First Results From a High-Resolution Small Animal SiPM PET Insert for PET/MR Imaging at 7T

Goertzen, Andrew L.; Stortz, Greg; Thiessen, Jonathan D.; Bishop, D.; Khan, Muhammad Salman; Kozłowski, Piotr; Retière, F.; Schellenberg, Graham; Shams, Ehsan; Sossi, Vesna; Thompson, Christopher J.

doi:10.1109/tns.2016.2576963

Cited by 47 publications

(27 citation statements)

References 30 publications

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“…Simultaneous PET/MRI studies were facilitated by using a NuPET™ PET imaging system (Cubresa, Inc., Winnepeg, MB, Canada) and a 7T Biospec MR imaging system (Bruker Biospec, Inc., Billerica, MA) [21]. A cylindrical, quadrature MR transceiver volume coil (Bruker Biospec, Inc.) with a 35 mm inner diameter and 55 mm outer diameter was placed inside a 5-mm-thick plastic sleeve, which was then placed in a cylindrical NuPET™ detector that had a 60 mm inner diameter and a 114 mm outer diameter.…”

Section: Methodsmentioning

confidence: 99%

Preliminary Results that Assess Metformin Treatment in a Preclinical Model of Pancreatic Cancer Using Simultaneous [18F]FDG PET and acidoCEST MRI

2018

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Purpose We sought to determine if the synergy between evaluations of glucose uptake in tumors and extracellular tumor acidosis measured with simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) can improve longitudinal evaluations of the response to metformin treatment. Procedures A standard 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) PET protocol that evaluates glucose uptake in tumors, and a standard acidoCEST MRI protocol that measures extracellular pH (pHe) in tumors, were simultaneously performed to assess eight vehicle-treated (control) mice and eight metformin-treated mice 1 day before treatment, 1 day after initiating daily treatment with metformin, and 7 days after initiating treatment. Longitudinal changes in SUVmax and extracellular pH (pHe) were evaluated for each treatment group, and differences in SUVmax and pHe between metformin-treated and control groups were also evaluated. Results MRI acquisition protocols had little effect on the PET count rate, and the PET instrumentation had little effect on image contrast during acidoCEST MRI, verifying that [18F]FDG PET and acidoCEST MRI can be performed simultaneously. The average SUVmax of the tumor model had a significant decrease after 7 days of treatment with metformin, as expected. The average tumor pHe decreased after 7 days of metformin treatment, which reflected the inhibition of the consumption of cytosolic lactic acid caused by metformin. However, the average SUVmax of the tumor model was not significantly different between the metformin-treated and control groups after 7 days of treatment, and average pHe was also not significantly different between these groups. For comparison, the combination of average SUVmax and pHe measurements significantly differed between the treatment group and control group on Day 7. Conclusions [18F]FDG PET and acidoCEST MRI studies can be performed simultaneously. The synergistic combination of assessing glucose uptake and tumor acidosis can improve differentiation of a drug-treated group from a control group during drug treatment of a tumor model.

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Section: Methodsmentioning

confidence: 99%

Preliminary Results that Assess Metformin Treatment in a Preclinical Model of Pancreatic Cancer Using Simultaneous [18F]FDG PET and acidoCEST MRI

2018

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“…The overall energy resolution of the system was about 12.4% with a mean peak to valley ratio of 43.8 at 25°C temperature and 28 V bias voltage, which is better than the Inveon (14.6%), NanoPET(19%), LabPET (25%) and Argus (26%) . Moreover, it is slightly better than recently designed LYSO/SiPM‐based systems, such as MRS‐PET (14.6%), MADPET4 (13.7%), RAYCAN (15%), Hyperion (12.7%) and scanners reported by Lee et al (13.2%), Ko et al (14.2%) and Goertzen et al (12.5%) but lower than the β‐cube PET scanner (12%) …”

Section: Discussionmentioning

confidence: 69%

NEMA NU‐4 2008 performance evaluation of Xtrim‐PET: A prototype SiPM‐based preclinical scanner

