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Choen S, Kent MS, Loucks FA, Winger JA, Zwingenberger AL. Assessment of tumor hypoxia in spontaneous canine tumors after treatment with OMX, a novel H-NOX oxygen carrier, with [ 18F]FMISO PET/CT. BMC Vet Res 2024; 20:196. [PMID: 38741109 PMCID: PMC11089780 DOI: 10.1186/s12917-024-04061-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 05/06/2024] [Indexed: 05/16/2024] Open
Abstract
BACKGROUND Hypoxia is a detrimental factor in solid tumors, leading to aggressiveness and therapy resistance. OMX, a tunable oxygen carrier from the heme nitric oxide/oxygen-binding (H-NOX) protein family, has the potential to reduce tumor hypoxia. [18F]Fluoromisonidazole ([18F]FMISO) positron emission tomography (PET) is the most widely used and investigated method for non-invasive imaging of tumor hypoxia. In this study, we used [18F]FMISO PET/CT (computed tomography) to assess the effect of OMX on tumor hypoxia in spontaneous canine tumors. RESULTS Thirteen canine patients with various tumors (n = 14) were randomly divided into blocks of two, with the treatment groups alternating between receiving intratumoral (IT) OMX injection (OMX IT group) and intravenous (IV) OMX injection (OMX IV group). Tumors were regarded as hypoxic if maximum tumor-to-muscle ratio (TMRmax) was greater than 1.4. In addition, hypoxic volume (HV) was defined as the region with tumor-to-muscle ratio greater than 1.4 on [18F]FMISO PET images. Hypoxia was detected in 6/7 tumors in the OMX IT group and 5/7 tumors in the OMX IV injection group. Although there was no significant difference in baseline hypoxia between the OMX IT and IV groups, the two groups showed different responses to OMX. In the OMX IV group, hypoxic tumors (n = 5) exhibited significant reductions in tumor hypoxia, as indicated by decreased TMRmax and HV in [18F]FMISO PET imaging after treatment. In contrast, hypoxic tumors in the OMX IT group (n = 6) displayed a significant increase in [18F]FMISO uptake and variable changes in TMRmax and HV. CONCLUSIONS [18F]FMISO PET/CT imaging presents a promising non-invasive procedure for monitoring tumor hypoxia and assessing the efficacy of hypoxia-modulating therapies in canine patients. OMX has shown promising outcomes in reducing tumor hypoxia, especially when administered intravenously, as evident from reductions in both TMRmax and HV in [18F]FMISO PET imaging.
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Affiliation(s)
- Sangkyung Choen
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave, 2112 Tupper Hall, Davis, CA, 95616, USA
| | - Michael S Kent
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave, 2112 Tupper Hall, Davis, CA, 95616, USA
| | | | | | - Allison L Zwingenberger
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave, 2112 Tupper Hall, Davis, CA, 95616, USA.
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He W, Zhao Y, Huang W, Zhao X, Niu M, Yang H, Zhang L, Ren Q, Gu Z. A multi-resolution TOF-DOI detector for human brain dedicated PET scanner. Phys Med Biol 2024; 69:025023. [PMID: 38181423 DOI: 10.1088/1361-6560/ad1b6b] [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: 07/31/2023] [Accepted: 01/05/2024] [Indexed: 01/07/2024]
Abstract
Objective. We propose a single-ended readout, multi-resolution detector design that can achieve high spatial, depth-of-interaction (DOI), and time-of-flight (TOF) resolutions, as well as high sensitivity for human brain-dedicated positron emission tomography (PET) scanners.Approach. The detector comprised two layers of LYSO crystal arrays and a lightguide in between. The top (gamma ray entrance) layer consisted of a 16 × 16 array of 1.53 × 1.53 × 6 mm3LYSO crystals for providing high spatial resolution. The bottom layer consisted of an 8 × 8 array of 3.0 × 3.0 × 15 mm3LYSO crystals that were one-to-one coupled to an 8 × 8 multipixel photon counter (MPPC) array for providing high TOF resolution. The 2 mm thick lightguide introduces inter-crystal light sharing that causes variations of the light distribution patterns for high DOI resolution. The detector was read out by a PETsys TOFPET2 application-specific integrated circuit.Main result. The top and bottom layers were distinguished by a convolutional neural network with 97% accuracy. All crystals in the top and bottom layers were resolved. The inter-crystal scatter (ICS) events in the bottom layer were identified, and the measured average DOI resolution of the bottom layer was 4.1 mm. The coincidence time resolution (CTR) for the top-top, top-bottom, and bottom-bottom coincidences was 476 ps, 405 ps, and 298 ps, respectively. When ICS events were excluded from the bottom layer, the CTR of the bottom-bottom coincidence was 277 ps.Significance. The top layer of the proposed two-layer detector achieved a high spatial resolution and the bottom layer achieved a high TOF resolution. Together with its high DOI resolution and detection efficiency, the proposed detector is well suited for next-generation high-performance brain-dedicated PET scanners.
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Affiliation(s)
- Wen He
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
| | - Yangyang Zhao
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Wenjie Huang
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Xin Zhao
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Ming Niu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Hang Yang
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Lei Zhang
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
- Institute of Cancer Research, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Qiushi Ren
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
| | - Zheng Gu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
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Fang L, Zhang B, Li B, Zhang X, Zhou X, Yang J, Li A, Shi X, Liu Y, Kreissl M, D'Ascenzo N, Xiao P, Xie Q. Development and evaluation of a new high-TOF-resolution all-digital brain PET system. Phys Med Biol 2024; 69:025019. [PMID: 38100841 DOI: 10.1088/1361-6560/ad164d] [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: 07/15/2023] [Accepted: 12/15/2023] [Indexed: 12/17/2023]
Abstract
Objective.Time-of-flight (TOF) capability and high sensitivity are essential for brain-dedicated positron emission tomography (PET) imaging, as they improve the contrast and the signal-to-noise ratio (SNR) enabling a precise localization of functional mechanisms in the different brain regions.Approach.We present a new brain PET system with transverse and axial field-of-view (FOV) of 320 mm and 255 mm, respectively. The system head is an array of 6 × 6 detection elements, each consisting of a 3.9 × 3.9 × 20 mm3lutetium-yttrium oxyorthosilicate crystal coupled with a 3.93 × 3.93 mm2SiPM. The SiPMs analog signals are individually digitized using the multi-voltage threshold (MVT) technology, employing a 1:1:1 coupling configuration.Main results.The brain PET system exhibits a TOF resolution of 249 ps at 5.3 kBq ml-1, an average sensitivity of 22.1 cps kBq-1, and a noise equivalent count rate (NECR) peak of 150.9 kcps at 8.36 kBq ml-1. Furthermore, the mini-Derenzo phantom study demonstrated the system's ability to distinguish rods with a diameter of 2.0 mm. Moreover, incorporating the TOF reconstruction algorithm in an image quality phantom study optimizes the background variability, resulting in reductions ranging from 44% (37 mm) to 75% (10 mm) with comparable contrast. In the human brain imaging study, the SNR improved by a factor of 1.7 with the inclusion of TOF, increasing from 27.07 to 46.05. Time-dynamic human brain imaging was performed, showing the distinctive traits of cortex and thalamus uptake, as well as of the arterial and venous flow with 2 s per time frame.Significance.The system exhibited a good TOF capability, which is coupled with the high sensitivity and count rate performance based on the MVT digital sampling technique. The developed TOF-enabled brain PET system opens the possibility of precise kinetic brain PET imaging, towards new quantitative predictive brain diagnostics.
