medical University, Beijing, China, Beijing, China
| | - Min Liu
- Beijing AnDing Hospital, Capital Medical University, Beijing, China, Beijing, China
| | - Frank J S Lee
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Zhi-Qing David Xu
- Departments of Neurobiology and Pathology, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing, 100069, China
| | - Xin Wang
- Department of Hematology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250021, China
| | - Neil Vasdev
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Departments of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Albert H C Wong
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Departments of Psychiatry, University of Toronto, Toronto, ON, Canada
- Departments of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Fang Liu
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China, Beijing, China.
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Departments of Psychiatry, University of Toronto, Toronto, ON, Canada.
- Departments of Physiology, University of Toronto, Toronto, ON, Canada.
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
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8
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Boyle AJ, Murrell E, Tong J, Schifani C, Narvaez A, Wuest M, West F, Wuest F, Vasdev N. PET Imaging of Fructose Metabolism in a Rodent Model of Neuroinflammation with 6-[ 18F]fluoro-6-deoxy-D-fructose. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238529. [PMID: 36500626 PMCID: PMC9736258 DOI: 10.3390/molecules27238529] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Fluorine-18 labeled 6-fluoro-6-deoxy-D-fructose (6-[18F]FDF) targets the fructose-preferred facilitative hexose transporter GLUT5, which is expressed predominantly in brain microglia and activated in response to inflammatory stimuli. We hypothesize that 6-[18F]FDF will specifically image microglia following neuroinflammatory insult. 6-[18F]FDF and, for comparison, [18F]FDG were evaluated in unilateral intra-striatal lipopolysaccharide (LPS)-injected male and female rats (50 µg/animal) by longitudinal dynamic PET imaging in vivo. In LPS-injected rats, increased accumulation of 6-[18F]FDF was observed at 48 h post-LPS injection, with plateaued uptake (60-120 min) that was significantly higher in the ipsilateral vs. contralateral striatum (0.985 ± 0.047 and 0.819 ± 0.033 SUV, respectively; p = 0.002, n = 4M/3F). The ipsilateral-contralateral difference in striatal 6-[18F]FDF uptake expressed as binding potential (BPSRTM) peaked at 48 h (0.19 ± 0.11) and was significantly decreased at one and two weeks. In contrast, increased [18F]FDG uptake in the ipsilateral striatum was highest at one week post-LPS injection (BPSRTM = 0.25 ± 0.06, n = 4M). Iba-1 and GFAP immunohistochemistry confirmed LPS-induced activation of microglia and astrocytes, respectively, in ipsilateral striatum. This proof-of-concept study revealed an early response of 6-[18F]FDF to neuroinflammatory stimuli in rat brain. 6-[18F]FDF represents a potential PET radiotracer for imaging microglial GLUT5 density in brain with applications in neuroinflammatory and neurodegenerative diseases.
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Affiliation(s)
- Amanda J. Boyle
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON M5T 1R8, Canada
- Correspondence: (A.J.B.); (N.V.); Tel.: +1-416-535-8501 (ext. 30884) (A.J.B.); +1-416-535-8501 (ext. 30988) (N.V.)
| | - Emily Murrell
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Junchao Tong
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Christin Schifani
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Andrea Narvaez
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Melinda Wuest
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2N4, Canada
| | - Frederick West
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2N4, Canada
- Department of Oncology, University of Alberta, Edmonton, AB T6G 1Z2, Canada
| | - Frank Wuest
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2N4, Canada
- Department of Oncology, University of Alberta, Edmonton, AB T6G 1Z2, Canada
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON M5T 1R8, Canada
- Correspondence: (A.J.B.); (N.V.); Tel.: +1-416-535-8501 (ext. 30884) (A.J.B.); +1-416-535-8501 (ext. 30988) (N.V.)
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9
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Khateri P, Lustermann W, Ritzer C, Tsoumpas C, Dissertori G. NEMA characterization of the SAFIR prototype PET insert. EJNMMI Phys 2022; 9:42. [PMID: 35695989 PMCID: PMC9192892 DOI: 10.1186/s40658-022-00454-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 03/28/2022] [Indexed: 11/29/2022] Open
Abstract
Background The SAFIR prototype insert is a preclinical Positron Emission Tomography (PET) scanner built to acquire dynamic images simultaneously with a 7 T Bruker Magnetic Resonance Imaging (MRI) scanner. The insert is designed to perform with an excellent coincidence resolving time of 194 ps Full Width Half Maximum (FWHM) and an energy resolution of 13.8% FWHM. These properties enable it to acquire precise quantitative images at activities as high as 500 MBq suitable for studying fast biological processes within short time frames (< 5 s). In this study, the performance of the SAFIR prototype insert is evaluated according to the NEMA NU 4-2008 standard while the insert is inside the MRI without acquiring MRI data. Results Applying an energy window of 391–601 keV and a coincidence time window of 500 ps the following results are achieved. The average spatial resolution at 5 mm radial offset is 2.6 mm FWHM when using the Filtered Backprojection 3D Reprojection (FBP3DRP) reconstruction method, improving to 1.2 mm when using the Maximum Likelihood Expectation Maximization (MLEM) method. The peak sensitivity at the center of the scanner is 1.06%. The Noise Equivalent count Rate (NECR) is 799 kcps at the highest measured activity of 537 MBq for the mouse phantom and 121 kcps at the highest measured activity of 624 MBq for the rat phantom. The NECR peak is not yet reached for any of the measurements. The scatter fractions are 10.9% and 17.8% for the mouse and rat phantoms, respectively. The uniform region of the image quality phantom has a 3.0% STD, with a 4.6% deviation from the expected number of counts per voxel. The spill-over ratios for the water and air chambers are 0.18 and 0.17, respectively. Conclusions The results satisfy all the requirements initially considered for the insert, proving that the SAFIR prototype insert can obtain dynamic images of small rodents at high activities (\documentclass[12pt]{minimal}
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\begin{document}$$\sim$$\end{document}∼ 500 MBq) with a high sensitivity and an excellent count-rate performance.
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Affiliation(s)
- Parisa Khateri
- Institute for Particle Physics and Astrophysics, ETH Zürich, Zürich, Switzerland.
| | - Werner Lustermann
- Institute for Particle Physics and Astrophysics, ETH Zürich, Zürich, Switzerland
| | - Christian Ritzer
- Institute for Particle Physics and Astrophysics, ETH Zürich, Zürich, Switzerland
| | - Charalampos Tsoumpas
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, Groningen, The Netherlands
| | - Günther Dissertori
- Institute for Particle Physics and Astrophysics, ETH Zürich, Zürich, Switzerland
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10
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Bailly P, Bouzerar R, Galan R, Meyer ME. Phantom study of an in-house amplitude-gating respiratory method with silicon photomultiplier technology positron emission tomography/computed tomography. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106907. [PMID: 35660941 DOI: 10.1016/j.cmpb.2022.106907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 05/23/2022] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
PURPOSE The objective of this phantom study was to determine whether breathing-synchronized, silicon photomultiplier (SiPM)-based PET/CT has a suitable acquisition time for routine clinical use. METHODS Acquisitions were performed in list mode on a 4-ring SiPM-based PET/CT system. The experimental setup consisted of an external respiratory tracking device placed on a commercial dynamic thorax phantom containing a sphere filled with [F-18]-fluorodeoxyglucose. Three-dimensional sinusoidal motion was imposed on the sphere. Data were processed using frequency binning and amplitude binning (the "DMI" and "OFFLINE" methods, respectively). PET sinograms were reconstructed with a Bayesian penalized likelihood algorithm. RESULTS Respiratory gating from a 150‑sec acquisition was successful. The DMI and OFFLINE methods gave similar activity profiles but both were slightly shifted in space; the latter profile was closest to the reference acquisition. CONCLUSION With SiPM PET/CT systems, the amplitude-based processing of breathing-synchronized data is likely to be feasible in routine clinical practice.
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Affiliation(s)
- Pascal Bailly
- Nuclear Medicine Department, Amiens University Medical Center, Amiens, France; Department of Nuclear Medicine, Amiens University Hospital, Amiens, France.
| | - Roger Bouzerar
- Nuclear Medicine Department, Amiens University Medical Center, Amiens, France; Department of Nuclear Medicine, Amiens University Hospital, Amiens, France
| | - Romain Galan
- Nuclear Medicine Department, Amiens University Medical Center, Amiens, France; Jules Verne University of Picardie, Amiens, France; Department of Nuclear Medicine, Amiens University Hospital, Amiens, France
| | - Marc-Etienne Meyer
- Nuclear Medicine Department, Amiens University Medical Center, Amiens, France; Jules Verne University of Picardie, Amiens, France; Department of Nuclear Medicine, Amiens University Hospital, Amiens, France
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11
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Vrachliotis A, Kastis GA, Protonotarios NE, Fokas AS, Nekolla SG, Anagnostopoulos CD, Costaridou L, Gaitanis A. Evaluation of the spline reconstruction technique for preclinical PET imaging. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 217:106668. [PMID: 35176596 DOI: 10.1016/j.cmpb.2022.106668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 12/27/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND AND OBJECTIVE The Spline Reconstruction Technique (SRT) is a fast algorithm based on a novel numerical implementation of an analytic representation of the inverse Radon transform. The purpose of this study is to provide a comparison between SRT, Filtered Back-Projection (FBP), Ordered Subset Expectation Maximization 2D (2D-OSEM), and the Tera-Tomo 3D algorithm, using phantom data at various acquisition durations as well as small-animal data obtained from the Mediso nanoScan® PET/CT scanner. METHODS For this purpose, the "NEMA NU 4-2008 standards" protocol was employed at five different realizations and acquisition durations. In addition to the image quality metrics described by the NEMA protocol, Cold Region Contrast was also considered as a figure-of-merit. Furthermore, Cold Region Contrast was measured in the myocardial infarction region of six male Wistar rats. The volumetric defect quantification was assessed with dedicated computer software. Lastly, plots of Recovery Coefficient and Spill-Over Ratio as a function of the Percentage Standard Deviation were generated, after smoothing the phantom reconstructions with four different Gaussian filters. Statistical significance was determined by employing the Kruskal-Wallis test or One-way Analysis of Variance depending on the normality of the variable's distribution. RESULTS The present study revealed that, at the expense of slightly increased noise in the reconstructed images, SRT resulted in higher Recovery Coefficient values for small hot regions of interest, when compared with FBP and 2D-OSEM at all acquisition durations. Furthermore, SRT reconstructed images exhibit higher Recovery Coefficient values, for all hot regions of interest, when compared to the other 2D algorithms at short acquisition durations. In both phantom and animal studies, SRT achieved a significant improvement over 2D-OSEM for the Spill-Over Ratio and the Cold Region Contrast. These advantages were maintained even after comparing the algorithms at equal noise levels. The Tera-Tomo 3D algorithm (4 subsets, iterations≥ 13) performed significantly better compared to the other algorithms for all figures-of-merit. No statistically significant differences regarding the myocardial defect size were observed between the algorithms investigated. CONCLUSIONS Overall, SRT appears that could be useful for the quantification of small hot regions of interest, cold regions of interest, as well as in low-count imaging applications.
