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Akram MSH, Levin CS, Nishikido F, Takyu S, Obata T, Yamaya T. Study on the radiofrequency transparency of partial-ring oval-shaped prototype PET inserts in a 3 T clinical MRI system. Radiol Phys Technol 2024; 17:60-70. [PMID: 37874462 DOI: 10.1007/s12194-023-00747-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/27/2023] [Accepted: 10/02/2023] [Indexed: 10/25/2023]
Abstract
The purpose of this study is to evaluate the RF field responses of partial-ring RF-shielded oval-shaped positron emission tomography (PET) inserts that are used in combination with an MRI body RF coil. Partial-ring PET insert is particularly suitable for interventional investigation (e.g., trimodal PET/MRI/ultrasound imaging) and intraoperative (e.g., robotic surgery) PET/MRI studies. In this study, we used electrically floating Faraday RF shield cages to construct different partial-ring configurations of oval and cylindrical PET inserts and performed experiments on the RF field, spin echo and gradient echo images for a homogeneous phantom in a 3 T clinical MRI system. For each geometry, partial-ring configurations were studied by removing an opposing pair or a single shield cage from different positions of the PET ring. Compared to the MRI-only case, reduction in mean RF homogeneity, flip angle, and SNR for the detector opening in the first and third quadrants was approximately 13%, 15%, and 43%, respectively, whereas the values were 8%, 23%, and 48%, respectively, for the detector openings in the second and fourth quadrants. The RF field distribution also varied for different partial-ring configurations. It can be concluded that the field penetration was high for the detector openings in the first and third quadrants of both the inserts.
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Affiliation(s)
- Md Shahadat Hossain Akram
- Department of Advanced Nuclear Medicine Sciences, Institute of Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage, Chiba, 263-8555, Japan.
| | - Craig S Levin
- Department of Radiology, School of Medicine, Stanford University, Stanford, CA, 94305-5128, USA
| | - Fumihiko Nishikido
- Department of Advanced Nuclear Medicine Sciences, Institute of Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage, Chiba, 263-8555, Japan
| | - Sodai Takyu
- Department of Advanced Nuclear Medicine Sciences, Institute of Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage, Chiba, 263-8555, Japan
| | - Takayuki Obata
- Department of Applied MRI Research, Institute of Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), Anagawa 4-9-1, Inage, Chiba, 263-8555, Japan
| | - Taiga Yamaya
- Department of Advanced Nuclear Medicine Sciences, Institute of Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage, Chiba, 263-8555, Japan
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Sanaat A, Amini M, Arabi H, Zaidi H. The quest for multifunctional and dedicated PET instrumentation with irregular geometries. Ann Nucl Med 2024; 38:31-70. [PMID: 37952197 PMCID: PMC10766666 DOI: 10.1007/s12149-023-01881-6] [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: 08/01/2023] [Accepted: 10/09/2023] [Indexed: 11/14/2023]
Abstract
We focus on reviewing state-of-the-art developments of dedicated PET scanners with irregular geometries and the potential of different aspects of multifunctional PET imaging. First, we discuss advances in non-conventional PET detector geometries. Then, we present innovative designs of organ-specific dedicated PET scanners for breast, brain, prostate, and cardiac imaging. We will also review challenges and possible artifacts by image reconstruction algorithms for PET scanners with irregular geometries, such as non-cylindrical and partial angular coverage geometries and how they can be addressed. Then, we attempt to address some open issues about cost/benefits analysis of dedicated PET scanners, how far are the theoretical conceptual designs from the market/clinic, and strategies to reduce fabrication cost without compromising performance.
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Affiliation(s)
- Amirhossein Sanaat
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva, Switzerland
| | - Mehdi Amini
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva, Switzerland
| | - Hossein Arabi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva, Switzerland
| | - 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, 500, Odense, Denmark.
- University Research and Innovation Center, Óbuda University, Budapest, Hungary.