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Affiliation(s)
- Lei Fang
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Bo Zhang
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Bingxuan Li
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, Anhui, People's Republic of China
| | - Xiangsong Zhang
- Department of Nuclear Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Xiaoyun Zhou
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Jigang Yang
- Department of Nuclear Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Ang Li
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Xinchong Shi
- Department of Nuclear Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Yuqing Liu
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, Anhui, People's Republic of China
| | - Michael Kreissl
- Division of Nuclear Medicine, Deprtment of Radiology and Nuclear Medicine, University Hospital Magdeburg, Otto-von-Guericke University, Magdeburg, Germany
- Research Campus STIMULATE, Otto-von-Guericke University, Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Nicola D'Ascenzo
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
- Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
- Department of Innovation in Engineering and Physics, Istituto Neurologico Mediterraneo NEUROMED I.R.C.C.S., Pozzilli, Italy
| | - Peng Xiao
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
- Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Qingguo Xie
- Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
- Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
- Department of Innovation in Engineering and Physics, Istituto Neurologico Mediterraneo NEUROMED I.R.C.C.S., Pozzilli, Italy
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Triumbari EKA, Rufini V, Mingels C, Rominger A, Alavi A, Fanfani F, Badawi RD, Nardo L. Long Axial Field-of-View PET/CT Could Answer Unmet Needs in Gynecological Cancers. Cancers (Basel) 2023; 15:2407. [PMID: 37173874 PMCID: PMC10177015 DOI: 10.3390/cancers15092407] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 04/15/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
Gynecological malignancies currently affect about 3.5 million women all over the world. Imaging of uterine, cervical, vaginal, ovarian, and vulvar cancer still presents several unmet needs when using conventional modalities such as ultrasound, computed tomography (CT), magnetic resonance, and standard positron emission tomography (PET)/CT. Some of the current diagnostic limitations are represented by differential diagnosis between inflammatory and cancerous findings, detection of peritoneal carcinomatosis and metastases <1 cm, detection of cancer-associated vascular complications, effective assessment of post-therapy changes, as well as bone metabolism and osteoporosis assessment. As a result of recent advances in PET/CT instrumentation, new systems now offer a long-axial field-of-view (LAFOV) to image between 106 cm and 194 cm (i.e., total-body PET) of the patient's body simultaneously and feature higher physical sensitivity and spatial resolution compared to standard PET/CT systems. LAFOV PET could overcome the forementioned limitations of conventional imaging and provide valuable global disease assessment, allowing for improved patient-tailored care. This article provides a comprehensive overview of these and other potential applications of LAFOV PET/CT imaging for patients with gynecological malignancies.
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Affiliation(s)
- Elizabeth Katherine Anna Triumbari
- Nuclear Medicine Unit, G-STeP Radiopharmacy Research Core Facility, Department of Radiology, Radiotherapy and Haematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
| | - Vittoria Rufini
- Nuclear Medicine Unit, Department of Radiology, Radiotherapy and Haematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo A. Gemelli, 8, 00168 Rome, Italy
- Section of Nuclear Medicine, Department of Radiological Sciences, Radiotherapy and Haematology, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Clemens Mingels
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
| | - Axel Rominger
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
| | - Abass Alavi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Francesco Fanfani
- Woman, Child and Public Health Department, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
- Section of Obstetrics and Gynaecology, University Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, 00168 Roma, Italy
| | - Ramsey D. Badawi
- Department of Radiology, University of California Davis, Sacramento, CA 95819, USA
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Lorenzo Nardo
- Department of Radiology, University of California Davis, Sacramento, CA 95819, USA
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Choen S, Kent MS, Chaudhari AJ, Cherry SR, Krtolica A, Zwingenberger AL. Kinetic Evaluation of the Hypoxia Radiotracers [ 18F]FMISO and [ 18F]FAZA in Dogs with Spontaneous Tumors Using Dynamic PET/CT Imaging. Nucl Med Mol Imaging 2023; 57:16-25. [PMID: 36643946 PMCID: PMC9832187 DOI: 10.1007/s13139-022-00780-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/12/2022] [Accepted: 09/28/2022] [Indexed: 02/01/2023] Open
Abstract
Purpose We evaluated the kinetics of the hypoxia PET radiotracers, [18F]fluoromisonidazole ([18F]FMISO) and [18F]fluoroazomycin-arabinoside ([18F]FAZA), for tumor hypoxia detection and to assess the correlation of hypoxic kinetic parameters with static imaging measures in canine spontaneous tumors. Methods Sixteen dogs with spontaneous tumors underwent a 150-min dynamic PET scan using either [18F]FMISO or [18F]FAZA. The maximum tumor-to-muscle ratio (TMRmax) > 1.4 on the last image frame was used as the standard threshold to determine tumor hypoxia. The tumor time-activity curves were analyzed using irreversible and reversible two-tissue compartment models and graphical methods. TMRmax was compared with radiotracer trapping rate (k 3), influx rate (K i), and distribution volume (V T). Results Tumor hypoxia was detected in 7/8 tumors in the [18F]FMISO group and 4/8 tumors in the [18F]FAZA group. All hypoxic tumors were detected at > 120 min with [18F]FMISO and at > 60 min with [18F]FAZA. [18F]FAZA showed better fit with the reversible model. TMRmax was strongly correlated with the irreversible parameters (k 3 and K i) for [18F]FMISO at > 90 min and with the reversible parameter (V T) for [18F]FAZA at > 120 min. Conclusions Our results showed that [18F]FAZA provided a promising alternative radiotracer to [18F]FMISO with detecting the presence of tumor hypoxia at an earlier time (60 min), consistent with its favorable faster kinetics. The strong correlation between TMRmax over the 90-150 min and 120-150 min timeframes with [18F]FMISO and [18F]FAZA, respectively, with kinetic parameters associated with tumor hypoxia for each radiotracer, suggests that a static scan measurement (TMRmax) is a good alternative to quantify tumor hypoxia. Supplementary Information The online version contains supplementary material available at 10.1007/s13139-022-00780-4.
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Affiliation(s)
- Sangkyung Choen
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA USA
| | - Michael S. Kent
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA USA
| | - Abhijit J. Chaudhari
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA USA ,Department of Radiology, School of Medicine, University of California, CA Sacramento, USA
| | - Simon R. Cherry
- Department of Biomedical Engineering, College of Engineering, University of California, Davis, CA USA
| | | | - Allison L. Zwingenberger
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA USA
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Du J, Jones T. Technical opportunities and challenges in developing total-body PET scanners for mice and rats. EJNMMI Phys 2023; 10:2. [PMID: 36592266 PMCID: PMC9807733 DOI: 10.1186/s40658-022-00523-6] [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] [Received: 12/09/2021] [Accepted: 12/20/2022] [Indexed: 01/03/2023] Open
Abstract
Positron emission tomography (PET) is the most sensitive in vivo molecular imaging technique available. Small animal PET has been widely used in studying pharmaceutical biodistribution and disease progression over time by imaging a wide range of biological processes. However, it remains true that almost all small animal PET studies using mouse or rat as preclinical models are either limited by the spatial resolution or the sensitivity (especially for dynamic studies), or both, reducing the quantitative accuracy and quantitative precision of the results. Total-body small animal PET scanners, which have axial lengths longer than the nose-to-anus length of the mouse/rat and can provide high sensitivity across the entire body of mouse/rat, can realize new opportunities for small animal PET. This article aims to discuss the technical opportunities and challenges in developing total-body small animal PET scanners for mice and rats.