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Affiliation(s)
- Alexandros Vrachliotis
- Department of Medical Physics, School of Medicine, University of Patras, Patras 26504, Greece; Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation, Academy of Athens (BRFAA), Athens 11527, Greece
| | - George A Kastis
- Mathematics Research Center, Academy of Athens, Athens 11527, Greece; Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, National Center for Scientific Research "Demokritos", 15341 Athens, Greece
| | - Nicholas E Protonotarios
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB30WA, United Kingdom
| | - Athanasios S Fokas
- Mathematics Research Center, Academy of Athens, Athens 11527, Greece; Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB30WA, United Kingdom
| | - Stephan G Nekolla
- Klinikum rechts der Isar, Department of Nuclear Medicine and DZHK (German Centre for Cardiovascular Research), Technical University Munich, Partner Site Munich Heart Alliance, Munich 80336, Germany
| | - Constantinos D Anagnostopoulos
- Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation, Academy of Athens (BRFAA), Athens 11527, Greece
| | - Lena Costaridou
- Department of Medical Physics, School of Medicine, University of Patras, Patras 26504, Greece
| | - Anastasios Gaitanis
- Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation, Academy of Athens (BRFAA), Athens 11527, Greece.
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12
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Miller K. A backprojection kernel (KRNL3D) for very-wide-aperture 3D tomography applied to PET with Multigrid for precise use of time-of-flight data. Phys Med Biol 2021; 66. [PMID: 34673567 DOI: 10.1088/1361-6560/ac320a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 10/21/2021] [Indexed: 11/11/2022]
Abstract
In 'KRNL3D' we derive a kernel functionK(y1,y2,φ) whose backprojections from all directions (θ,φ) in the spherical band∣φ∣<φ¯maxon the celestial sphere, when integrated with respect to solid angle, yieldρ, the 3D Gaussian point response function (PRF) of radius 1. ThisK, when convolved against line integral data from an unknown density functionf, yields an integral formula for the 'mollification'ff=ρ∗f, which is a slightly blurred version off, and which stabilizes the mild ill-posedness. Applied to positron emission tomography that backprojection reconstruction occurs stochastically and one emission event at a time, after needed data corrections. We describe Octave (≈Matlab) codes to tabulateKand to test its use with a large apertureφ¯max=π/3orπ/6. 'KRNL3D-TOF' truncates backprojection to a cylindrical patch about the TOF approximate location of each event. These 'backplacements' decrease the computational cost and limit noise and streaking in one region from contaminating the reconstruction in more distant regions. They also retain the ability to count emission events in an isolated blob despiteverylow event counts, a valuable feature fordynamicstudies of metabolic processes. 'Multigrid' allows further reduction in the radius and lengths of the cylinders, thereby enabling even moreprecise use of the TOF information. This precision should be especially important as researchers decrease the TOF uncertainty in newer generation scanners. Finally, we discuss 'further work' that needs to be done. Our codes are being made freely available athttps://github.com/keithmillerberkeley/PET-codes.
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Affiliation(s)
- Keith Miller
- Department of Mathematics, University of California at Berkeley, Berkeley, CA 94720-3840, United States of America
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13
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Tashima H, Yoshida E, Iwao Y, Wakizaka H, Mohammadi A, Nitta M, Kitagawa A, Inaniwa T, Nishikido F, Tsuji AB, Nagai Y, Seki C, Minamimoto T, Fujibayashi Y, Yamaya T. Development of a Multiuse Human-Scale Single-Ring OpenPET System. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2021. [DOI: 10.1109/trpms.2020.3037055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Lobos RA, Ghani MU, Karl WC, Leahy RM, Haldar JP. Autoregression and Structured Low-Rank Modeling of Sinogram Neighborhoods. IEEE TRANSACTIONS ON COMPUTATIONAL IMAGING 2021; 7:1044-1054. [PMID: 35059472 PMCID: PMC8769528 DOI: 10.1109/tci.2021.3114994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Sinograms are commonly used to represent the raw data from tomographic imaging experiments. Although it is already well-known that sinograms posess some amount of redundancy, in this work, we present novel theory suggesting that sinograms will often possess substantial additional redundancies that have not been explicitly exploited by previous methods. Specifically, we derive that sinograms will often satisfy multiple simple data-dependent autoregression relationships. This kind of autoregressive structure enables missing/degraded sinogram samples to be linearly predicted using a simple shift-invariant linear combination of neighboring samples. Our theory also further implies that if sinogram samples are assembled into a structured Hankel/Toeplitz matrix, then the matrix will be expected to have low-rank characteristics. As a result, sinogram restoration problems can be formulated as structured low-rank matrix recovery problems. Illustrations of this approach are provided using several different (real and simulated) X-ray imaging datasets, including comparisons against a state-of-the-art deep learning approach. Results suggest that structured low-rank matrix methods for sinogram recovery can have comparable performance to state-of-the-art approaches. Although our evaluation focuses on competitive comparisons against other approaches, we believe that autoregressive constraints are actually complementary to existing approaches with strong potential synergies.
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Affiliation(s)
- Rodrigo A Lobos
- Signal and Image Processing Institute, Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA 90089 USA
| | - Muhammad Usman Ghani
- Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 USA
| | - W Clem Karl
- Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 USA
| | - Richard M Leahy
- Signal and Image Processing Institute, Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA 90089 USA
| | - Justin P Haldar
- Signal and Image Processing Institute, Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA 90089 USA
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15
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Liu Q, Li C, Liu J, Krish K, Fu X, Zhao J, Chen JC. Technical Note: Performance evaluation of a small-animal PET/CT system based on NEMA NU 4-2008 standards. Med Phys 2021; 48:5272-5282. [PMID: 34252215 DOI: 10.1002/mp.15088] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 04/01/2021] [Accepted: 06/22/2021] [Indexed: 11/06/2022] Open
Abstract
PURPOSE The MetisTM PET/CT is a self-developed, silicon photomultiplier (SiPM) detector-based, rodent PET/CT system. The objective of this study was to evaluate the performance of the system using the National Electrical Manufacturers Association (NEMA) NU 4-2008 standard protocol. METHODS Energy resolution, spatial resolution, sensitivity, scatter fraction (SF), noise-equivalent count rate (NECR), and image quality (IQ) characteristics were measured. A micro Derenzo phantom experiment was performed to evaluate the spatial resolution using three-dimensional ordered-subsets expectation maximization (3D-OSEM) and maximum likelihood expectation maximization (MLEM) reconstructed images. In addition, the CT imaging agent Ioverol 350 was mixed with fluorine-18 (18 F)-fluorodeoxyglucose (FDG) and then injected into the micro Derenzo phantom to evaluate the PET/CT imaging. In vivo PET/CT imaging studies were also conducted in a healthy mouse and rat using 18 F-FDG. RESULTS The mean energy resolution of the system was 15.3%. The tangential resolution was 0.82 mm full-width half-maximum (FWHM) at the center of the field of the view (FOV), and the radial and axial resolution were generally lower than 2.0 mm FWHM. The spatial resolution was significantly improved when using 3D-OSEM, especially the axial FWHM could be improved by up to about 57%. The system absolute sensitivity was 7.7% and 6.8% for an energy window of 200-750 and 350-750 keV respectively. The scatter fraction was 8.2% and 12.1% for the mouse- and rat-like phantom respectively. The peak NECR was 1343.72 kcps at 69 MBq and 640.32 kcps at 53 MBq for the mouse- and rat-like phantom respectively. The 1-mm fillable rod in the IQ phantom can be clearly observed. We can identify the 0.6-mm aperture of the micro Derenzo phantom image clearly using 3D-OSEM (10 subsets, 5 iterations). We also performed the fusion of the PET and CT images of the mouse and the brain imaging of the rat. CONCLUSIONS The results show that the system has the characteristics of high-resolution, high-sensitivity, and excellent IQ and is suitable for rodent imaging-based research.
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Affiliation(s)
- Qiong Liu
- School of Medical Imaging, Xuzhou Medical University, Jiangsu, China
| | - Chaofan Li
- School of Medical Information and Engineering, Xuzhou Medical University, Jiangsu, China
| | - Jiguo Liu
- Shandong Madic Technology Co., Ltd., Shandong, China
| | - Kishore Krish
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Xinlei Fu
- Shandong Madic Technology Co., Ltd., Shandong, China
| | - Jie Zhao
- School of Medical Imaging, Xuzhou Medical University, Jiangsu, China
| | - Jyh-Cheng Chen
- School of Medical Imaging, Xuzhou Medical University, Jiangsu, China.,Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Department of Medical Imaging and Radiological Technology, Yuanpei University of Medical Technology, Hsinchu, Taiwan
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16
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Spencer BA, Berg E, Schmall JP, Omidvari N, Leung EK, Abdelhafez YG, Tang S, Deng Z, Dong Y, Lv Y, Bao J, Liu W, Li H, Jones T, Badawi RD, Cherry SR. Performance Evaluation of the uEXPLORER Total-Body PET/CT Scanner Based on NEMA NU 2-2018 with Additional Tests to Characterize PET Scanners with a Long Axial Field of View. J Nucl Med 2021; 62:861-870. [PMID: 33008932 PMCID: PMC8729871 DOI: 10.2967/jnumed.120.250597] [Citation(s) in RCA: 161] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/21/2020] [Indexed: 01/07/2023] Open
Abstract
The world's first total-body PET scanner with an axial field of view (AFOV) of 194 cm is now in clinical and research use at our institution. The uEXPLORER PET/CT system is the first commercially available total-body PET scanner. Here we present a detailed physical characterization of this scanner based on National Electrical Manufacturers Association (NEMA) NU 2-2018 along with a new set of measurements devised to appropriately characterize the total-body AFOV. Methods: Sensitivity, count-rate performance, time-of-flight resolution, spatial resolution, and image quality were evaluated following the NEMA NU 2-2018 protocol. Additional measurements of sensitivity and count-rate capabilities more representative of total-body imaging were performed using extended-geometry phantoms based on the world-average human height (∼165 cm). Lastly, image quality throughout the long AFOV was assessed with the NEMA image quality (IQ) phantom imaged at 5 axial positions and over a range of expected total-body PET imaging conditions (low dose, delayed imaging, short scan duration). Results: Our performance evaluation demonstrated that the scanner provides a very high sensitivity of 174 kcps/MBq, a count-rate performance with a peak noise-equivalent count rate of approximately 2 Mcps for total-body imaging, and good spatial resolution capabilities for human imaging (≤3.0 mm in full width at half maximum near the center of the AFOV). Excellent IQ, excellent contrast recovery, and low noise properties were illustrated across the AFOV in both NEMA IQ phantom evaluations and human imaging examples. Conclusion: In addition to standard NEMA NU 2-2018 characterization, a new set of measurements based on extending NEMA NU 2-2018 phantoms and experiments was devised to characterize the physical performance of the first total-body PET system. The rationale for these extended measurements was evident from differences in sensitivity, count-rate-activity relationships, and noise-equivalent count-rate limits imposed by differences in dead time and randoms fraction between the NEMA NU 2 70-cm phantoms and the more representative total-body imaging phantoms. Overall, the uEXPLORER PET system provides ultra-high sensitivity that supports excellent spatial resolution and IQ throughout the field of view in both phantom and human imaging.