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Akamatsu G, Tashima H, Yoshida E, Iwao Y, Takyu S, Wakizaka H, Takahashi M, Yamaya T. [[PET] 3. The World's First Hemispherical Brain PET System: VRAIN]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2023; 79:200-205. [PMID: 36804812 DOI: 10.6009/jjrt.2023-2161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Affiliation(s)
- Go Akamatsu
- National Institutes for Quantum Science and Technology (QST)
| | - Hideaki Tashima
- National Institutes for Quantum Science and Technology (QST)
| | - Eiji Yoshida
- National Institutes for Quantum Science and Technology (QST)
| | - Yuma Iwao
- National Institutes for Quantum Science and Technology (QST)
| | - Sodai Takyu
- National Institutes for Quantum Science and Technology (QST)
| | | | | | - Taiga Yamaya
- National Institutes for Quantum Science and Technology (QST)
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Akamatsu G, Takahashi M, Tashima H, Iwao Y, Yoshida E, Wakizaka H, Kumagai M, Yamashita T, Yamaya T. Performance evaluation of VRAIN: a brain-dedicated PET with a hemispherical detector arrangement. Phys Med Biol 2022; 67. [PMID: 36317319 DOI: 10.1088/1361-6560/ac9e87] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 10/28/2022] [Indexed: 11/07/2022]
Abstract
Objective.For PET imaging systems, a smaller detector ring enables less intrinsic spatial resolution loss due to the photon non-collinearity effect as well as better balance between production cost and sensitivity, and a hemispherical detector arrangement is more appropriate for brain imaging than a conventional cylindrical arrangement. Therefore, we have developed a brain-dedicated PET system with a hemispherical detector arrangement, which has been commercialized in Japan under the product name of VRAINTM. In this study, we evaluated imaging performance of VRAIN.Approach.The VRAIN used 54 detectors to form the main hemispherical unit and an additional half-ring behind the neck. Each detector was composed of a 12 × 12 array of lutetium fine silicate crystals (4.1 × 4.1 × 10 mm3) and a 12 × 12 array of silicon photomultipliers (4 × 4 mm2active area) with the one-to-one coupling. We evaluated the physical performance of VRAIN according to the NEMA NU 2-2018 standards. Some measurements were modified so as to fit the hemispherical geometry. In addition, we performed18F-FDG imaging in a healthy volunteer.Main results.In the phantom study, the VRAIN showed high resolution for separating 2.2 mm rods, 229 ps TOF resolution and 19% scatter fraction. With the TOF gain for a 20 cm diameter object (an assumed head diameter), the peak noise-equivalent count rate was 144 kcps at 9.8 kBq ml-1and the sensitivity was 25 kcps MBq-1. Overall, the VRAIN provided excellent image quality in phantom and human studies. In the human FDG images, small brain nuclei and gray matter structures were clearly visualized with high contrast and low noise.Significance.We demonstrated the excellent imaging performance of VRAIN, which supported the advantages of the hemispherical detector arrangement.
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Affiliation(s)
- Go Akamatsu
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
| | - Miwako Takahashi
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
| | - Hideaki Tashima
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
| | - Yuma Iwao
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
| | - Eiji Yoshida
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
| | - Hidekatsu Wakizaka
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
| | | | | | - Taiga Yamaya
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
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Mohammadi I, Castro IF, Rahmim A, Veloso JFCA. Motion in nuclear cardiology imaging: types, artifacts, detection and correction techniques. Phys Med Biol 2021; 67. [PMID: 34826826 DOI: 10.1088/1361-6560/ac3dc7] [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: 07/03/2021] [Accepted: 11/26/2021] [Indexed: 11/12/2022]
Abstract
In this paper, the authors review the field of motion detection and correction in nuclear cardiology with single photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging systems. We start with a brief overview of nuclear cardiology applications and description of SPECT and PET imaging systems, then explaining the different types of motion and their related artefacts. Moreover, we classify and describe various techniques for motion detection and correction, discussing their potential advantages including reference to metrics and tasks, particularly towards improvements in image quality and diagnostic performance. In addition, we emphasize limitations encountered in different motion detection and correction methods that may challenge routine clinical applications and diagnostic performance.
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Affiliation(s)
- Iraj Mohammadi
- Department of Physics, University of Aveiro, Aveiro, PORTUGAL
| | - I Filipe Castro
- i3n Physics Department, Universidade de Aveiro, Aveiro, PORTUGAL
| | - Arman Rahmim
- Radiology and Physics, The University of British Columbia, Vancouver, British Columbia, CANADA
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