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Affiliation(s)
- Junwei Du
- grid.27860.3b0000 0004 1936 9684Department of Biomedical Engineering, University of California at Davis, Davis, CA 95616 USA
| | - Terry Jones
- grid.27860.3b0000 0004 1936 9684Department of Radiology, University of California at Davis, Davis, CA 95616 USA
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Merchant SA, Shaikh MJS, Nadkarni P. Tuberculosis conundrum - current and future scenarios: A proposed comprehensive approach combining laboratory, imaging, and computing advances. World J Radiol 2022; 14:114-136. [PMID: 35978978 PMCID: PMC9258306 DOI: 10.4329/wjr.v14.i6.114] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 04/17/2022] [Accepted: 05/28/2022] [Indexed: 02/06/2023] Open
Abstract
Tuberculosis (TB) remains a global threat, with the rise of multiple and extensively drug resistant TB posing additional challenges. The International health community has set various 5-yearly targets for TB elimination: mathematical modelling suggests that a 2050 target is feasible with a strategy combining better diagnostics, drugs, and vaccines to detect and treat both latent and active infection. The availability of rapid and highly sensitive diagnostic tools (Gene-Xpert, TB-Quick) will vastly facilitate population-level identification of TB (including rifampicin resistance and through it, multi-drug-resistant TB). Basic-research advances have illuminated molecular mechanisms in TB, including the protective role of Vitamin D. Also, Mycobacterium tuberculosis impairs the host immune response through epigenetic mechanisms (histone-binding modulation). Imaging will continue to be key, both for initial diagnosis and follow-up. We discuss advances in multiple imaging modalities to evaluate TB tissue changes, such as molecular imaging techniques (including pathogen-specific positron emission tomography imaging agents), non-invasive temporal monitoring, and computing enhancements to improve data acquisition and reduce scan times. Big data analysis and Artificial Intelligence (AI) algorithms, notably in the AI sub-field called “Deep Learning”, can potentially increase the speed and accuracy of diagnosis. Additionally, Federated learning makes multi-institutional/multi-city AI-based collaborations possible without sharing identifiable patient data. More powerful hardware designs - e.g., Edge and Quantum Computing- will facilitate the role of computing applications in TB. However, “Artificial Intelligence needs real Intelligence to guide it!” To have maximal impact, AI must use a holistic approach that incorporates time tested human wisdom gained over decades from the full gamut of TB, i.e., key imaging and clinical parameters, including prognostic indicators, plus bacterial and epidemiologic data. We propose a similar holistic approach at the level of national/international policy formulation and implementation, to enable effective culmination of TB’s endgame, summarizing it with the acronym “TB - REVISITED”.
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Affiliation(s)
- Suleman Adam Merchant
- Lokmanya Tilak Municipal Medical College and General Hospital, Mumbai 400022, Maharashtra, India
| | - Mohd Javed Saifullah Shaikh
- Department of Radiology, North Bengal Neuro Centre, Jupiter magnetic resonance imaging, Diagnostic Centre, Siliguri 734003, West Bengal, India
| | - Prakash Nadkarni
- College of Nursing, University of Iowa, Iowa 52242, IA, United States
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Nadig V, Herrmann K, Mottaghy FM, Schulz V. Hybrid total-body pet scanners-current status and future perspectives. Eur J Nucl Med Mol Imaging 2022; 49:445-459. [PMID: 34647154 PMCID: PMC8803785 DOI: 10.1007/s00259-021-05536-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 08/20/2021] [Indexed: 12/18/2022]
Abstract
Purpose Since the 1990s, PET has been successfully combined with MR or CT systems. In the past years, especially PET systems have seen a trend towards an enlarged axial field of view (FOV), up to a factor of ten. Methods Conducting a thorough literature research, we summarize the status quo of contemporary total-body (TB) PET/CT scanners and give an outlook on possible future developments. Results Currently, three human TB PET/CT systems have been developed: The PennPET Explorer, the uExplorer, and the Biograph Vision Quadra realize aFOVs between 1 and 2 m and show a tremendous increase in system sensitivity related to their longer gantries. Conclusion The increased system sensitivity paves the way for short-term, low-dose, and dynamic TB imaging as well as new examination methods in almost all areas of imaging.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, University of Duisburg-Essen, Duisburg, Germany
- German Cancer Consortium (DKTK) - University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Felix M Mottaghy
- Department of Nuclear Medicine, University Hospital Aachen, RWTH Aachen University, Aachen, Germany
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.
- Physics Institute III B, RWTH Aachen University, Aachen, Germany.
- Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany.
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Abstract
Abstract
In this partial review and partial attempt at vision of what may be the future of dedicated brain PET scanners, the key implementations of the PET technique, we postulate that we are still on a development path and there is still a lot to be done in order to develop optimal brain imagers. Optimized for particular imaging tasks and protocols, and also mobile, that can be used outside the PET center, in addition to the expected improvements in sensitivity and resolution. For this multi-application concept to be more practical, flexible, adaptable designs are preferred. This task is greatly facilitated by the improved TOF performance that allows for more open, adjustable, limited angular coverage geometries without creating image artifacts. As achieving uniform very high resolution in the whole body is not practical due to technological limits and high costs, hybrid systems using a moderate-resolution total body scanner (such as J-PET) combined with a very high performing brain imager could be a very attractive approach. As well, as using magnification inserts in the total body or long-axial length imagers to visualize selected targets with higher resolution. In addition, multigamma imagers combining PET with Compton imaging should be developed to enable multitracer imaging.
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Bebié P, Becker R, Commichau V, Debus J, Dissertori G, Djambazov L, Eleftheriou A, Fischer J, Fischer P, Ito M, Khateri P, Lustermann W, Ritzer C, Ritzert M, Röser U, Tsoumpas C, Warnock G, Weber B, Wyss MT, Zagozdzinska-Bochenek A. SAFIR-I: Design and Performance of a High-Rate Preclinical PET Insert for MRI. SENSORS (BASEL, SWITZERLAND) 2021; 21:7037. [PMID: 34770344 PMCID: PMC8588038 DOI: 10.3390/s21217037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/15/2021] [Accepted: 10/19/2021] [Indexed: 11/16/2022]
Abstract
(1) Background: Small Animal Fast Insert for MRI detector I (SAFIR-I) is a preclinical Positron Emission Tomography (PET) insert for the Bruker BioSpec 70/30 Ultra Shield Refrigerated (USR) preclinical 7T Magnetic Resonance Imaging (MRI) system. It is designed explicitly for high-rate kinetic studies in mice and rats with injected activities reaching 500MBq, enabling truly simultaneous quantitative PET and Magnetic Resonance (MR) imaging with time frames of a few seconds in length. (2) Methods: SAFIR-I has an axial field of view of 54.2mm and an inner diameter of 114mm. It employs Lutetium Yttrium OxyorthoSilicate (LYSO) crystals and Multi Pixel Photon Counter (MPPC) arrays. The Position-Energy-Timing Application Specific Integrated Circuit, version 6, Single Ended (PETA6SE) digitizes the MPPC signals and provides time stamps and energy information. (3) Results: SAFIR-I is MR-compatible. The system's Coincidence Resolving Time (CRT) and energy resolution are between separate-uncertainty 209.0(3)ps and separate-uncertainty 12.41(02) Full Width at Half Maximum (FWHM) at low activity and separate-uncertainty 326.89(12)ps and separate-uncertainty 20.630(011) FWHM at 550MBq, respectively. The peak sensitivity is ∼1.6. The excellent performance facilitated the successful execution of first in vivo rat studies beyond 300MBq. Based on features visible in the acquired images, we estimate the spatial resolution to be ∼2mm in the center of the Field Of View (FOV). (4) Conclusion: The SAFIR-I PET insert provides excellent performance, permitting simultaneous in vivo small animal PET/MR image acquisitions with time frames of a few seconds in length at activities of up to 500MBq.