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Affiliation(s)
- Benjamin A. Spencer
- Department of Biomedical Engineering, University of California–Davis, Davis, California,Department of Radiology, University of California–Davis, Davis, California
| | - Eric Berg
- Department of Biomedical Engineering, University of California–Davis, Davis, California
| | | | - Negar Omidvari
- Department of Biomedical Engineering, University of California–Davis, Davis, California
| | - Edwin K. Leung
- Department of Biomedical Engineering, University of California–Davis, Davis, California
| | | | | | - Zilin Deng
- United Imaging Healthcare, Shanghai, China
| | - Yun Dong
- United Imaging Healthcare, Shanghai, China
| | - Yang Lv
- United Imaging Healthcare, Shanghai, China
| | - Jun Bao
- United Imaging Healthcare, Shanghai, China
| | | | - Hongdi Li
- United Imaging Healthcare, Houston, Texas; and
| | - Terry Jones
- Department of Radiology, University of California–Davis, Davis, California
| | - Ramsey D. Badawi
- Department of Biomedical Engineering, University of California–Davis, Davis, California,Department of Radiology, University of California–Davis, Davis, California
| | - Simon R. Cherry
- Department of Biomedical Engineering, University of California–Davis, Davis, California,Department of Radiology, University of California–Davis, Davis, California
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17
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Bertoglio D, Amhaoul H, Goossens J, Ali I, Jonckers E, Bijnens T, Siano M, Wyffels L, Verhaeghe J, Van der Linden A, Staelens S, Dedeurwaerdere S. TSPO PET upregulation predicts epileptic phenotype at disease onset independently from chronic TSPO expression in a rat model of temporal lobe epilepsy. Neuroimage Clin 2021; 31:102701. [PMID: 34090124 PMCID: PMC8182303 DOI: 10.1016/j.nicl.2021.102701] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/10/2021] [Accepted: 05/14/2021] [Indexed: 12/12/2022]
Abstract
Neuroinflammation is a key component of epileptogenesis, the process leading to acquired epilepsy. In recent years, with the development of non-invasive in vivo positron emission tomography (PET) imaging of translocator protein 18 kDa (TSPO), a marker of neuroinflammation, it has become possible to perform longitudinal studies to characterize neuroinflammation at different disease stages in animal models of epileptogenesis. This study aimed to utilize the prognostic capability of TSPO PET imaging at disease onset (2 weeks post-SE) to categorize epileptic rats with distinct seizure burden based on TSPO levels at disease onset and investigate their association to TSPO expression at the chronic epilepsy stage. Controls (n = 14) and kainic acid-induced status epilepticus (KASE) rats (n = 41) were scanned non-invasively with [18F]PBR111 PET imaging measuring TSPO expression. Animals were monitored using video-electroencephalography (vEEG) up to chronic disease (12 weeks post-SE), at which TSPO levels ([3H]PK11195) as well as other post-mortem abnormalities (namely synaptic density ([3H]UCB-J), neuronal loss (NeuN), and neurodegeneration (FjC)) were investigated. By applying multivariate analysis, TSPO PET imaging at disease onset identified three KASE groups with significantly different spontaneous recurrent seizures (SRS) burden (defined as rare SRS, sporadic SRS, and frequent SRS) (p = 0.003). Interestingly, TSPO levels were significantly different when comparing the three KASE groups (p < 0.0001), with the frequent SRS group characterized only by a limited focal TSPO increase at disease onset. On the contrary, TSPO measured during chronic epilepsy was found to be the highest in the frequent SRS group and correlated with seizure burden (r = 0.826, p < 0.0001). Importantly, early and chronic TSPO levels did not correlate (r = -0.05). Finally, significant pathological changes in neuronal loss, synaptic density, and neurodegeneration were found not only when compared to control animals (p < 0.01), but also between the three KASE rat categories in the hippocampus (p < 0.05). Early and chronic TSPO upregulation following epileptogenic insult appear to be driven by two superimposed dynamic processes. The former is associated with epileptogenesis as measured at disease onset, while the latter is related to seizure frequency as quantified during chronic epilepsy.
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Affiliation(s)
- Daniele Bertoglio
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium; Department of Translational Neurosciences, University of Antwerp, Belgium.
| | - Halima Amhaoul
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Joery Goossens
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Idrish Ali
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | | | - Tom Bijnens
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Matteo Siano
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Leonie Wyffels
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium; Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium
| | | | - Steven Staelens
- Department of Translational Neurosciences, University of Antwerp, Belgium
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18
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Kang SK, Lee JS. Anatomy-guided PET reconstruction using l1bowsher prior. Phys Med Biol 2021; 66. [PMID: 33780912 DOI: 10.1088/1361-6560/abf2f7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 03/29/2021] [Indexed: 12/22/2022]
Abstract
Advances in simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) technology have led to an active investigation of the anatomy-guided regularized PET image reconstruction algorithm based on MR images. Among the various priors proposed for anatomy-guided regularized PET image reconstruction, Bowsher's method based on second-order smoothing priors sometimes suffers from over-smoothing of detailed structures. Therefore, in this study, we propose a Bowsher prior based on thel1-norm and an iteratively reweighting scheme to overcome the limitation of the original Bowsher method. In addition, we have derived a closed solution for iterative image reconstruction based on this non-smooth prior. A comparison study between the originall2and proposedl1Bowsher priors was conducted using computer simulation and real human data. In the simulation and real data application, small lesions with abnormal PET uptake were better detected by the proposedl1Bowsher prior methods than the original Bowsher prior. The originall2Bowsher leads to a decreased PET intensity in small lesions when there is no clear separation between the lesions and surrounding tissue in the anatomical prior. However, the proposedl1Bowsher prior methods showed better contrast between the tumors and surrounding tissues owing to the intrinsic edge-preserving property of the prior which is attributed to the sparseness induced byl1-norm, especially in the iterative reweighting scheme. Besides, the proposed methods demonstrated lower bias and less hyper-parameter dependency on PET intensity estimation in the regions with matched anatomical boundaries in PET and MRI. Therefore, these methods will be useful for improving the PET image quality based on the anatomical side information.
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Affiliation(s)
- Seung Kwan Kang
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea.,Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.,Brightonix Imaging Inc., Seoul 04793, Republic of Korea
| | - Jae Sung Lee
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea.,Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.,Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.,Brightonix Imaging Inc., Seoul 04793, Republic of Korea
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19
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Behnamian H, Yousefnejad S, Shafiee M, Rafiei A. Study of two-layer tapered depth of interaction PET detector. Appl Radiat Isot 2021; 174:109731. [PMID: 33964523 DOI: 10.1016/j.apradiso.2021.109731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 04/05/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
Improving detection efficiency in small animal PET scanners without degrading spatial resolution is one of the main problems of these scanners. Commercial small animal PET scanners use different methods to achieve desirable levels of sensitivity and spatial resolution. GE Healthcare eXplore VISTA PET scanner uses double layer (LYSO-GSO) depth-of-interaction (DOI) capable cuboid detector modules. In this work, the design of GE Healthcare eXplore VISTA PET scanner is improved using tapered detector geometry instead of cuboid geometry. Using tapered detector geometry, the gaps between adjacent modules are filled and the sensitive volume has increased about 11.5%. The new designed PET scanner sensitivity and spatial resolution are studied for different crystal layer configurations (LYSO-GSO and GSO-LYSO with different thicknesses). As expected, average sensitivity over FOV is improved. Spatial resolution is slightly degraded but it is still uniform over FOV.
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Affiliation(s)
- Hadi Behnamian
- Department of Physics, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada.
| | - Sirous Yousefnejad
- Iranian Light Source Facility, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran.
| | - Mehdi Shafiee
- Energetic Cosmos Laboratory, Nazarbayev University, Astana, Kazakhstan.
| | - Alireza Rafiei
- Department of Energy Engineering, Sharif University of Technology, Tehran, Iran.
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Wettenhovi VV, Vauhkonen M, Kolehmainen V. OMEGA-open-source emission tomography software. Phys Med Biol 2021; 66:065010. [PMID: 33588401 DOI: 10.1088/1361-6560/abe65f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this paper we present OMEGA, an open-source software, for efficient and fast image reconstruction in positron emission tomography (PET). OMEGA uses the scripting language of MATLAB and GNU Octave allowing reconstruction of PET data with a MATLAB or GNU Octave interface. The goal of OMEGA is to allow easy and fast reconstruction of any PET data, and to provide a computationally efficient, easy-access platform for development of new PET algorithms with built-in forward and backward projection operations available to the user as a MATLAB/Octave class. OMEGA also includes direct support for GATE simulated data, facilitating easy evaluation of the new algorithms using Monte Carlo simulated PET data. OMEGA supports parallel computing by utilizing OpenMP for CPU implementations and OpenCL for GPU allowing any hardware to be used. OMEGA includes built-in function for the computation of normalization correction and allows several other corrections to be applied such as attenuation, randoms or scatter. OMEGA includes several different maximum-likelihood and maximum a posteriori (MAP) algorithms with several different priors. The user can also input their own priors to the built-in MAP functions. The image reconstruction in OMEGA can be computed either by using an explicitly computed system matrix or with a matrix-free formalism, where the latter can be accelerated with OpenCL. We provide an overview on the software and present some examples utilizing the different features of the software.
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Affiliation(s)
- V-V Wettenhovi
- Department of Applied Physics, University of Eastern Finland, Finland
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21
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Narayanaswami V, Tong J, Schifani C, Bloomfield PM, Dahl K, Vasdev N. Preclinical Evaluation of TSPO and MAO-B PET Radiotracers in an LPS Model of Neuroinflammation. PET Clin 2021; 16:233-247. [PMID: 33648665 DOI: 10.1016/j.cpet.2020.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Discovery of novel PET radiotracers targeting neuroinflammation (microglia and astrocytes) is actively pursued. Employing a lipopolysaccharide (LPS) rat model, this longitudinal study evaluated the translocator protein 18-kDa radiotracer [18F]FEPPA (primarily microglia) and monoamine oxidase B radiotracers [11C]L-deprenyl and [11C]SL25.1188 (astrocytes preferred). Increased [18F]FEPPA binding peaked at 1 week in LPS-injected striatum whereas increased lazabemide-sensitive [11C]L-deprenyl binding developed later. No increase in radiotracer uptake was observed for [11C]SL25.1188. The unilateral intrastriatal LPS rat model may serve as a useful tool for benchmarking PET tracers targeted toward distinct phases of neuroinflammatory reactions involving both microglia and astrocytes.
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Affiliation(s)
- Vidya Narayanaswami
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room 270, Toronto, Ontario M5T 1R8, Canada
| | - Junchao Tong
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room 339, Toronto, Ontario M5T 1R8, Canada
| | - Christin Schifani
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room 270, Toronto, Ontario M5T 1R8, Canada
| | - Peter M Bloomfield
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room B26A, Toronto, Ontario M5T 1R8, Canada
| | - Kenneth Dahl
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room B02, Toronto, Ontario M5T 1R8, Canada
| | - Neil Vasdev
- Department of Psychiatry, Brain Health Imaging Centre, Azrieli Centre for Neuro-Radiochemistry, Centre for Addiction and Mental Health, University of Toronto, 250 College Street, Room PET G2, Toronto, Ontario M5T 1R8, Canada.
