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Study on the radiofrequency transparency of partial-ring oval-shaped prototype PET inserts in a 3 T clinical MRI system

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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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Authors and Affiliations

  1. 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

    Md Shahadat Hossain Akram, Fumihiko Nishikido, Sodai Takyu & Taiga Yamaya

  2. Department of Radiology, School of Medicine, Stanford University, Stanford, CA, 94305-5128, USA

    Craig S. Levin

  3. 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

    Takayuki Obata

Authors
  1. Md Shahadat Hossain Akram
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  2. Craig S. Levin
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  3. Fumihiko Nishikido
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  4. Sodai Takyu
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  5. Takayuki Obata
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  6. Taiga Yamaya
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Correspondence to Md Shahadat Hossain Akram.

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No approval of research ethics committees was required to accomplish the goals of this study because no human or animal study was conducted in this technical study.

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Akram, M.S.H., Levin, C.S., Nishikido, F. et al. Study on the radiofrequency transparency of partial-ring oval-shaped prototype PET inserts in a 3 T clinical MRI system. Radiol Phys Technol 17, 60–70 (2024). https://doi.org/10.1007/s12194-023-00747-w

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  • DOI: https://doi.org/10.1007/s12194-023-00747-w

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