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Affiliation(s)
- Pascal Bebié
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Robert Becker
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Volker Commichau
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Jan Debus
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Günther Dissertori
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Lubomir Djambazov
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Afroditi Eleftheriou
- Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland; (A.E.); (G.W.); (B.W.); (M.T.W.)
| | - Jannis Fischer
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Peter Fischer
- Institute of Computer Engineering, Heidelberg University, 69120 Heidelberg, Germany; (P.F.); (M.R.)
| | - Mikiko Ito
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Parisa Khateri
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Werner Lustermann
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Christian Ritzer
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Michael Ritzert
- Institute of Computer Engineering, Heidelberg University, 69120 Heidelberg, Germany; (P.F.); (M.R.)
| | - Ulf Röser
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
| | - Charalampos Tsoumpas
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK;
| | - Geoffrey Warnock
- Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland; (A.E.); (G.W.); (B.W.); (M.T.W.)
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland; (A.E.); (G.W.); (B.W.); (M.T.W.)
| | - Matthias T. Wyss
- Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland; (A.E.); (G.W.); (B.W.); (M.T.W.)
| | - Agnieszka Zagozdzinska-Bochenek
- Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich, Switzerland; (R.B.); (V.C.); (J.D.); (G.D.); (L.D.); (J.F.); (M.I.); (P.K.); (W.L.); (C.R.); (U.R.); (A.Z.-B.)
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11
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Won JY, Park H, Lee S, Son JW, Chung Y, Ko GB, Kim KY, Song J, Seo S, Ryu Y, Chung JY, Lee JS. Development and Initial Results of a Brain PET Insert for Simultaneous 7-Tesla PET/MRI Using an FPGA-Only Signal Digitization Method. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:1579-1590. [PMID: 33625980 DOI: 10.1109/tmi.2021.3062066] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In study, we developed a positron emission tomography (PET) insert for simultaneous brain imaging within 7-Tesla (7T) magnetic resonance (MR) imaging scanners. The PET insert has 18 sectors, and each sector is assembled with two-layer depth-of-interaction (DOI)-capable high-resolution block detectors. The PET scanner features a 16.7-cm-long axial field-of-view (FOV) to provide entire human brain images without bed movement. The PET scanner early digitizes a large number of block detector signals at a front-end data acquisition (DAQ) board using a novel field-programmable gate array (FPGA)-only signal digitization method. All the digitized PET data from the front-end DAQ boards are transferred using gigabit transceivers via non-magnetic high-definition multimedia interface (HDMI) cables. A back-end DAQ system provides a common clock and synchronization signal for FPGAs over the HDMI cables. An active cooling system using copper heat pipes is applied for thermal regulation. All the 2.17-mm-pitch crystals with two-layer DOI information were clearly identified in the block detectors, exhibiting a system-level energy resolution of 12.6%. The PET scanner yielded clear hot-rod and Hoffman brain phantom images and demonstrated 3D PET imaging capability without bed movement. We also performed a pilot simultaneous PET/MR imaging study of a brain phantom. The PET scanner achieved a spatial resolution of 2.5 mm at the center FOV (NU 4) and a sensitivity of 18.9 kcps/MBq (NU 2) and 6.19% (NU 4) in accordance with the National Electrical Manufacturers Association (NEMA) standards.
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12
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Chaudhari AJ, Badawi RD. Application-specific nuclear medical in vivoimaging devices. Phys Med Biol 2021; 66. [PMID: 33770765 DOI: 10.1088/1361-6560/abf275] [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: 11/05/2019] [Accepted: 03/26/2021] [Indexed: 11/11/2022]
Abstract
Nuclear medical imaging devices, such as those enabling photon emission imaging (gamma camera, single photon emission computed tomography, or positron emission imaging), that are typically used in today's clinics are optimized for assessing large portions of the human body, and are classified as whole-body imaging systems. These systems have known limitations for organ imaging, therefore application-specific devices have been designed, constructed and evaluated. These devices, given their compact nature and superior technical characteristics, such as their higher detection sensitivity and spatial resolution for organ imaging compared to whole-body imaging systems, have shown promise for niche applications. Several of these devices have further been integrated with complementary anatomical imaging devices. The objectives of this review article are to (1) provide an overview of such application-specific nuclear imaging devices that were developed over the past two decades (in the twenty-first century), with emphasis on brain, cardiac, breast, and prostate imaging; and (2) discuss the rationale, advantages and challenges associated with the translation of these devices for routine clinical imaging. Finally, a perspective on the future prospects for application-specific devices is provided, which is that sustained effort is required both to overcome design limitations which impact their utility (where these exist) and to collect the data required to define their clinical value.
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Affiliation(s)
- Abhijit J Chaudhari
- Department of Radiology, University of California Davis, Sacramento, CA 95817, United States of America.,Center for Molecular and Genomic Imaging, University of California Davis, Davis, CA 95616, United States of America
| | - Ramsey D Badawi
- Department of Radiology, University of California Davis, Sacramento, CA 95817, United States of America.,Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
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13
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Du J, Cherry S. A high resolution and high detection efficiency depth-encoding detector for brain positron emission tomography based on a 0.75 mm pitch scintillator array. JOURNAL OF INSTRUMENTATION : AN IOP AND SISSA JOURNAL 2021; 16:P05015. [PMID: 34925535 PMCID: PMC8681625 DOI: 10.1088/1748-0221/16/05/p05015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The quantitative accuracy and precision of brain positron emission tomography (PET) studies can be considerably improved using dedicated brain PET scanners with a uniform high resolution and a high sensitivity across the brain volume. One approach to building such a system is to construct the PET scanner using depth-of-interaction (DOI) encoding detectors with finely segmented and thick crystal arrays. In this paper, the performance of a DOI PET detector based on two 16 × 16 arrays of 2 × 2 mm2 SiPMs coupled to both ends of a 44 × 44 array of 0.69 × 0.69 × 30 mm3 polished LYSO crystals was evaluated at different temperatures (-9°C, 0°C, 10°C, and 20°C) for brain PET applications. The pitch size of the LYSO array is 0.75 mm. The flood histograms show that all the crystal elements in the LYSO array can be resolved except some edge crystals, due to the limited light sharing. The average energy resolution, average DOI resolution, and average timing resolution across crystal elements are 21.1 ± 3.0%, 3.47 ± 0.17 mm, and 1.38 ± 0.09 ns, respectively, which were obtained at a bias voltage of 56.5 V and a temperature of 0°C.