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22
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Valli M, Cho SS, Masellis M, Chen R, Koshimori Y, Diez-Cirarda M, Mihaescu A, Christopher L, Strafella AP. Extra-striatal dopamine in Parkinson's disease with rapid eye movement sleep behavior disorder. J Neurosci Res 2021; 99:1177-1187. [PMID: 33470445 DOI: 10.1002/jnr.24779] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 11/05/2022]
Abstract
Rapid eye movement sleep behavior disorder (RBD) is a common condition found in more than 50% of the patients with Parkinson's disease (PD). Molecular imaging shows that PD with RBD (PD-RBD+) have lower striatal dopamine transporter activity within the caudate and putamen relative to PD without RBD (PD-RBD-). However, the characterization of the extra-striatal dopamine within the mesocortical and mesolimbic pathways remains unknown. We aim to elucidate this with PET imaging in 15 PD-RBD+ and 15 PD-RBD- patients, while having 15 age-matched healthy controls (HC). Each participant underwent a single PET scan with [11 C]FLB-457 to detect the D2 receptor availability within the extra-striatal regions of interest (ROI), including the prefrontal, temporal, and limbic areas. [11 C]FLB-457 retention was expressed as the nondisplaceable binding potential. Our results reveal that relative to HC, PD-RBD+ and PD-RBD- patients have lower levels of D2 receptor availability within the uncus parahippocampus, superior, lateral, and inferior temporal cortex. PD-RBD+ showed steep decline in D2 receptors within the left uncus parahippocampus with increasing disease severity, but this was not observed for PD-RBD- patients. Findings imply that extra-striatal dopaminergic system may play a role in contributing to symptomatic progress in PD patients with RBD. However, validation with more advanced PD patients are needed.
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Affiliation(s)
- Mikaeel Valli
- Brain Health Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, ON, Canada.,Krembil Research Institute, University Health Network, University of Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, ON, Canada
| | - Sang Soo Cho
- Brain Health Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, ON, Canada.,Krembil Research Institute, University Health Network, University of Toronto, ON, Canada
| | - Mario Masellis
- Institute of Medical Science, University of Toronto, ON, Canada.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Robert Chen
- Krembil Research Institute, University Health Network, University of Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, ON, Canada.,Morton and Gloria Shulman Movement Disorder Unit & E.J. Safra Parkinson Disease Program, Neurology Division, Department of Medicine, Toronto Western Hospital, UHN, University of Toronto, ON, Canada
| | - Yuko Koshimori
- Brain Health Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, ON, Canada.,Music and Health Research Collaboratory (MaRC), Faculty of Music, University of Toronto, Toronto, ON, Canada
| | - Maria Diez-Cirarda
- Brain Health Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, ON, Canada.,Krembil Research Institute, University Health Network, University of Toronto, ON, Canada.,Neurodegenerative Diseases Group, Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
| | - Alexander Mihaescu
- Brain Health Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, ON, Canada.,Krembil Research Institute, University Health Network, University of Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, ON, Canada
| | - Leigh Christopher
- Brain Health Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, ON, Canada.,Krembil Research Institute, University Health Network, University of Toronto, ON, Canada
| | - Antonio P Strafella
- Brain Health Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, ON, Canada.,Krembil Research Institute, University Health Network, University of Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, ON, Canada.,Morton and Gloria Shulman Movement Disorder Unit & E.J. Safra Parkinson Disease Program, Neurology Division, Department of Medicine, Toronto Western Hospital, UHN, University of Toronto, ON, Canada
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McGinnity CJ, Riaño Barros DA, Hinz R, Myers JF, Yaakub SN, Thyssen C, Heckemann RA, de Tisi J, Duncan JS, Sander JW, Lingford-Hughes A, Koepp MJ, Hammers A. Αlpha 5 subunit-containing GABA A receptors in temporal lobe epilepsy with normal MRI. Brain Commun 2021; 3:fcaa190. [PMID: 33501420 PMCID: PMC7811756 DOI: 10.1093/braincomms/fcaa190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 09/06/2020] [Accepted: 09/24/2020] [Indexed: 01/08/2023] Open
Abstract
GABAA receptors containing the α5 subunit mediate tonic inhibition and are widely expressed in the limbic system. In animals, activation of α5-containing receptors impairs hippocampus-dependent memory. Temporal lobe epilepsy is associated with memory impairments related to neuron loss and other changes. The less selective PET ligand [11C]flumazenil has revealed reductions in GABAA receptors. The hypothesis that α5 subunit receptor alterations are present in temporal lobe epilepsy and could contribute to impaired memory is untested. We compared α5 subunit availability between individuals with temporal lobe epilepsy and normal structural MRI ('MRI-negative') and healthy controls, and interrogated the relationship between α5 subunit availability and episodic memory performance, in a cross-sectional study. Twenty-three healthy male controls (median ± interquartile age 49 ± 13 years) and 11 individuals with MRI-negative temporal lobe epilepsy (seven males; 40 ± 8) had a 90-min PET scan after bolus injection of [11C]Ro15-4513, with arterial blood sampling and metabolite correction. All those with epilepsy and six controls completed the Adult Memory and Information Processing Battery on the scanning day. 'Bandpass' exponential spectral analyses were used to calculate volumes of distribution separately for the fast component [V F; dominated by signal from α1 (α2, α3)-containing receptors] and the slow component (V S; dominated by signal from α5-containing receptors). We made voxel-by-voxel comparisons between: the epilepsy and control groups; each individual case versus the controls. We obtained parametric maps of V F and V S measures from a single bolus injection of [11C]Ro15-4513. The epilepsy group had higher V S in anterior medial and lateral aspects of the temporal lobes, the anterior cingulate gyri, the presumed area tempestas (piriform cortex) and the insulae, in addition to increases of ∼24% and ∼26% in the ipsilateral and contralateral hippocampal areas (P < 0.004). This was associated with reduced V F:V S ratios within the same areas (P < 0.009). Comparisons of V S for each individual with epilepsy versus controls did not consistently lateralize the epileptogenic lobe. Memory scores were significantly lower in the epilepsy group than in controls (mean ± standard deviation -0.4 ± 1.0 versus 0.7 ± 0.3; P = 0.02). In individuals with epilepsy, hippocampal V S did not correlate with memory performance on the Adult Memory and Information Processing Battery. They had reduced V F in the hippocampal area, which was significant ipsilaterally (P = 0.03), as expected from [11C]flumazenil studies. We found increased tonic inhibitory neurotransmission in our cohort of MRI-negative temporal lobe epilepsy who also had co-morbid memory impairments. Our findings are consistent with a subunit shift from α1/2/3 to α5 in MRI-negative temporal lobe epilepsy.
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Affiliation(s)
- Colm J McGinnity
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Daniela A Riaño Barros
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
| | - Rainer Hinz
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester M20 3LJ, UK
| | - James F Myers
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Siti N Yaakub
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Charlotte Thyssen
- Medical Image and Signal Processing (MEDISIP), Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, 9000 Ghent, Belgium
| | - Rolf A Heckemann
- Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Jane de Tisi
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - John S Duncan
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - Josemir W Sander
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede 2103SW, The Netherlands
| | - Anne Lingford-Hughes
- Neuropsychopharmacology Unit, Centre for Psychiatry, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London W12 0NN, UK
| | - Matthias J Koepp
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - Alexander Hammers
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
- Neurodis Foundation, CERMEP, Imagerie du Vivant, 69003 Lyon, France
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Muscle activities during shoulder internal rotation differ in arm position: a preliminary quantitative analysis using positron emission tomography. Skeletal Radiol 2020; 49:1839-1847. [PMID: 32533204 DOI: 10.1007/s00256-020-03490-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To investigate the muscle activity patterns of the glenohumeral joint during internal rotation both with the arm at 0° and 90° of abduction using 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography (PET) and magnetic resonance imaging (MRI). MATERIALS AND METHODS Six healthy male volunteers underwent PET examination after performing active glenohumeral internal rotation exercise using an elastic band both with the arm at 0° and 90° of abduction. As a control, PET scan under resting condition was also performed. The exercise was performed before and after 18 fluorodeoxyglucose injection. Each PET image was fused to the corresponding MRI to identify each muscle. The standardized uptake value (SUV) of each muscle was compared between the two arm positions. RESULTS With the arm at 0° of abduction, the SUV increased significantly after exercise both in the middle and inferior 1/3 of the subscapularis, which were significantly higher than that of the superior 1/3 of the subscapularis (P < 0.05). The SUV of the inferior 1/3 of the subscapularis was significantly higher at 90° of abduction than at 0° of abduction and was significantly higher than that of the superior 1/3 at 90° of abduction (P < 0.01). The SUV after exercise in the inferior infraspinatus and teres minor increased. CONCLUSIONS The middle and inferior parts of the subscapularis are the main shoulder internal rotators in 0° of abduction, whereas the inferior part of the subscapularis is the main internal rotator in 90° of abduction.
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Over-activation of primate subgenual cingulate cortex enhances the cardiovascular, behavioral and neural responses to threat. Nat Commun 2020; 11:5386. [PMID: 33106488 PMCID: PMC7588412 DOI: 10.1038/s41467-020-19167-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/30/2020] [Indexed: 01/10/2023] Open
Abstract
Stress-related disorders such as depression and anxiety are characterized by enhanced negative emotion and physiological dysfunction. Whilst elevated activity within area 25 of the subgenual anterior cingulate cortex (sgACC/25) has been implicated in these illnesses, it is unknown whether this over-activity is causal. By combining targeted intracerebral microinfusions with cardiovascular and behavioral monitoring in marmosets, we show that over-activation of sgACC/25 reduces vagal tone and heart rate variability, alters cortisol dynamics during stress and heightens reactivity to proximal and distal threat. 18F-FDG PET imaging shows these changes are accompanied by altered activity within a network of brain regions including the amygdala, hypothalamus and dorsolateral prefrontal cortex. Ketamine, shown to have rapid antidepressant effects, fails to reverse elevated arousal to distal threat contrary to the beneficial effects we have previously demonstrated on over-activation induced reward blunting, illustrating the symptom-specificity of its actions. Alexander et al. causally implicate over-activity in primate subgenual cingulate in affective and cardiovascular dysfunction relevant to anxiety and depression. Over-activation led to elevated activity in a stress-related network whilst decreasing activity in higher-order prefrontal cognitive regions.
