Development of a full-ring “add-on PET” prototype: A head coil with DOI-PET detectors for integrated PET/MRI

Nishikido, Fumihiko; Fujiwara, Masaki; Tashima, Hideaki; Akram, Md. Shahadat Hossain; Suga, Mikio; Obata, Takayuki; Yamaya, Taiga

doi:10.1016/j.nima.2017.05.006

Cited by 24 publications

(24 citation statements)

References 21 publications

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“…Subsequently, the LYSO crystal dimensions were reduced to 2 • 2 • 5 mm 3 , and they were arranged in 4 layers of 19 • 6 arrays ( Fig. 5C) (57). The PET detector modules were mounted between the elements of a 3-T MRI birdcage coil to evaluate their performance.…”

Section: Conventional Scanner Geometry Devicesmentioning

confidence: 99%

“…The spatial resolution ranged from 2.3 mm at the center of the FOV to 3.5 mm offcenter. The sensitivity was not estimated given the relatively limited extent of the axial FOV (1.2 cm), which would not be sufficient for actual brain studies, as acknowledged by the authors (57). A different approach to minimizing the interference between the two modalities was proposed by researchers from Stanford.…”

Section: Conventional Scanner Geometry Devicesmentioning

confidence: 99%

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Development of Dedicated Brain PET Imaging Devices: Recent Advances and Future Perspectives

Catana

2019

J Nucl Med

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Whole-body PET scanners are not optimized for imaging small structures in the human brain. Several PET devices specifically designed for this task have been proposed either for stand-alone operation or as MR-compatible inserts. The main distinctive features of some of the most recent concepts and their performance characteristics, with a focus on spatial resolution and sensitivity, are reviewed. The tradeoffs between the various performance characteristics, desired capabilities, and cost that need to be considered when designing a dedicated brain scanner are presented. Finally, the aspirational goals for future-generation scanners, some of the factors that have contributed to the current status, and how recent advances may affect future developments in dedicated brain PET instrumentation are briefly discussed.

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Section: Conventional Scanner Geometry Devicesmentioning

confidence: 99%

Section: Conventional Scanner Geometry Devicesmentioning

confidence: 99%

Development of Dedicated Brain PET Imaging Devices: Recent Advances and Future Perspectives

Catana

2019

J Nucl Med

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“…7,15 Some studies have recently reported on PET/MRS imaging as well. [16][17][18] Although the whole-body PET/MRI system became available in 2010, 9 recent growing interest in the development of a low-cost PET insert (such as a brain PET) for existing MRI systems [19][20][21][22][23][24] has created a potentially dominant new research field in multimodal medical imaging research. However, in all these PET insert developments, a singlechannel volume radiofrequency (RF) coil (e.g., birdcage RF coil) was implemented as a transmitter.…”

Section: Major Papermentioning

confidence: 99%

“…[25][26][27][28][29][30][31] Conventionally, detectors and front-end electronics of a PET insert are RF shielded to avoid electromagnetic (EM) interference between the two systems. [19][20][21][22][23][24] In this study, we developed a novel design of a microstrip transmission line RF coil [27][28][29][30] that combines the RF shield of a PET detector module with a microstrip conductor that acts as a transmission line coil. The conventional microstrip coil consists of two metal conductors (one is a microstrip conductor, and the other is a ground conductor) and a dielectric between the two conductors.…”

Section: Major Papermentioning

confidence: 99%

“…The reduction in RF shield materials is important for a reduced gradient eddy current effect, 32 which is one of the major design challenges for PET insert researchers. [19][20][21][22][23][24][25] Moreover, the combined PET-microstrip coil modality should be a compact single multimodal device that can be mounted with ease on an existing patient bed of an MRI scanner similar to the extremity RF coils, such as the head RF coil. Since the combined system is a single PET-coil module with minimal coil components, it should have minimal photon attenuation in the RF coil (e.g., only microstrip conductor) and would provide strong mechanical support.…”

Section: Major Papermentioning

confidence: 99%

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Microstrip Transmission Line RF Coil for a PET/MRI Insert