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Affiliation(s)
- J. Du
- Department of Biomedical Engineering, University of California at Davis, Davis, California 95616, U.S.A
| | - S.R. Cherry
- Department of Biomedical Engineering, University of California at Davis, Davis, California 95616, U.S.A
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14
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Ota R. Photon counting detectors and their applications ranging from particle physics experiments to environmental radiation monitoring and medical imaging. Radiol Phys Technol 2021; 14:134-148. [PMID: 33742329 DOI: 10.1007/s12194-021-00615-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 01/01/2023]
Abstract
Photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) have played essential roles in various applications, such as fundamental particle physics experiments, nuclear medicine, and environmental radiation monitoring, for several decades. Understandings their physical properties as well as present applications is indispensable for the development and future applications of these detectors. In this review, we describe the physical principles of PMTs and SiPMs and introduce various applications of these detectors.
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Affiliation(s)
- Ryosuke Ota
- Central Research Laboratory, Hamamatsu Photonics K. K, Hamamatsu, Japan. .,, 5000, Hirakuchi, Hamakita-ku, Hamamatsu, 434-8601, Japan.
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15
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Lai Y, Wang Q, Zhou S, Xie Z, Qi J, Cherry SR, Jin M, Chi Y, Du J. H 2RSPET: a 0.5 mm resolution high-sensitivity small-animal PET scanner, a simulation study. Phys Med Biol 2021; 66:065016. [PMID: 33571980 DOI: 10.1088/1361-6560/abe558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
With the goal of developing a total-body small-animal PET system with a high spatial resolution of ∼0.5 mm and a high sensitivity >10% for mouse/rat studies, we simulated four scanners using the graphical processing unit-based Monte Carlo simulation package (gPET) and compared their performance in terms of spatial resolution and sensitivity. We also investigated the effect of depth-of-interaction (DOI) resolution on the spatial resolution. All the scanners are built upon 128 DOI encoding dual-ended readout detectors with lutetium yttrium oxyorthosilicate (LYSO) arrays arranged in 8 detector rings. The solid angle coverages of the four scanners are all ∼0.85 steradians. Each LYSO element has a cross-section of 0.44 × 0.44 mm2 and the pitch size of the LYSO arrays are all 0.5 mm. The four scanners can be divided into two groups: (1) H2RS110-C10 and H2RS110-C20 with 40 × 40 LYSO arrays, a ring diameter of 110 mm and axial length of 167 mm, and (2) H2RS160-C10 and H2RS160-C20 with 60 × 60 LYSO arrays, a diameter of 160 mm and axial length of 254 mm. C10 and C20 denote the crystal thickness of 10 and 20 mm, respectively. The simulation results show that all scanners have a spatial resolution better than 0.5 mm at the center of the field-of-view (FOV). The radial resolution strongly depends on the DOI resolution and radial offset, but not the axial resolution and tangential resolution. Comparing the C10 and C20 designs, the former provides better resolution, especially at positions away from the center of the FOV, whereas the latter has 2× higher sensitivity (∼10% versus ∼20%). This simulation study provides evidence that the 110 mm systems are a good choice for total-body mouse studies at a lower cost, whereas the 160 mm systems are suited for both total-body mouse and rat studies.
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Affiliation(s)
- Youfang Lai
- Department of Physics, University of Texas at Arlington, Arlington, TX 76019, United States of America
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16
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Ordonez AA, Tucker EW, Anderson CJ, Carter CL, Ganatra S, Kaushal D, Kramnik I, Lin PL, Madigan CA, Mendez S, Rao J, Savic RM, Tobin DM, Walzl G, Wilkinson RJ, Lacourciere KA, Via LE, Jain SK. Visualizing the dynamics of tuberculosis pathology using molecular imaging. J Clin Invest 2021; 131:145107. [PMID: 33645551 PMCID: PMC7919721 DOI: 10.1172/jci145107] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Nearly 140 years after Robert Koch discovered Mycobacterium tuberculosis, tuberculosis (TB) remains a global threat and a deadly human pathogen. M. tuberculosis is notable for complex host-pathogen interactions that lead to poorly understood disease states ranging from latent infection to active disease. Additionally, multiple pathologies with a distinct local milieu (bacterial burden, antibiotic exposure, and host response) can coexist simultaneously within the same subject and change independently over time. Current tools cannot optimally measure these distinct pathologies or the spatiotemporal changes. Next-generation molecular imaging affords unparalleled opportunities to visualize infection by providing holistic, 3D spatial characterization and noninvasive, temporal monitoring within the same subject. This rapidly evolving technology could powerfully augment TB research by advancing fundamental knowledge and accelerating the development of novel diagnostics, biomarkers, and therapeutics.
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Affiliation(s)
- Alvaro A. Ordonez
- Center for Infection and Inflammation Imaging Research
- Center for Tuberculosis Research
- Department of Pediatrics, and
| | - Elizabeth W. Tucker
- Center for Infection and Inflammation Imaging Research
- Center for Tuberculosis Research
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Claire L. Carter
- Hackensack Meridian Health Center for Discovery and Innovation, Nutley, New Jersey, USA
| | - Shashank Ganatra
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Deepak Kaushal
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Igor Kramnik
- Pulmonary Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusets, USA
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, USA
| | - Philana L. Lin
- Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Cressida A. Madigan
- Department of Biological Sciences, UCSD, San Diego, La Jolla, California, USA
| | - Susana Mendez
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Rockville, Maryland, USA
| | - Jianghong Rao
- Molecular Imaging Program at Stanford, Department of Radiology and Chemistry, Stanford University, Stanford, California, USA
| | - Rada M. Savic
- Department of Bioengineering and Therapeutic Sciences, School of Pharmacy and Medicine, UCSF, San Francisco, California, USA
| | - David M. Tobin
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Gerhard Walzl
- SAMRC Centre for Tuberculosis Research, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Department of Biomedical Sciences, Stellenbosch University, Cape Town, South Africa
| | - Robert J. Wilkinson
- Department of Infectious Diseases, Imperial College London, London, United Kingdom
- Wellcome Centre for Infectious Diseases Research in Africa and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
- The Francis Crick Institute, London, United Kingdom
| | - Karen A. Lacourciere
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Rockville, Maryland, USA
| | - Laura E. Via
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, and Tuberculosis Imaging Program, Division of Intramural Research, NIAID, NIH, Bethesda, Maryland, USA
| | - Sanjay K. Jain
- Center for Infection and Inflammation Imaging Research
- Center for Tuberculosis Research
- Department of Pediatrics, and
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17
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Ghabrial A, Franklin DR, Zaidi H. A Monte Carlo simulation study of scatter fraction and the impact of patient BMI on scatter in long axial field-of-view PET scanners. Z Med Phys 2021; 31:305-315. [PMID: 33593642 DOI: 10.1016/j.zemedi.2021.01.006] [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: 04/20/2020] [Revised: 01/24/2021] [Accepted: 01/25/2021] [Indexed: 11/16/2022]
Abstract
The NEMA NU-2 standard describes a protocol for measurement of scatter fraction (SF) using an axially-aligned line source, offset at 45mm from the central axis, in a cylindrical polyethylene phantom. In this work, which is an extension of our preliminary results previuosly published in the Proceedings of IEEE NSS/MIC 2018 [1], we aim to evaluate the performance of the NEMA NU-2 SF protocol in a Siemens Biograph mCT PET/CT whole-body scanner and a long axial field-of-view (LAFOV) total-body PET scanner to determine whether modifications to the NEMA NU-2 SF protocol are needed for the characterisation of scatter in such scanners. In addition, we evaluate the impact of patient body mass index (BMI) on SF in a LAFOV scanner. The Siemens Biograph mCT and a typical LAFOV PET scanner were modelled in GATE. Monte Carlo simulations were performed to validate the mCT scanner model against published experimental results. SF was estimated using a modified NEMA NU-2 protocol with variable radial offsets on both scanners and compared to ground truth SF measurements obtained with a uniform-activity cylindrical phantom. Correlation between BMI and SF in the LAFOV scanner was evaluated by simulating anthropomorphic phantoms with different BMIs and realistic 18F-FDG distributions, together with uniformly-filled 200cm long cylindrical phantoms with equivalent effective diameters. The optimal offset was found to be either 60mm or 80mm, depending on the chosen optimality metric. We conclude that modifications to NEMA NU-2 are required for accurate SF characterisation in whole-body and LAFOV scanners. Finally, SF in anthropomorphic phantoms with realistic tissue concentrations of 18F-FDG was found to be strongly correlated with SF in an equivalent-volume cylindrical phantom for the LAFOV PET scanner; BMI was also found to strongly positively correlate with the SF.