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Boyle AJ, Tong J, Zoghbi SS, Pike VW, Innis RB, Vasdev N. Repurposing 11C-PS13 for PET Imaging of Cyclooxygenase-1 in Ovarian Cancer Xenograft Mouse Models. J Nucl Med 2020; 62:665-668. [DOI: 10.2967/jnumed.120.249367] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 08/17/2020] [Indexed: 11/16/2022] Open
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Brain 18F-FDG PET analysis via interval-valued reconstruction: proof of concept for Alzheimer’s disease diagnosis. Ann Nucl Med 2020; 34:565-574. [DOI: 10.1007/s12149-020-01490-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/31/2020] [Indexed: 10/24/2022]
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Narayanaswami V, Tong J, Fiorino F, Severino B, Sparaco R, Magli E, Giordano F, Bloomfield PM, Prabhakaran J, Mann JJ, Vasdev N, Dahl K, Kumar JSD. Synthesis, in vitro and in vivo evaluation of 11C-O-methylated arylpiperazines as potential serotonin 1A (5-HT 1A) receptor antagonist radiotracers. EJNMMI Radiopharm Chem 2020; 5:13. [PMID: 32430632 PMCID: PMC7237647 DOI: 10.1186/s41181-020-00096-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/23/2020] [Indexed: 01/23/2023] Open
Abstract
Background Serotonin 1A (5-HT1A) receptors are implicated in the pathogenesis of several psychiatric and neurodegenerative disorders motivating the development of suitable radiotracers for in vivo positron emission tomography (PET) neuroimaging. The gold standard PET imaging agent for this target is [carbonyl-11C]WAY-100635, labeled via a technically challenging multi-step reaction that has limited its widespread use. While several antagonist and agonist-based PET radiotracers for 5-HT 1A receptors have been developed, their clinical translation has been hindered by methodological challenges and/or and non-specific binding. As a result, there is continued interest in the development of new and more selective 5-HT1A PET tracers having a relatively easier and reliable radiosynthesis process for routine production and with favorable metabolism to facilitate tracer-kinetic modeling. The purpose of the current study was to develop and characterize a radioligand with suitable characteristics for imaging 5-HT1A receptors in the brain. The current study reports the in vitro characterization and radiosyntheses of three candidate 5-HT1A receptor antagonists, DF-100 (1), DF-300 (2) and DF-400 (3), to explore their suitability as potential PET radiotracers. Results Syntheses of 1–3 and corresponding precursors for radiolabeling were achieved from isonicotinic, picolinic acid or picolino nitrile. In vitro binding studies demonstrated nanomolar affinity of the compounds for 5-HT1A receptors. Binding of 1–3 for other biogenic amines, neurotransmitter receptors, and transporters was negligible with the exception of moderate affinities for α1-adrenergic receptors (4–6-fold less potent than that for 5-HT1A receptor). Radioligands [11C]1–3 were efficiently prepared by 11C-O-methylation of the corresponding phenolic precursor in non-decay corrected radiochemical yields of 7–11% with > 99% chemical and radiochemical purities. Dynamic PET studies in rats demonstrated negligible brain uptake of [11C]1 and [11C]2. In contrast, significant brain uptake of [11C]3 was observed with an early peak SUV of 4–5. However, [11C]3 displayed significant off-target binding attributed to α1-adrenergic receptors based on regional distribution (thalamus>hippocampus) and blocking studies. Conclusion Despite efficient radiolabeling, results from PET imaging experiments limit the application of [11C]3 for in vivo quantification of 5-HT1A receptors. Nevertheless, derivatives of compound 3 may provide a scaffold for alternative PET radiotracers with improved selectivity for 5-HT 1A receptors or α1-adrenergic receptors.
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Affiliation(s)
- Vidya Narayanaswami
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre & Preclinical Imaging, Centre for Addiction and Mental Health, Toronto, Ontario, M5T-1R8, Canada
| | - Junchao Tong
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre & Preclinical Imaging, Centre for Addiction and Mental Health, Toronto, Ontario, M5T-1R8, Canada
| | - Ferdinando Fiorino
- Department of Pharmacy, University of Naples, Via D. Montesano, 49, 8013, Naples, Italy
| | - Beatrice Severino
- Department of Pharmacy, University of Naples, Via D. Montesano, 49, 8013, Naples, Italy
| | - Rosa Sparaco
- Department of Pharmacy, University of Naples, Via D. Montesano, 49, 8013, Naples, Italy
| | - Elisa Magli
- Department of Pharmacy, University of Naples, Via D. Montesano, 49, 8013, Naples, Italy
| | - Flavia Giordano
- Department of Pharmacy, University of Naples, Via D. Montesano, 49, 8013, Naples, Italy
| | - Peter M Bloomfield
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre & Preclinical Imaging, Centre for Addiction and Mental Health, Toronto, Ontario, M5T-1R8, Canada
| | - Jaya Prabhakaran
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, USA
| | - J John Mann
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, USA.,Department of Psychiatry, Columbia University Medical Center, New York, USA
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre & Preclinical Imaging, Centre for Addiction and Mental Health, Toronto, Ontario, M5T-1R8, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T-1R8, Canada
| | - Kenneth Dahl
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre & Preclinical Imaging, Centre for Addiction and Mental Health, Toronto, Ontario, M5T-1R8, Canada.
| | - J S Dileep Kumar
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, USA.
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Salvadori J, Labour J, Odille F, Marie PY, Badel JN, Imbert L, Sarrut D. Monte Carlo simulation of digital photon counting PET. EJNMMI Phys 2020; 7:23. [PMID: 32335787 PMCID: PMC7183520 DOI: 10.1186/s40658-020-00288-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/17/2020] [Indexed: 12/14/2022] Open
Abstract
A GATE Monte Carlo model of the Philips Vereos digital photon counting PET imaging system using silicon photo-multiplier detectors was proposed. It was evaluated against experimental data in accordance with NEMA guidelines. Comparisons were performed using listmode data in order to remain independent of image reconstruction algorithms. An original line of response-based method is proposed to estimate intrinsic spatial resolution without reconstruction. Four sets of experiments were performed: (1) count rates and scatter fraction, (2) energy and timing resolutions, (3) sensitivity, and (4) intrinsic spatial resolution. Experimental and simulated data were found to be in good agreement, with overall differences lower than 10% for activity concentrations used in most standard clinical applications. Illustrative image reconstructions were provided. In conclusion, the proposed Monte Carlo model was validated and can be used for numerous studies such as optimizing acquisition parameters or reconstruction algorithms.
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Affiliation(s)
- Julien Salvadori
- IADI, INSERM UMR 1254, Université de Lorraine, Nancy, France. .,Département de médecine nucléaire et plateforme Nancyclotep, CHRU-Nancy, Université de Lorraine, Nancy, France.
| | - Joey Labour
- CREATIS, Centre Léon Bérard, CNRS UMR 5220, INSERM U 1044, Université de Lyon; INSA-Lyon; Université Lyon 1, Lyon, France
| | - Freddy Odille
- IADI, INSERM UMR 1254, Université de Lorraine, Nancy, France
| | - Pierre-Yves Marie
- Département de médecine nucléaire et plateforme Nancyclotep, CHRU-Nancy, Université de Lorraine, Nancy, France.,DCAC, INSERM UMR 1116, Université de Lorraine, Nancy, France
| | - Jean-Noël Badel
- CREATIS, Centre Léon Bérard, CNRS UMR 5220, INSERM U 1044, Université de Lyon; INSA-Lyon; Université Lyon 1, Lyon, France
| | - Laëtitia Imbert
- IADI, INSERM UMR 1254, Université de Lorraine, Nancy, France.,Département de médecine nucléaire et plateforme Nancyclotep, CHRU-Nancy, Université de Lorraine, Nancy, France
| | - David Sarrut
- CREATIS, Centre Léon Bérard, CNRS UMR 5220, INSERM U 1044, Université de Lyon; INSA-Lyon; Université Lyon 1, Lyon, France
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López-Montes A, Galve P, Udias JM, Cal-González J, Vaquero JJ, Desco M, Herraiz JL. Real-Time 3D PET Image with Pseudoinverse Reconstruction. APPLIED SCIENCES-BASEL 2020. [DOI: https://doi.org/10.3390/app10082829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Real-time positron emission tomography (PET) may provide information from first-shot images, enable PET-guided biopsies, and allow awake animal studies. Fully-3D iterative reconstructions yield the best images in PET, but they are too slow for real-time imaging. Analytical methods such as Fourier back projection (FBP) are very fast, but yield images of poor quality with artifacts due to noise or data incompleteness. In this work, an image reconstruction based on the pseudoinverse of the system response matrix (SRM) is presented. w. To implement the pseudoinverse method, the reconstruction problem is separated into two stages. First, the axial part of the SRM is pseudo-inverted (PINV) to rebin the 3D data into 2D datasets. Then, the resulting 2D slices can be reconstructed with analytical methods or by applying the pseudoinverse algorithm again. The proposed two-step PINV reconstruction yielded good-quality images at a rate of several frames per second, compatible with real time applications. Furthermore, extremely fast direct PINV reconstruction of projections of the 3D image collapsed along specific directions can be implemented.
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Abstract
Real-time positron emission tomography (PET) may provide information from first-shot images, enable PET-guided biopsies, and allow awake animal studies. Fully-3D iterative reconstructions yield the best images in PET, but they are too slow for real-time imaging. Analytical methods such as Fourier back projection (FBP) are very fast, but yield images of poor quality with artifacts due to noise or data incompleteness. In this work, an image reconstruction based on the pseudoinverse of the system response matrix (SRM) is presented. w. To implement the pseudoinverse method, the reconstruction problem is separated into two stages. First, the axial part of the SRM is pseudo-inverted (PINV) to rebin the 3D data into 2D datasets. Then, the resulting 2D slices can be reconstructed with analytical methods or by applying the pseudoinverse algorithm again. The proposed two-step PINV reconstruction yielded good-quality images at a rate of several frames per second, compatible with real time applications. Furthermore, extremely fast direct PINV reconstruction of projections of the 3D image collapsed along specific directions can be implemented.
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Nagachinta S, Becker G, Dammicco S, Serrano ME, Leroi N, Bahri MA, Plenevaux A, Lemaire C, Lopez R, Luxen A, de la Fuente M. Radiolabelling of lipid-based nanocarriers with fluorine-18 for in vivo tracking by PET. Colloids Surf B Biointerfaces 2020; 188:110793. [DOI: 10.1016/j.colsurfb.2020.110793] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/14/2019] [Accepted: 01/10/2020] [Indexed: 12/31/2022]
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Maitra R. Efficient Bandwidth Estimation in 2D Filtered Backprojection Reconstruction. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2019; 28:5610-5619. [PMID: 31180891 PMCID: PMC6992161 DOI: 10.1109/tip.2019.2919428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A generalized cross-validation approach to estimate the reconstruction filter bandwidth in 2D filtered backprojection is presented. The method writes the reconstruction equation in equivalent backprojected filtering form, derives results on eigendecomposition of symmetric 2D circulant matrices, and applies them to make bandwidth estimation a computationally efficient operation within the context of standard backprojected filtering reconstruction. Performance evaluations on a range of simulated emission tomography experiments give promising results. The superior performance holds at both low and high total expected counts, pointing to the method's applicability even in weak signal-to-noise-ratio situations. The approach also applies to the more general class of elliptically symmetric filters, with the reconstructed estimate's performance often better than even that obtained with the true optimal radially symmetric filter.