et al. 2019

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Purpose: Xtrim-PET is a newly designed Silicon Photomultipliers (SiPMs)-based prototype PET scanner dedicated for small laboratory animal imaging. We present the performance evaluation of the Xtrim-PET scanner following NEMA NU-4 2008 standards to help optimizing scanning protocols which can be achieved through standard and reliable system performance characterization. Methods: The performance assessment was conducted according to the National Electrical Manufacturers Association (NEMA) NU-4 2008 standards in terms of spatial resolution, sensitivity, counting rate performance, scatter fraction and image quality. The in vivo imaging capability of the scanner is also showcased through scanning a normal mouse injected with 18 F-FDG. Furthermore, the performance characteristics of the developed scanner are compared with commercially available systems and current prototypes. Results: The volumetric spatial resolution at 5 mm radial offset from the central axis of the scanner is 6.81 µl, whereas a peak absolute sensitivity of 2.99% was achieved using a 250-650 keV energy window and a 10 ns timing window. The peak noise-equivalent count rate (NECR) using a mouselike phantom is 113.18 kcps at 0.34 KBq/cc with 12.5% scatter fraction, whereas the NECR peaked at 82.76 kcps for an activity concentration level of 0.048 KBq/cc with a scatter fraction of 25.8% for rat-like phantom. An excellent uniformity (3.8%) was obtained using NEMA image quality phantom. Recovery coefficients of 90%, 86%, 68%, 40% and 12% were calculated for rod diameters of 5, 4, 3, 2 and 1 mm, respectively. Spill-over ratios for air-filled and water-filled chambers were 35% and 25% without applying any correction for attenuation and Compton scattering effects. Conclusion: Our findings revealed that beyond compactness, lightweight, easy installation and good energy resolution, the Xtrim-PET prototype presents a reasonable performance making it suitable for preclinical molecular imaging-based research.

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“…The insert approach can in principle significantly lower the above-mentioned cost barriers for an existing MRI site to achieve simultaneous PET/MRI as it avoids the expensive integration and installation of both PET and MRI sub-systems. Several PET insert systems for PET/MRI have been developed for proof-of-concept [25], [26], imaging small animals [27]–[36] and human brains [37]–[40]. A separate bird-cage radio-frequency (RF) transceiver coil is often placed inside the PET ring to generate and receive RF fields as the Faraday cages used in these PET insert systems block the RF fields from the MRI system.…”

Section: Introductionmentioning

confidence: 99%

Performance Study of a Radio-Frequency Field-Penetrable PET Insert for Simultaneous PET/MRI

Chang

Lee

Grant

et al. 2018

IEEE Trans. Radiat. Plasma Med. Sci.

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Hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) has risen to the cutting edge of medical imaging technology as it allows simultaneous acquisition of structural, functional and molecular information of the patient. A PET insert that can be installed into existing MR systems can in principle reduce the cost barriers for an existing MR site to achieve simultaneous PET/MRI compared to procuring an integrated PET+MRI system. The PET insert systems developed so far for PET/MRI require the RF transmitter coil to reside inside the PET ring as those PET inserts block the RF fields from the MRI system. Here we report for the first time on the performance of a full-ring brain-sized “RF-penetrable” PET insert we have recently completed. This insert allows the RF fields generated by the built-in body coil to penetrate the PET ring. The PET insert comprises a ring of 16 detector modules employing electro-optical coupled signal transmission and a multiplexing framework based on compressed sensing. Energy resolution, coincidence timing resolution (CTR), photopeak position, and coincidence count rate were acquired outside and inside a 3-Tesla MRI system under simultaneous acquisition to evaluate the impact of MRI on the PET performance. Coincidence count rate performance was evaluated by acquiring a cylinder source with high initial activity decaying over time. Tomographic imaging of two phantoms, a custom 6.5-cm diameter resolution phantom with hot rods of four different sizes (2.8 mm, 3.2 mm, 4.2 mm, and 5.2 mm diameter) and a 3D Hoffman brain phantom, were performed to evaluate the imaging capability of the PET insert. The energy resolution at 511 keV and CTR acquired by the PET insert were 16.2±0.1% and 5.3±0.1 ns FWHM, respectively, and remained stable during MRI operation except when the EPI sequence was applied. The PET system starts to show saturation in coincidence count rate at 2.76 million photon counts per second. Most of the 2.8-mm diameter hot rods and main features of the 3D Hoffman brain phantom were resolved by the PET insert, demonstrating its high spatial resolution and capability to image a complex tracer distribution mimicking that seen in the human brain.

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First Results From a High-Resolution Small Animal SiPM PET Insert for PET/MR Imaging at 7T

Cited by 47 publications

References 30 publications

Preliminary Results that Assess Metformin Treatment in a Preclinical Model of Pancreatic Cancer Using Simultaneous [18F]FDG PET and acidoCEST MRI

Preliminary Results that Assess Metformin Treatment in a Preclinical Model of Pancreatic Cancer Using Simultaneous [18F]FDG PET and acidoCEST MRI

NEMA NU‐4 2008 performance evaluation of Xtrim‐PET: A prototype SiPM‐based preclinical scanner

Performance Study of a Radio-Frequency Field-Penetrable PET Insert for Simultaneous PET/MRI

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