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Affiliation(s)
- Amir Ghabrial
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva, Switzerland; University of Technology Sydney, Ultimo NSW 2007, Australia
| | | | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva, Switzerland; Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, 9700 RB Groningen, The Netherlands; Department of Nuclear Medicine, University of Southern Denmark, DK-500 Odense, Denmark
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18
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Chen S, Gu Y, Yu H, Chen X, Cao T, Hu L, Shi H. NEMA NU2-2012 performance measurements of the United Imaging uPMR790: an integrated PET/MR system. Eur J Nucl Med Mol Imaging 2021; 48:1726-1735. [PMID: 33388972 DOI: 10.1007/s00259-020-05135-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 11/24/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE In this paper, we aimed to evaluate the positron emission tomography (PET) performance of, to the best of our knowledge, the third commercially available whole-body integrated PET/magnetic resonance (MR) system. METHODS The PET system performance was measured following the NEMA standards with and without simultaneous MR operation. PET spatial resolution, sensitivity, scatter fraction, count-rate performance, accuracy of count losses and random corrections, image quality, and time-of-flight (TOF) resolution were quantitatively evaluated. Clinical scans were acquired at the PET/MR system and compared with images acquired at a PET/CT with the same digital detector technology. RESULTS Measurement results of essential PET performance were reported in the form of MR idle (MR pulsing). The axial, radial, and tangential spatial resolutions were measured as 2.72 mm (2.73 mm), 2.86 mm (2.85 mm), and 2.81 mm (2.82 mm) FWHM, respectively, at 1 cm radial offset. The NECR peak was measured as 129.2 kcps (129.5 kcps) at 14.7 kBq mL-1 (14.2 kBq mL-1). The scatter fraction at NECR peak was 37.9% (36.5%), and the maximum slice error below NECR was 4.1% (4.5%). Contrast recovery coefficients ranged from 51.8% (52.3%) for 10 mm hot sphere to 87.3% (87.2%) for 37 mm cold sphere. TOF resolution at 5.3 kBq mL-1 was measured at 535 ps (540 ps). With point source, TOF was measured to be 474 ps (485 ps). Clinical scans revealed similar image quality from the PET/MR and the comparative PET/CT system. CONCLUSION The PET performance of the newly introduced integrated PET/MR system is not significantly affected by the simultaneous operation of an MR sequence (2-point DIXON sequence). Measurement results demonstrate comparable performance with other state-of-the-art PET/MR systems. The clinical benefits of high spatial resolution and long axial coverage remain to be further evaluated in specific clinical imaging applications.
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Affiliation(s)
- Shuguang Chen
- Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai, 200032, China.,Institute of Nuclear Medicine, Fudan University, Shanghai, China
| | - Yushen Gu
- Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai, 200032, China.,Institute of Nuclear Medicine, Fudan University, Shanghai, China
| | - Haojun Yu
- Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai, 200032, China.,Institute of Nuclear Medicine, Fudan University, Shanghai, China
| | - Xin Chen
- United Imaging Healthcare Co., Ltd., Shanghai, China
| | - Tuoyu Cao
- United Imaging Healthcare Co., Ltd., Shanghai, China
| | - Lingzhi Hu
- United Imaging Healthcare Co., Ltd., Shanghai, China
| | - Hongcheng Shi
- Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai, 200032, China. .,Institute of Nuclear Medicine, Fudan University, Shanghai, China.
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19
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Surti S, Karp JS. Update on latest advances in time-of-flight PET. Phys Med 2020; 80:251-258. [PMID: 33212421 PMCID: PMC7749844 DOI: 10.1016/j.ejmp.2020.10.031] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/24/2020] [Accepted: 10/29/2020] [Indexed: 11/20/2022] Open
Abstract
This paper provides an update on time-of-flight (TOF) PET with a focus on latest hardware developments leading to current commercial PET/CT instruments. We describe advances in scintillator development, new photosensors and associated electronics readout, and detector designs for utilization in complete systems. Next, we introduce the latest commercial PET/CT scanners based on the aforementioned technologies, and discuss the detector design choices made that are relevant to differences in the system performance. Finally, we end with a discussion of the latest performance benchmarks for improved timing in PET detectors, challenges in scaling this performance to a complete system, and the outlook towards achieving a sub-50 ps coincidence timing resolution (CTR) in a PET detector.
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Affiliation(s)
- Suleman Surti
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Joel S Karp
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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20
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Henrich TJ, Jones T, Beckford-Vera D, Price PM, VanBrocklin HF. Total-Body PET Imaging in Infectious Diseases. PET Clin 2020; 16:89-97. [PMID: 33160926 DOI: 10.1016/j.cpet.2020.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Total-body PET enables high-sensitivity imaging with dramatically improved signal-to-noise ratio. These enhanced performance characteristics allow for decreased PET scanning times acquiring data "total-body wide" and can be leveraged to decrease the amount of radiotracer required, thereby permitting more frequent imaging or longer imaging periods during radiotracer decay. Novel approaches to PET imaging of infectious diseases are emerging, including those that directly visualize pathogens in vivo and characterize concomitant immune responses and inflammation. Efforts to develop these imaging approaches are hampered by challenges of traditional imaging platforms, which may be overcome by novel total-body PET strategies.