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Amirrashedi M, Sarkar S, Ghafarian P, Hashemi Shahraki R, Geramifar P, Zaidi H, Ay MR. NEMA NU-4 2008 performance evaluation of Xtrim-PET: A prototype SiPM-based preclinical scanner. Med Phys 2019; 46:4816-4825. [PMID: 31448421 DOI: 10.1002/mp.13785] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/05/2019] [Accepted: 08/06/2019] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Xtrim-PET is a newly designed Silicon Photomultipliers (SiPMs)-based prototype PET scanner dedicated for small laboratory animal imaging. We present the performance evaluation of the Xtrim-PET scanner following NEMA NU-4 2008 standards to help optimizing scanning protocols which can be achieved through standard and reliable system performance characterization. METHODS The performance assessment was conducted according to the National Electrical Manufacturers Association (NEMA) NU-4 2008 standards in terms of spatial resolution, sensitivity, counting rate performance, scatter fraction and image quality. The in vivo imaging capability of the scanner is also showcased through scanning a normal mouse injected with 18 F-FDG. Furthermore, the performance characteristics of the developed scanner are compared with commercially available systems and current prototypes. RESULTS The volumetric spatial resolution at 5 mm radial offset from the central axis of the scanner is 6.81 µl, whereas a peak absolute sensitivity of 2.99% was achieved using a 250-650 keV energy window and a 10 ns timing window. The peak noise-equivalent count rate (NECR) using a mouse-like phantom is 113.18 kcps at 0.34 KBq/cc with 12.5% scatter fraction, whereas the NECR peaked at 82.76 kcps for an activity concentration level of 0.048 KBq/cc with a scatter fraction of 25.8% for rat-like phantom. An excellent uniformity (3.8%) was obtained using NEMA image quality phantom. Recovery coefficients of 90%, 86%, 68%, 40% and 12% were calculated for rod diameters of 5, 4, 3, 2 and 1 mm, respectively. Spill-over ratios for air-filled and water-filled chambers were 35% and 25% without applying any correction for attenuation and Compton scattering effects. CONCLUSION Our findings revealed that beyond compactness, lightweight, easy installation and good energy resolution, the Xtrim-PET prototype presents a reasonable performance making it suitable for preclinical molecular imaging-based research.
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Affiliation(s)
- Mahsa Amirrashedi
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.,Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
| | - Saeed Sarkar
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.,Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
| | - Pardis Ghafarian
- Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.,PET/CT and Cyclotron Center, Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Reza Hashemi Shahraki
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.,Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
| | - Parham Geramifar
- Research Center for Nuclear Medicine, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, CH-1211, Switzerland.,Geneva University Neurocenter, Geneva University, CH-1205, Geneva, Switzerland.,Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, 9700 RB, Groningen, Netherlands.,Department of Nuclear Medicine, University of Southern Denmark, 500, Odense, Denmark
| | - Mohammad Reza Ay
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.,Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
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Insula serotonin 2A receptor binding and gene expression contribute to serotonin transporter polymorphism anxious phenotype in primates. Proc Natl Acad Sci U S A 2019; 116:14761-14768. [PMID: 31266890 PMCID: PMC6642374 DOI: 10.1073/pnas.1902087116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Genetic variation in the serotonin transporter gene (SLC6A4) is associated with vulnerability to affective disorders and pharmacotherapy efficacy. We recently identified sequence polymorphisms in the common marmoset SLC6A4 repeat region (AC/C/G and CT/T/C) associated with individual differences in anxiety-like trait, gene expression, and response to antidepressants. The mechanisms underlying the effects of these polymorphisms are unknown, but a key mediator of serotonin action is the serotonin 2A receptor (5HT2A). Thus, we correlated 5HT2A binding potential (BP) and RNA gene expression in 16 SLC6A4 genotyped marmosets with responsivity to 5HT2A antagonism during the human intruder test of anxiety. Voxel-based analysis and RNA measurements showed a reduction in 5HT2A BP and gene expression specifically in the right posterior insula of individuals homozygous for the anxiety-related variant AC/C/G. These same marmosets displayed an anxiogenic, dose-dependent response to the human intruder after 5HT2A pharmacological antagonism, while CT/T/C individuals showed no effect. A voxel-based correlation analysis, independent of SLC6A4 genotype, revealed that 5HT2A BP in the adjacent right anterior insula and insula proisocortex was negatively correlated with trait anxiety scores. Moreover, 5HT2A BP in both regions was a good predictor of the size and direction of the acute emotional response to the human intruder threat after 5HT2A antagonism. Our findings suggest that genetic variation in the SLC6A4 repeat region may contribute to the trait anxious phenotype via neurochemical changes in brain areas implicated in interoceptive and emotional processing, with a critical role for the right insula 5HT2A in the regulation of affective responses to threat.
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Kucharczak F, Ben Bouallegue F, Strauss O, Mariano-Goulart D. Confidence Interval Constraint-Based Regularization Framework for PET Quantization. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:1513-1523. [PMID: 30561343 DOI: 10.1109/tmi.2018.2886431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this paper, a new generic regularized reconstruction framework based on confidence interval constraints for tomographic reconstruction is presented. As opposed to usual state-of-the-art regularization methods that try to minimize a cost function expressed as the sum of a data-fitting term and a regularization term weighted by a scalar parameter, the proposed algorithm is a two-step process. The first step concentrates on finding a set of images that rely on the direct estimation of confidence intervals for each reconstructed value. Then, the second step uses confidence intervals as a constraint to choose the most appropriate candidate according to a regularization criterion. Two different constraints are proposed in this paper. The first one has the main advantage of strictly ensuring that the regularized solution will respect the interval-valued data-fitting constraint, thus preventing over-smoothing of the solution while offering interesting properties in terms of spatial and statistical bias/variance trade-off. Another regularization proposition based on the design of a smoother constraint also with appealing properties is proposed as an alternative. The competitiveness of the proposed framework is illustrated in comparison to other regularization schemes using analytical and GATE-based simulation and real PET acquisition.
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Durcanova B, Appleton J, Gurijala N, Belov V, Giffenig P, Moeller E, Hogan M, Lee F, Papisov M. The Configuration of the Perivascular System Transporting Macromolecules in the CNS. Front Neurosci 2019; 13:511. [PMID: 31191221 PMCID: PMC6547014 DOI: 10.3389/fnins.2019.00511] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 05/03/2019] [Indexed: 12/26/2022] Open
Abstract
Large blood vessels entering the CNS are surrounded by perivascular spaces that communicate with the cerebrospinal fluid and, at their termini, with the interstitial space. Solutes and particles can translocate along these perivascular conduits, reportedly in both directions. Recently, this prompted a renewed interest in the intrathecal therapy delivery route for CNS-targeted therapeutics. However, the extent of the CNS coverage by the perivascular system is unknown, making the outcome of drug administration to the CSF uncertain. We traced the translocation of model macromolecules from the CSF into the CNS of rats and non-human primates. Conduits transporting macromolecules were found to extend throughout the parenchyma from both external and internal (fissures) CNS boundaries, excluding ventricles, in large numbers, on average ca. 40 channels per mm2 in rats and non-human primates. The high density and depth of extension of the perivascular channels suggest that the perivascular route can be suitable for delivery of therapeutics to parenchymal targets throughout the CNS.
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Affiliation(s)
| | | | | | - Vasily Belov
- Massachusetts General Hospital, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States.,Shriners Hospitals for Children - Boston, Boston, MA, United States
| | - Pilar Giffenig
- Massachusetts General Hospital, Boston, MA, United States
| | | | - Matthew Hogan
- Massachusetts General Hospital, Boston, MA, United States
| | - Fredella Lee
- Massachusetts General Hospital, Boston, MA, United States
| | - Mikhail Papisov
- Massachusetts General Hospital, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States.,Shriners Hospitals for Children - Boston, Boston, MA, United States
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40
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Pei C, Baotong F, Zhiming Z, Haohui T, Shuangquan L, Xiaoli S, Peilin W, Xiaoming W, Xudong Z, Long W. NEMA NU-4 performance evaluation of a non-human primate animal PET. Phys Med Biol 2019; 64:105018. [PMID: 30947155 DOI: 10.1088/1361-6560/ab1614] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The Eplus-260 primate PET is an animal PET imaging system developed by the Institute of High Energy Physics, Chinese Academy of Sciences, which is designed to image non-human primates, especially the brain of large non-human primates. The system consists of 48 block detectors arranged in two 24-sided rings with a ring diameter of 263 mm and an axial extent of 64 mm. Each block detector is composed of a 16 × 16 cerium-doped lutetium-yttrium orthosilicate crystal array with a pixel size of 1.9 × 1.9 × 10 mm3. This article presents a performance evaluation of the PET scanner according to the National Electrical Manufacturers Association NU-4 2008 standards. All measurements were made for an energy window of 360-660 keV and a coincidence timing window of 2 ns. In terms of the FWHM, the FBP reconstructed spatial resolution results in all three directions at the radial position of 5 mm were better than or approached to 2 mm, and remained below 3.0 mm within the central 5 cm diameter of the FOV. The peak absolute sensitivity of the scanner was measured 1.80%. For a monkey-sized phantom, the scatter fraction was 34.2% and the peak noise equivalent count rate (NECR) was 26.5 kcps at 64.3 kBq/cc. The overall imaging capabilities of the scanner were also assessed using in vivo imaging study of a rhesus macaque. The performance measurements demonstrate that the Eplus-260 primate PET scanner has the potential ability to obtain good quality and high-contrast images for non-human primates, especially the brain of large non-human primates and could be considered as one technologically advanced dedicated non-human primate PET scanner available today.
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Affiliation(s)
- Chai Pei
- Beijing Engineering Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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Fractionating Blunted Reward Processing Characteristic of Anhedonia by Over-Activating Primate Subgenual Anterior Cingulate Cortex. Neuron 2018; 101:307-320.e6. [PMID: 30528065 PMCID: PMC6344231 DOI: 10.1016/j.neuron.2018.11.021] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/10/2018] [Accepted: 11/09/2018] [Indexed: 12/16/2022]
Abstract
Anhedonia is a core symptom of depression, but the underlying neurobiological mechanisms are unknown. Correlative neuroimaging studies implicate dysfunction within ventromedial prefrontal cortex, but the causal roles of specific subregions remain unidentified. We addressed these issues by combining intracerebral microinfusions with cardiovascular and behavioral monitoring in marmoset monkeys to show that over-activation of primate subgenual anterior cingulate cortex (sgACC, area 25) blunts appetitive anticipatory, but not consummatory, arousal, whereas manipulations of adjacent perigenual ACC (pgACC, area 32) have no effect. sgACC/25 over-activation also reduces the willingness to work for reward. 18F-FDG PET imaging reveals over-activation induced metabolic changes in circuits involved in reward processing and interoception. Ketamine treatment ameliorates the blunted anticipatory arousal and reverses associated metabolic changes. These results demonstrate a causal role for primate sgACC/25 over-activity in selective aspects of impaired reward processing translationally relevant to anhedonia, and ketamine's modulation of an affective network to exert its action.