2020

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We proposed and developed a new microstrip transmission line radiofrequency (RF) coil for a positron emission tomography (PET) insert for MRI, which has low electrical interactions with PET shield boxes. We performed imaging experiments using a single-channel and a four-channel proposed RF coils for proof-of-concept. Methods: A conventional microstrip coil consists of a microstrip conductor, a ground conductor, and a dielectric between the two conductors. We proposed a microstrip coil for the PET insert that replaced the conventional single-layer ground conductor with the RF shield of the PET insert. A dielectric material, which could otherwise attenuate gamma photons radiated from the PET imaging tracer, was not used. As proof-of-concept, we compared conventional and the proposed single-channel coils. To study multichannel performance, we further developed a four-channel proposed RF coil. Since the MRI system had a singlechannel transmission port, an interfacing four-way RF power division circuit was designed. The coils were implemented as both RF transmitters and receivers in a cylindrical frame of diameter 150 mm. Coil bench performances were tested with a network analyzer (Rohde & Schwarz, Germany), and a homogeneous phantom study was conducted for gradient echo imaging and RF field (B 1) mapping in a 3T clinical system (Verio, Siemens, Erlangen, Germany). Results: For all coils, the power reflection coefficient was below −30 dB, and the transmission coefficients in the four-channel configuration were near or below −20 dB. The comparative single-channel coil study showed good similarity between the conventional and proposed coils. The gradient echo image of the fourchannel coil showed expected flashing image intensity near the coils and no phase distortion was visible. Transmit B 1 field map resembled the image performance. Conclusion: The proposed PET-microstrip coil performed similarly to the conventional microstrip transmission line coil and is promising for the development of a compact coil-PET system capable of simultaneous PET/MRI analysis with an existing MRI system.

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Study on the radiofrequency transparency of electrically floating and ground PET inserts in a 3 T clinical MRI system

et al. 2022

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Purpose The positron emission tomography (PET) insert for a magnetic resonance imaging (MRI) system that implements the radiofrequency (RF) built‐in body coil of the MRI system as a transmitter is designed to be RF‐transparent, as the coil resides outside the RF‐shielded PET ring. This approach reduces the design complexities (e.g., large PET ring diameter) related to implementing a transmit coil inside the PET ring. However, achieving the required field transmission into the imaging region of interest (ROI) becomes challenging because of the RF shield of the PET insert. In this study, a modularly RF‐shielded PET insert is used to investigate the RF transparency considering two electrical configurations of the RF shield, namely the electrical floating and ground configurations. The purpose is to find the differences, advantages and disadvantages of these two configurations. Methods Eight copper‐shielded PET detector modules (intermodular gap: 3 mm) were oriented cylindrically with an inner diameter of 234 mm. Each PET module included four‐layer Lutetium‐yttrium oxyorthosilicate scintillation crystal blocks and front‐end readout electronics. RF‐shielded twisted‐pair cables were used to connect the front‐end electronics with the power sources and PET data acquisition systems located outside the MRI room. In the ground configuration, both the detector and cable shields were connected to the RF ground of the MRI system. In the floating configuration, only the RF shields of the PET modules were isolated from the RF ground. Experiments were conducted using two cylindrical homogeneous phantoms in a 3 T clinical MRI system, in which the built‐in body RF coil (a cylindrical volume coil of diameter 700 mm and length 540 mm) was implemented as a transceiver. Results For both PET configurations, the RF and MR imaging performances were lower than those for the MRI‐only case, and the MRI system provided specific absorption ratio (SAR) values that were almost double. The RF homogeneity and field strength, and the signal‐to‐noise ratio (SNR) of the MR images were mostly higher for the floating PET configuration than they were for the ground PET configuration. However, for a shorter axial field‐of‐view (FOV) of 125 mm, both configurations offered almost the same performance with high RF homogeneities (e.g., 76 ± 10%). Moreover, for both PET configurations, 56 ± 6% larger RF pulse amplitudes were required for MR imaging purposes. The increased power is mostly absorbed in the conductive shields in the form of shielding RF eddy currents; as a result, the SAR values only in the phantoms were estimated to be close to the MRI‐only values. Conclusions The floating PET configuration showed higher RF transparency under all experimental setups. For a relatively short axial FOV of 125 mm, the ground configuration also performed well which indicated that an RF‐penetrable PET insert with the conventional design (e.g., the ground configuration) might also become possible. However, some design modifications (e.g., a wider intermodular ...

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Development of a full-ring “add-on PET” prototype: A head coil with DOI-PET detectors for integrated PET/MRI

Cited by 24 publications

References 21 publications

Development of Dedicated Brain PET Imaging Devices: Recent Advances and Future Perspectives

Development of Dedicated Brain PET Imaging Devices: Recent Advances and Future Perspectives

Microstrip Transmission Line RF Coil for a PET/MRI Insert

Study on the radiofrequency transparency of electrically floating and ground PET inserts in a 3 T clinical MRI system

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