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Affiliation(s)
- Timothy J Henrich
- Division of Experimental Medicine, University of California San Francisco, 1001 Potrero Avenue, Building 3, Room 525A, San Francisco, CA 94110, USA.
| | - Terry Jones
- Department of Radiology, University of California Davis Medical Center, Sacramento, CA, USA
| | - Denis Beckford-Vera
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | | | - Henry F VanBrocklin
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
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21
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Johnson GB, Harms HJ, Johnson DR, Jacobson MS. PET Imaging of Tumor Perfusion: A Potential Cancer Biomarker? Semin Nucl Med 2020; 50:549-561. [PMID: 33059824 DOI: 10.1053/j.semnuclmed.2020.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Perfusion, as measured by imaging, is considered a standard of care biomarker for the evaluation of many tumors. Measurements of tumor perfusion may be used in a number of ways, including improving the visual detection of lesions, differentiating malignant from benign findings, assessing aggressiveness of tumors, identifying ischemia and by extension hypoxia within tumors, and assessing treatment response. While most clinical perfusion imaging is currently performed with CT or MR, a number of methods for PET imaging of tumor perfusion have been described. The inert PET radiotracer 15O-water PET represents the recognized gold standard for absolute quantification of tissue perfusion in both normal tissue and a variety of pathological conditions including cancer. Other cancer PET perfusion imaging strategies include the use of radiotracers with high first-pass uptake, analogous to those used in cardiac perfusion PET. This strategy produces more visually pleasing high-contrast images that provide relative rather than absolute perfusion quantification. Lastly, multiple timepoint imaging of PET tracers such as 18F-FDG, are not specifically optimized for perfusion, but have advantages related to availability, convenience, and reimbursement. Multiple obstacles have thus far blocked the routine use of PET imaging for tumor perfusion, including tracer production and distribution, image processing, patient body coverage, clinical validation, regulatory approval and reimbursement, and finally feasible clinical workflows. Fortunately, these obstacles are being overcome, especially within larger imaging centers, opening the door for PET imaging of tumor perfusion to become standard clinical practice. In the foreseeable future, it is possible that whole-body PET perfusion imaging with 15O-water will be able to be performed in a single imaging session concurrent with standard PET imaging techniques such as 18F-FDG-PET. This approach could establish an efficient clinical workflow. The resultant ability to measure absolute tumor blood flow in combination with glycolysis will provide important complementary information to inform prognosis and clinical decisions.
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Affiliation(s)
- Geoffrey B Johnson
- Department of Radiology, Mayo Clinic, Rochester, MNDepartment of Neurology, Mayo Clinic, Rochester, MN; Department of Immunology, Mayo Clinic, Rochester, MN.
| | - Hendrik J Harms
- Department of Surgical Sciences, Nuclear Medicine, PET and Radiology, Uppsala University, Uppsala Sweden
| | - Derek R Johnson
- Department of Radiology, Mayo Clinic, Rochester, MNDepartment of Neurology, Mayo Clinic, Rochester, MN
| | - Mark S Jacobson
- Department of Radiology, Mayo Clinic, Rochester, MNDepartment of Neurology, Mayo Clinic, Rochester, MN
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Evaluation of Various Scintillator Materials in Radiation Detector Design for Positron Emission Tomography (PET). CRYSTALS 2020. [DOI: 10.3390/cryst10100869] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The performance of radiation detectors used in positron-emission tomography (PET) is determined by the intrinsic properties of the scintillators, the geometry and surface treatment of the scintillator crystals and the electrical and optical characteristics of the photosensors. Experimental studies were performed to assess the timing resolution and energy resolution of detectors constructed with samples of different scintillator materials (LaBr3, CeBr3, LFS, LSO, LYSO: Ce, Ca and GAGG) that were fabricated into different shapes with various surface treatments. The saturation correction of SiPMs was applied for tested detectors based on a Tracepro simulation. Overall, we tested 28 pairs of different forms of scintillators to determine the one with the best CTR and light output. Two common high-performance silicon photomultipliers (SiPMs) provided by SensL (J-series, 6 mm) or AdvanSiD (NUV, 6 mm) were used for photodetectors. The PET detector constructed with 6 mm CeBr3 cubes achieved the best CTR with a FWHM of 74 ps. The 4 mm co-doped LYSO: Ce, Ca pyramid crystals achieved 88.1 ps FWHM CTR. The 2 mm, 4 mm and 6 mm 0.2% Ce, 0.1% Ca co-doped LYSO cubes achieved 95.6 ps, 106 ps and 129 ps FWHM CTR, respectively. The scintillator crystals with unpolished surfaces had better timing than those with polished surfaces. The timing resolution was also improved by using certain geometric factors, such as a pyramid shape, to improve light transportation in the scintillator crystals.
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Abstract
In the light of ever-increasing demands for PET scanner with better resolvability, higher sensitivity and wide accessibility for noninvasive screening of small structures and physiological processes in laboratory rodents, several dedicated PET scanners were developed and evaluated. Understanding conceptual design constraints pros and cons of different configurations and impact of the major components will be helpful to further establish the crucial role of these miniaturized systems in a broad spectrum of modern research. Hence, a comprehensive review of preclinical PET scanners developed till early 2020 with particular emphasis on innovations in instrumentation and geometrical designs is provided.
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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
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211, Switzerland; Geneva University Neurocenter, Geneva University, Geneva CH-1205, Switzerland; Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, Netherlands; Department of Nuclear Medicine, University of Southern Denmark, Odense 500, 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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Highly multiplexed SiPM signal readout for brain-dedicated TOF-DOI PET detectors. Phys Med 2019; 68:117-123. [DOI: 10.1016/j.ejmp.2019.11.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/12/2019] [Accepted: 11/18/2019] [Indexed: 12/22/2022] Open
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Berg E, Gill H, Marik J, Ogasawara A, Williams S, van Dongen G, Vugts D, Cherry SR, Tarantal AF. Total-Body PET and Highly Stable Chelators Together Enable Meaningful 89Zr-Antibody PET Studies up to 30 Days After Injection. J Nucl Med 2019; 61:453-460. [PMID: 31562219 DOI: 10.2967/jnumed.119.230961] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 08/29/2019] [Indexed: 01/30/2023] Open
Abstract
The use of 89Zr-antibody PET imaging to measure antibody biodistribution and tissue pharmacokinetics is well established, but current PET systems lack the sensitivity needed to study 89Zr-labeled antibodies beyond 2-3 isotope half-lives (7-10 d), after which a poor signal-to-noise ratio is problematic. However, studies across many weeks are desirable to better match antibody circulation half-life in human and nonhuman primates. These studies investigated the technical feasibility of using the primate mini-EXPLORER PET scanner, making use of its high sensitivity and 45-cm axial field of view, for total-body imaging of 89Zr-labeled antibodies in rhesus monkeys up to 30 d after injection. Methods: A humanized monoclonal IgG antibody against the herpes simplex viral protein glycoprotein D (gD) was radiolabeled with 89Zr via 1 of 4 chelator-linker combinations (benzyl isothiocyanate-DFO [DFO-Bz-NCS], where DFO is desferrioxamine B; DFO-squaramide; DFO*-Bz-NCS, where DFO* is desferrioxamine*; and DFO*-squaramide). The pharmacokinetics associated with these 4 chelator-linker combinations were compared in 12 healthy young male rhesus monkeys (∼1-2 y old, ∼3 ± 1 kg). Each animal was initially injected intravenously with unlabeled antibody in a peripheral vessel in the right arm (10 mg/kg, providing therapeutic-level antibody concentrations), immediately followed by approximately 40 MBq of one of the 89Zr-labeled antibodies injected intravenously in a peripheral vessel in the left arm. All animals were imaged 6 times over a period of 30 d, with an initial 60-min dynamic scan on day 0 (day of injection) followed by static scans of 30-45 min on approximately days 3, 7, 14, 21, and 30, with all acquired using a single bed position and images reconstructed using time-of-flight list-mode ordered-subsets expectation maximization. Activity concentrations in various organs were extracted from the PET images using manually defined regions of interest. Results: Excellent image quality was obtained, capturing the initial distribution phase in the whole-body scan; later time points showed residual 89Zr mainly in the liver. Even at 30 d after injection, representing approximately 9 half-lives of 89Zr and with a total residual activity of only 20-40 kBq in the animal, the image quality was sufficient to readily identify activity in the liver, kidneys, and upper and lower limb joints. Significant differences were noted in late time point liver uptake, bone uptake, and whole-body clearance between chelator-linker types, whereas little variation (±10%) was observed within each type. Conclusion: These studies demonstrate the ability to image 89Zr-radiolabeled antibodies up to 30 d after injection while maintaining satisfactory image quality, as provided by the primate mini-EXPLORER with high sensitivity and long axial field of view. Quantification demonstrated potentially important differences in the behavior of the 4 chelators. This finding supports further investigation.