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42
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Yoon C, Lee W. Performance Evaluation of Compton Micro-PET for Detector Modalities: A Monte Carlo Study. NUCL TECHNOL 2018. [DOI: 10.1080/00295450.2018.1493318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Changyeon Yoon
- Korea Hydro & Nuclear Power, Decommissioning Engineering Team, Daejeon 34101, Korea
- Korea University, Department of Bio-Convergence Engineering, Seoul 02841, Korea
| | - Wonho Lee
- Korea University, Department of Bio-Convergence Engineering, Seoul 02841, Korea
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43
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Huo L, Li N, Wu H, Zhu W, Xing H, Ba J, Wang T, Li F, Zhang H. Performance evaluation of a new high-sensitivity time-of-flight clinical PET/CT system. EJNMMI Phys 2018; 5:29. [PMID: 30506174 PMCID: PMC6269439 DOI: 10.1186/s40658-018-0229-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 08/09/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND PoleStar m660 is a newly developed clinical PET/CT system with time-of-flight (TOF) capability. The aim of this study is to characterize the performance of the new system. Spatial resolution, sensitivity, scatter fraction, and noise equivalent count rate (NECR) were measured on the scanner according to the NEMA NU 2-2012 protocol. The timing resolution was measured using a rotating line source that orbited around the center of field of view (CFOV) at a radius of 20 cm. The image quality phantom was also imaged to quantify the percent contrast, percent background variability, and residual error. The impacts of data acquisition time and bed overlap on the PET image quality were also evaluated using phantom and patient studies. RESULTS The transverse (axial) spatial resolutions were 3.59 mm (3.67), 4.08 mm (4.65), and 5.32 mm (6.48) full width at half maximum (FWHM) at 1 cm, 10 cm, and 20 cm, respectively, off the CFOV. The measured sensitivity was 10.7 cps/kBq at the CFOV and 10.4 cps/kBq at 10 cm off the CFOV. The peak NECR was 216.7 kcps at an activity concentration of 29.1 kBq/ml, and the scatter fraction was 38.2%. An average of 435 ps FWHM timing resolution was measured. For the image quality phantom, the contrast recovery ratios ranged from 33.9 to 76.4%, while the background variability ranged from 4.7 to 2.0%. In the preliminary clinical study, no noticeable difference in the image quality was observed when the scan time for the whole body and brain was reduced to 1 min/bed and 3 min, respectively. The tested 21% bed overlap showed no significant difference in the image quality compared with the default 38% bed overlap setting. CONCLUSIONS The physical performances of the PoleStar m660 PET/CT system showed good sensitivity, count rate performance, and timing resolution. The improved performance could help to reduce the acquisition time and bed overlap in the clinical application without detectable compromise in the image quality.
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Affiliation(s)
- Li Huo
- Department of Nuclear Medicine, Peking Union Medical College Hospital, Beijing, China
| | - Nan Li
- SinoUnion (Beijing) Healthcare Technologies Co., Ltd, Beijing, China
| | - Heyu Wu
- SinoUnion (Beijing) Healthcare Technologies Co., Ltd, Beijing, China
| | - Wenjia Zhu
- Department of Nuclear Medicine, Peking Union Medical College Hospital, Beijing, China
| | - Haiqun Xing
- Department of Nuclear Medicine, Peking Union Medical College Hospital, Beijing, China
| | - Jiantao Ba
- Department of Nuclear Medicine, Peking Union Medical College Hospital, Beijing, China
| | - Tong Wang
- Department of Nuclear Medicine, Peking Union Medical College Hospital, Beijing, China
| | - Fang Li
- Department of Nuclear Medicine, Peking Union Medical College Hospital, Beijing, China
| | - Hui Zhang
- Department of Biomedical Engineering, Tsinghua University, Beijing, China.
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Missault S, Anckaerts C, Blockx I, Deleye S, Van Dam D, Barriche N, De Pauw G, Aertgeerts S, Valkenburg F, De Deyn PP, Verhaeghe J, Wyffels L, Van der Linden A, Staelens S, Verhoye M, Dedeurwaerdere S. Neuroimaging of Subacute Brain Inflammation and Microstructural Changes Predicts Long-Term Functional Outcome after Experimental Traumatic Brain Injury. J Neurotrauma 2018; 36:768-788. [PMID: 30032713 DOI: 10.1089/neu.2018.5704] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
There is currently a lack of prognostic biomarkers to predict the different sequelae following traumatic brain injury (TBI). The present study investigated the hypothesis that subacute neuroinflammation and microstructural changes correlate with chronic TBI deficits. Rats were subjected to controlled cortical impact (CCI) injury, sham surgery, or skin incision (naïve). CCI-injured (n = 18) and sham-operated rats (n = 6) underwent positron emission tomography (PET) imaging with the translocator protein 18 kDa (TSPO) radioligand [18F]PBR111 and diffusion tensor imaging (DTI) in the subacute phase (≤3 weeks post-injury) to quantify inflammation and microstructural alterations. CCI-injured, sham-operated, and naïve rats (n = 8) underwent behavioral testing in the chronic phase (5.5-10 months post-injury): open field and sucrose preference tests, two one-week video-electroencephalogram (vEEG) monitoring periods, pentylenetetrazole (PTZ) seizure susceptibility tests, and a Morris water maze (MWM) test. In vivo imaging revealed pronounced neuroinflammation, decreased fractional anisotropy, and increased diffusivity in perilesional cortex and ipsilesional hippocampus of CCI-injured rats. Behavioral analysis revealed disinhibition, anhedonia, increased seizure susceptibility, and impaired learning in CCI-injured rats. Subacute TSPO expression and changes in DTI metrics significantly correlated with several chronic deficits (Pearson's |r| = 0.50-0.90). Certain specific PET and DTI parameters had good sensitivity and specificity (area under the receiver operator characteristic [ROC] curve = 0.85-1.00) to distinguish between TBI animals with and without particular behavioral deficits. Depending on the investigated behavioral deficit, PET or DTI data alone, or the combination, could very well predict the variability in functional outcome data (adjusted R2 = 0.54-1.00). Taken together, both TSPO PET and DTI seem promising prognostic biomarkers to predict different chronic TBI sequelae.
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Affiliation(s)
- Stephan Missault
- 1 Experimental Laboratory of Translational Neuroscience and Otolaryngology, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium .,2 Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Cynthia Anckaerts
- 2 Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Ines Blockx
- 2 Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Steven Deleye
- 3 Molecular Imaging Center Antwerp, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Debby Van Dam
- 4 Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, University of Antwerp, Wilrijk, Belgium; Department of Neurology and Alzheimer Research Center, University of Groningen and University Medical Center Groningen (UMCG) , Groningen, The Netherlands
| | - Nora Barriche
- 1 Experimental Laboratory of Translational Neuroscience and Otolaryngology, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Glenn De Pauw
- 1 Experimental Laboratory of Translational Neuroscience and Otolaryngology, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Stephanie Aertgeerts
- 1 Experimental Laboratory of Translational Neuroscience and Otolaryngology, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Femke Valkenburg
- 4 Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, University of Antwerp, Wilrijk, Belgium; Department of Neurology and Alzheimer Research Center, University of Groningen and University Medical Center Groningen (UMCG) , Groningen, The Netherlands
| | - Peter Paul De Deyn
- 4 Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, University of Antwerp, Wilrijk, Belgium; Department of Neurology and Alzheimer Research Center, University of Groningen and University Medical Center Groningen (UMCG) , Groningen, The Netherlands
| | - Jeroen Verhaeghe
- 3 Molecular Imaging Center Antwerp, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Leonie Wyffels
- 3 Molecular Imaging Center Antwerp, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium .,5 Department of Nuclear Medicine, University Hospital Antwerp , Edegem, Belgium
| | - Annemie Van der Linden
- 2 Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Steven Staelens
- 3 Molecular Imaging Center Antwerp, Faculty of Medicine and Health Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Marleen Verhoye
- 2 Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
| | - Stefanie Dedeurwaerdere
- 6 Laboratory of Experimental Hematology, Faculty of Medicine and Health Sciences, University of Antwerp , Wilrijk, Belgium
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Laymon CM, Minhas DS, Becker CR, Matan C, Oborski MJ, Price JC, Mountz JM. Image-Based 2D Re-Projection for Attenuation Substitution in PET Neuroimaging. Mol Imaging Biol 2018; 20:826-834. [PMID: 29488191 PMCID: PMC6354927 DOI: 10.1007/s11307-018-1171-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE In dual modality positron emission tomography (PET)/magnetic resonance imaging (MRI), attenuation correction (AC) methods are continually improving. Although a new AC can sometimes be generated from existing MR data, its application requires a new reconstruction. We evaluate an approximate 2D projection method that allows offline image-based reprocessing. PROCEDURE 2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) brain scans were acquired (Siemens HR+) for six subjects. Attenuation data were obtained using the scanner's transmission source (SAC). Additional scanning was performed on a Siemens mMR including production of a Dixon-based MR AC (MRAC). The MRAC was imported to the HR+ and the PET data were reconstructed twice: once using native SAC (ground truth); once using the imported MRAC (imperfect AC). The re-projection method was implemented as follows. The MRAC PET was forward projected to approximately reproduce attenuation-corrected sinograms. The SAC and MRAC images were forward projected and converted to attenuation-correction factors (ACFs). The MRAC ACFs were removed from the MRAC PET sinograms by division; the SAC ACFs were applied by multiplication. The regenerated sinograms were reconstructed by filtered back projection to produce images (SUBAC PET) in which SAC has been substituted for MRAC. Ideally SUBAC PET should match SAC PET. Via coregistered T1 images, FreeSurfer (FS; MGH, Boston) was used to define a set of cortical gray matter regions of interest. Regional activity concentrations were extracted for SAC PET, MRAC PET, and SUBAC PET. RESULTS SUBAC PET showed substantially smaller root mean square error than MRAC PET with averaged values of 1.5 % versus 8.1 %. CONCLUSIONS Re-projection is a viable image-based method for the application of an alternate attenuation correction in neuroimaging.
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Affiliation(s)
- Charles M Laymon
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Davneet S Minhas
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Carl R Becker
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Cristy Matan
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Matthew J Oborski
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Julie C Price
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - James M Mountz
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
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Hong X, Zan Y, Weng F, Tao W, Peng Q, Huang Q. Enhancing the Image Quality via Transferred Deep Residual Learning of Coarse PET Sinograms. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:2322-2332. [PMID: 29993685 DOI: 10.1109/tmi.2018.2830381] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Increasing the image quality of positron emission tomography (PET) is an essential topic in the PET community. For instance, thin-pixelated crystals have been used to provide high spatial resolution images but at the cost of sensitivity and manufacture expense. In this paper, we proposed an approach to enhance the PET image resolution and noise property for PET scanners with large pixelated crystals. To address the problem of coarse blurred sinograms with large parallax errors associated with large crystals, we developed a data-driven, single-image super-resolution (SISR) method for sinograms, based on the novel deep residual convolutional neural network (CNN). Unlike the CNN-based SISR on natural images, periodically padded sinogram data and dedicated network architecture were used to make it more efficient for PET imaging. Moreover, we included the transfer learning scheme in the approach to process cases with poor labeling and small training data set. The approach was validated via analytically simulated data (with and without noise), Monte Carlo simulated data, and pre-clinical data. Using the proposed method, we could achieve comparable image resolution and better noise property with large crystals of bin sizes of thin crystals with a bin size from to . Our approach uses external PET data as the prior knowledge for training and does not require additional information during inference. Meanwhile, the method can be added into the normal PET imaging framework seamlessly, thus potentially finds its application in designing low-cost high-performance PET systems.