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Affiliation(s)
- Eric Berg
- Department of Biomedical Engineering, University of California-Davis, Davis, California
| | - Herman Gill
- Department of Biomedical Imaging, Genentech Inc., South San Francisco, California
| | - Jan Marik
- Department of Biomedical Imaging, Genentech Inc., South San Francisco, California
| | - Annie Ogasawara
- Department of Biomedical Imaging, Genentech Inc., South San Francisco, California
| | - Simon Williams
- Department of Biomedical Imaging, Genentech Inc., South San Francisco, California
| | - Guus van Dongen
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, VU University, Amsterdam, The Netherlands
| | - Daniëlle Vugts
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, VU University, Amsterdam, The Netherlands
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California-Davis, Davis, California.,Department of Radiology, School of Medicine, University of California-Davis, Davis, California; and
| | - Alice F Tarantal
- Department of Pediatrics and Department of Cell Biology and Human Anatomy, School of Medicine, and California National Primate Research Center, University of California-Davis, Davis, California
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Henrich TJ, Hsue PY, VanBrocklin H. Seeing Is Believing: Nuclear Imaging of HIV Persistence. Front Immunol 2019; 10:2077. [PMID: 31572355 PMCID: PMC6751256 DOI: 10.3389/fimmu.2019.02077] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 08/16/2019] [Indexed: 12/19/2022] Open
Abstract
A major obstacle to HIV eradication is the presence of infected cells that persist despite suppressive antiretroviral therapy (ART). HIV largely resides outside of the peripheral circulation, and thus, numerous anatomical and lymphoid compartments that have the capacity to harbor HIV are inaccessible to routine sampling. As a result, there is a limited understanding of the tissue burden of HIV infection or anatomical distribution of HIV transcriptional and translational activity. Novel, non-invasive, in vivo methods are urgently needed to address this fundamental gap in knowledge. In this review, we discuss past and current nuclear imaging approaches that have been applied to HIV infection with an emphasis on current strategies to implement positron emission tomography (PET)-based imaging to directly visualize and characterize whole-body HIV burden. These imaging approaches have various limitations, such as the potential for limited PET sensitivity and specificity in the setting of ART suppression or low viral burden. However, recent advances in high-sensitivity, total-body PET imaging platforms and development of new radiotracer technologies that may enhance anatomical penetration of target-specific tracer molecules are discussed. Potential strategies to image non-viral markers of HIV tissue burden or focal immune perturbation are also addressed. Overall, emerging nuclear imaging techniques and platforms may play an important role in the development of novel therapeutic and HIV reservoir eradication strategies.
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Affiliation(s)
- Timothy J Henrich
- Division of Experimental Medicine, Department of Medicine, University of San Francisco, San Francisco, CA, United States
| | - Priscilla Y Hsue
- Division of Cardiology, Department of Medicine, University of San Francisco, San Francisco, CA, United States
| | - Henry VanBrocklin
- Radiopharmaceutical Research Program, Center for Molecular and Functional Imaging, University of San Francisco, San Francisco, CA, United States
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Zhang X, Xie Z, Berg E, Judenhofer MS, Liu W, Xu T, Ding Y, Lv Y, Dong Y, Deng Z, Tang S, Shi H, Hu P, Chen S, Bao J, Li H, Zhou J, Wang G, Cherry SR, Badawi RD, Qi J. Total-Body Dynamic Reconstruction and Parametric Imaging on the uEXPLORER. J Nucl Med 2019; 61:285-291. [DOI: 10.2967/jnumed.119.230565] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 07/06/2019] [Indexed: 01/02/2023] Open
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30
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Badawi RD, Shi H, Hu P, Chen S, Xu T, Price PM, Ding Y, Spencer BA, Nardo L, Liu W, Bao J, Jones T, Li H, Cherry SR. First Human Imaging Studies with the EXPLORER Total-Body PET Scanner. J Nucl Med 2019; 60:299-303. [PMID: 30733314 DOI: 10.2967/jnumed.119.226498] [Citation(s) in RCA: 404] [Impact Index Per Article: 80.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 12/24/2022] Open
Abstract
Within the EXPLORER Consortium, the construction of the world's first total-body PET/CT scanner has recently been completed. The 194-cm axial field of view of the EXPLORER PET/CT scanner is sufficient to cover, for the first time, the entire human adult body in a single acquisition in more than 99% of the population and allows total-body pharmacokinetic studies with frame durations as short as 1 s. The large increase in sensitivity arising from total-body coverage as well as increased solid angle for detection at any point within the body allows whole-body 18F-FDG PET studies to be acquired with unprecedented count density, improving the signal-to-noise ratio of the resulting images. Alternatively, the sensitivity gain can be used to acquire diagnostic PET images with very small amounts of activity in the field of view (25 MBq, 0.7 mCi or less), with very short acquisition times (∼1 min or less) or at later time points after the tracer's administration. We report here on the first human imaging studies on the EXPLORER scanner using a range of different protocols that provide initial evidence in support of these claims. These case studies provide the foundation for future carefully controlled trials to quantitatively evaluate the improvements possible through total-body PET imaging.
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Affiliation(s)
- Ramsey D Badawi
- Department of Radiology, University of California Davis Medical Center, Sacramento, California .,Department of Biomedical Engineering, University of California, Davis, California
| | - Hongcheng Shi
- Department of Nuclear Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Pengcheng Hu
- Department of Nuclear Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Shuguang Chen
- Department of Nuclear Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Tianyi Xu
- United Imaging Healthcare, Shanghai, China; and
| | - Patricia M Price
- Department of Surgery and Cancer, Imperial College, London, United Kingdom
| | - Yu Ding
- United Imaging Healthcare, Shanghai, China; and
| | - Benjamin A Spencer
- Department of Radiology, University of California Davis Medical Center, Sacramento, California
| | - Lorenzo Nardo
- Department of Radiology, University of California Davis Medical Center, Sacramento, California
| | - Weiping Liu
- United Imaging Healthcare, Shanghai, China; and
| | - Jun Bao
- United Imaging Healthcare, Shanghai, China; and
| | - Terry Jones
- Department of Radiology, University of California Davis Medical Center, Sacramento, California
| | - Hongdi Li
- United Imaging Healthcare, Shanghai, China; and
| | - Simon R Cherry
- Department of Radiology, University of California Davis Medical Center, Sacramento, California.,Department of Biomedical Engineering, University of California, Davis, California
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