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Augusto RS, Bauer J, Bouhali O, Cuccagna C, Gianoli C, Kozłowska WS, Ortega PG, Tessonnier T, Toufique Y, Vlachoudis V, Parodi K, Ferrari A. An overview of recent developments in FLUKA PET tools. Phys Med 2018; 54:189-199. [PMID: 30017561 DOI: 10.1016/j.ejmp.2018.06.636] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/25/2018] [Accepted: 06/22/2018] [Indexed: 12/19/2022] Open
Abstract
The new developments of the FLUKA Positron-Emission-Tomography (PET) tools are detailed. FLUKA is a fully integrated Monte Carlo (MC) particle transport code, used for an extended range of applications, including Medical Physics. Recently, it provided the medical community with dedicated simulation tools for clinical applications, including the PET simulation package. PET is a well-established imaging technique in nuclear medicine, and a promising method for clinical in vivo treatment verification in hadrontherapy. The application of clinically established PET scanners to new irradiation environments such as hadrontherapy requires further experimental and theoretical research to which MC simulations could be applied. The FLUKA PET tools, besides featuring PET scanner models in its library, allow the configuration of new PET prototypes via the FLUKA Graphical User Interface (GUI) Flair. Both the beam time structure and scan time can be specified by the user, reproducing PET acquisitions in time, in a particle therapy scenario. Furthermore, different scoring routines allow the analysis of single and coincident events, and identification of parent isotopes generating annihilation events. Two reconstruction codes are currently supported: the Filtered Back-Projection (FBP) and Maximum-Likelihood Expectation Maximization (MLEM), the latter embedded in the tools. Compatibility with other reconstruction frameworks is also possible. The FLUKA PET tools package has been successfully tested for different detectors and scenarios, including conventional functional PET applications and in beam PET, either using radioactive sources, or simulating hadron beam irradiations. The results obtained so far confirm the FLUKA PET tools suitability to perform PET simulations in R&D environment.
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Affiliation(s)
- R S Augusto
- CERN - European Organization for Nuclear Research, CH-1211 Genève 23, Switzerland; Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany.
| | - J Bauer
- UniversitätsKlinikum Heidelberg, Heidelberger Ionenstrahl-Therapiezentrum HIT, Germany
| | - O Bouhali
- Texas A&M University at Qatar, 23874 Doha, Qatar
| | - C Cuccagna
- CERN - European Organization for Nuclear Research, CH-1211 Genève 23, Switzerland; TERA Foundation, Via Puccini 11, 28100 Novara, Italy; Université de Genève, 30 quai Ernest-Ansermet, CH-1211 Genève, Switzerland
| | - C Gianoli
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany
| | - W S Kozłowska
- CERN - European Organization for Nuclear Research, CH-1211 Genève 23, Switzerland; Medizinische Universität Wien, Spitalgasse 23, 1090 Vienna, Austria
| | - P G Ortega
- Grupo de Física Nuclear, Universidad de Salamanca, E-37008 Salamanca, Spain
| | - T Tessonnier
- Centre François Baclesse, 3 Avenue du Général Harris, 14000 Caen, France
| | - Y Toufique
- Texas A&M University at Qatar, 23874 Doha, Qatar; Institut Superieur des Sciences de la Santé de Settat, Morocco
| | - V Vlachoudis
- CERN - European Organization for Nuclear Research, CH-1211 Genève 23, Switzerland
| | - K Parodi
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany
| | - A Ferrari
- CERN - European Organization for Nuclear Research, CH-1211 Genève 23, Switzerland
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One-pot enzymatic synthesis of l-[3- 11C]lactate for pharmacokinetic analysis of lactate metabolism in rat brain. Nucl Med Biol 2018; 64-65:28-33. [PMID: 30015093 DOI: 10.1016/j.nucmedbio.2018.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/17/2018] [Accepted: 07/04/2018] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Lactate could serve as an energy source and signaling molecule in the brain, although there is insufficient in vivo evidence to support this possibility. Here we aimed to use a one-pot enzymatic synthetic procedure to synthesize l-[3-11C]lactate that can be used to evaluate chemical forms in the blood after intravenous administration, and as a probe for pharmacokinetic analysis of lactate metabolism in in vivo positron emission tomography (PET) scans with normal and fasted rats. METHODS Racemic [3-11C]alanine obtained from 11C-methylation of a precursor and deprotection was reacted with an enzyme mixture consisting of alanine racemase, d-amino acid oxidase, catalase, and lactate dehydrogenase to yield l-[3-11C]lactate via [3-11C]pyruvate. The optical purity was measured by HPLC. Radioactive chemical forms in the arterial blood of Sprague Dawley rats with or without insulin pretreatment were evaluated by HPLC 10 min after bolus intravenous injection of l-[3-11C]lactate. PET scans were performed on normal and fasted rats administered with l-[3-11C]lactate. RESULTS l-[3-11C]Lactate was synthesized within 50 min and had decay corrected radiochemical yield, radiochemical purity, and optical purity of 13.4%, >95%, and >99%, respectively. The blood radioactivity peaked immediately after l-[3-11C]lactate injection, rapidly decreased to the minimum value within 90 s, and slowly cleared thereafter. HPLC analysis of blood samples revealed the presence of [11C]glucose (78.9%) and l-[3-11C]lactate (12.1%) 10 min after administration of l-[3-11C]lactate. Insulin pretreatment partly inhibited glyconeogenesis conversion leading to 55.4% as [11C]glucose and 38.9% as l-[3-11C]lactate simultaneously. PET analysis showed a higher SUV in the brain tissue of fasted rats relative to non-fasted rats. CONCLUSIONS We successfully synthesized l-[3-11C]lactate in a one-pot enzymatic synthetic procedure and showed rapid metabolic conversion of l-[3-11C]lactate to [11C]glucose in the blood. PET analysis of l-[3-11C]lactate indicated the possible presence of active lactate usage in rat brains in vivo.
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Dunn JT, Choudhary P, Teh MM, Macdonald I, Hunt KF, Marsden PK, Amiel SA. The impact of hypoglycaemia awareness status on regional brain responses to acute hypoglycaemia in men with type 1 diabetes. Diabetologia 2018; 61:1676-1687. [PMID: 29754288 PMCID: PMC6445483 DOI: 10.1007/s00125-018-4622-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/05/2018] [Indexed: 12/14/2022]
Abstract
AIMS/HYPOTHESIS Impaired awareness of hypoglycaemia (IAH) in type 1 diabetes increases the risk of severe hypoglycaemia sixfold and can be resistant to intervention. We explored the impact of IAH on central responses to hypoglycaemia to investigate the mechanisms underlying barriers to therapeutic intervention. METHODS We conducted [15O]water positron emission tomography studies of regional brain perfusion during euglycaemia (target 5 mmol/l), hypoglycaemia (achieved level, 2.4 mmol/l) and recovery (target 5 mmol/l) in 17 men with type 1 diabetes: eight with IAH, and nine with intact hypoglycaemia awareness (HA). RESULTS Hypoglycaemia with HA was associated with increased activation in brain regions including the thalamus, insula, globus pallidus (GP), anterior cingulate cortex (ACC), orbital cortex, dorsolateral frontal (DLF) cortex, angular gyrus and amygdala; deactivation occurred in the temporal and parahippocampal regions. IAH was associated with reduced catecholamine and symptom responses to hypoglycaemia vs HA (incremental AUC: autonomic scores, 26.2 ± 35.5 vs 422.7 ± 237.1; neuroglycopenic scores, 34.8 ± 88.8 vs 478.9 ± 311.1; both p < 0.002). There were subtle differences (p < 0.005, k ≥ 50 voxels) in brain activation at hypoglycaemia, including early differences in the right central operculum, bilateral medial orbital (MO) cortex, and left posterior DLF cortex, with additional differences in the ACC, right GP and post- and pre-central gyri in established hypoglycaemia, and lack of deactivation in temporal regions in established hypoglycaemia. CONCLUSIONS/INTERPRETATION Differences in activation in the post- and pre-central gyri may be expected in people with reduced subjective responses to hypoglycaemia. Alterations in the activity of regions involved in the drive to eat (operculum), emotional salience (MO cortex), aversion (GP) and recall (temporal) suggest differences in the perceived importance and urgency of responses to hypoglycaemia in IAH compared with HA, which may be key to the persistence of the condition.
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Affiliation(s)
- Joel T Dunn
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
| | - Pratik Choudhary
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK
- Institute of Diabetes and Obesity, King's Health Partners, London, UK
| | - Ming Ming Teh
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK
- Singapore General Hospital, Singapore, Republic of Singapore
| | - Ian Macdonald
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Katharine F Hunt
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK
- Institute of Diabetes and Obesity, King's Health Partners, London, UK
| | - Paul K Marsden
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
| | - Stephanie A Amiel
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK.
- Institute of Diabetes and Obesity, King's Health Partners, London, UK.
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McGinnity CJ, Riaño Barros DA, Trigg W, Brooks DJ, Hinz R, Duncan JS, Koepp MJ, Hammers A. Simplifying [ 18F]GE-179 PET: are both arterial blood sampling and 90-min acquisitions essential? EJNMMI Res 2018; 8:46. [PMID: 29892810 PMCID: PMC5995767 DOI: 10.1186/s13550-018-0396-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/08/2018] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION The NMDA receptor radiotracer [18F]GE-179 has been used with 90-min scans and arterial plasma input functions. We explored whether (1) arterial blood sampling is avoidable and (2) shorter scans are feasible. METHODS For 20 existing [18F]GE-179 datasets, we generated (1) standardised uptake values (SUVs) over eight intervals; (2) volume of distribution (VT) images using population-based input functions (PBIFs), scaled using one parent plasma sample; and (3) VT images using three shortened datasets, using the original parent plasma input functions (ppIFs). RESULTS Correlations with the original ppIF-derived 90-min VTs increased for later interval SUVs (maximal ρ = 0.78; 80-90 min). They were strong for PBIF-derived VTs (ρ = 0.90), but between-subject coefficient of variation increased. Correlations were very strong for the 60/70/80-min original ppIF-derived VTs (ρ = 0.97-1.00), which suffered regionally variant negative bias. CONCLUSIONS Where arterial blood sampling is available, reduction of scan duration to 60 min is feasible, but with negative bias. The performance of SUVs was more consistent across participants than PBIF-derived VTs.
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Affiliation(s)
- Colm J. McGinnity
- Division of Brain Sciences, Imperial College London, London, UK
- MRC Clinical Sciences Centre, London, UK
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor Lambeth Wing, St Thomas’ Hospital, Westminster Bridge Road, London, SW1 7EH UK
- King’s College London and Guy’s and St Thomas’ PET Centre, St. Thomas’ Hospital, London, UK
| | - Daniela A. Riaño Barros
- Division of Brain Sciences, Imperial College London, London, UK
- MRC Clinical Sciences Centre, London, UK
| | | | - David J. Brooks
- Department of Nuclear Medicine, Aarhus University, Aarhus, Denmark
- Institute of Neuroscience, University of Newcastle, Newcastle upon Tyne, UK
| | - Rainer Hinz
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK
| | - John S. Duncan
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
- Epilepsy Society, Buckinghamshire, UK
| | - Matthias J. Koepp
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
- Epilepsy Society, Buckinghamshire, UK
| | - Alexander Hammers
- Division of Brain Sciences, Imperial College London, London, UK
- MRC Clinical Sciences Centre, London, UK
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor Lambeth Wing, St Thomas’ Hospital, Westminster Bridge Road, London, SW1 7EH UK
- The Neurodis Foundation, CERMEP—Imagerie du Vivant, Lyon, France
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