High-Resolution Silicon Photomultiplier Time-of-Flight Dedicated Head PET System for Clinical Brain Studies

Ishii, Kazunari; Hanaoka, Kohei; Watanabe, Shota; Morimoto-Ishikawa, Daisuke; Yamada, Takahiro; Kaida, Hayato; Yamakawa, Yoshiyuki; Minagawa, Suzuka; Takenouchi, Shiho; Ohtani, A.; Mizuta, Tetsuro

doi:10.2967/jnumed.122.264080

Cited by 9 publications

(5 citation statements)

References 23 publications

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“…It has been considered that conventional WB PET scanners are inadequate to evaluate small brain structures, including brainstem nuclei, because of their relatively poor spatial resolution. Indeed, several reports have described PET-tracer uptake in the brainstem nuclei using head-dedicated PET scanners [ 12 , 13 , 16 ]. For example, Takahashi et al described that FDG uptake in small brainstem nuclei such as the IC, RN, and MRN were more clearly detected by a brain-dedicated PET system with a hemispherical shape than by WB PET [ 12 ].…”

Section: Discussionmentioning

confidence: 99%

Visualization of small brain nuclei with a high-spatial resolution, clinically available whole-body PET scanner

Shinohara,

Ibaraki,

Matsubara

et al. 2023

Ann Nucl Med

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ObjectiveTo verify the visibility of physiological18F-fluorodeoxyglucose (18F-FDG) uptake in nuclei in and around the brainstem by a whole-body (WB) silicon photomultiplier positron emission tomography (SiPM-PET) scanner with point-spread function (PSF) reconstruction using various iteration numbers.MethodsTen healthy subjects (5 men, 5 women; mean age, 56.0 ± 5.0 years) who underwent18F-FDG PET/CT using a WB SiPM-PET scanner and magnetic resonance imaging (MRI) of the brain including a spin-echo three-dimensional sampling perfection with application-optimized contrasts using different flip angle evolutions fluid-attenuated inversion recovery (3D-FLAIR) and a 3D-T1 magnetization-prepared rapid gradient-echo (T1-MPRAGE) images were enrolled. Each acquired PET image was reconstructed using ordered-subset expectation maximization (OSEM) with iteration numbers of 4, 16, 64, and 256 (subset 5 fixed) + time-of-flight (TOF) + PSF. The reconstructed PET images and 3D-FLAIR images for each subject were registered to individual T1-MPRAGE volumes using normalized mutual information criteria. For each MR-coregistered individual PET image, the pattern of FDG uptake in the inferior olivary nuclei (ION), dentate nuclei (DN), midbrain raphe nuclei (MRN), inferior colliculi (IC), mammillary bodies (MB), red nuclei (RN), subthalamic nuclei (STN), lateral geniculate nuclei (LGN), medial geniculate nuclei (MGN), and superior colliculi (SC) was visually classified into the following three categories: good, clearly distinguishable FDG accumulation; fair, obscure contour of FDG accumulation; poor, FDG accumulation indistinguishable from surrounding uptake.ResultsAmong individual18F-FDG PET images with OSEM iterations of 4, 16, 64, and 256 + TOF + PSF, the iteration numbers that showed the best visibility in each structure were as follows: ION, MRN, LGN, MGN, and SC, iteration 64; DN, iteration 16; IC, iterations 16, 64, and 256; MB, iterations 64 and 256; and RN and STN, iterations 16 and 64, respectively. Of the four iterations, the18F-FDG PET image of iteration 64 visualized FDG accumulation in small structures in and around the brainstem most clearly (good, 98 structures; fair, 2 structures).ConclusionsA clinically available WB SiPM-PET scanner is useful for visualizing physiological FDG uptake in small brain nuclei, using a sufficiently high number of iterations for OSEM with TOF and PSF reconstructions.

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Section: Discussionmentioning

confidence: 99%

Visualization of small brain nuclei with a high-spatial resolution, clinically available whole-body PET scanner

Shinohara,

Ibaraki,

Matsubara

et al. 2023

Ann Nucl Med

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“…This can be a proof of better imaging performance of VRAIN than HRRT. For the comparison with BresTome, of which crystal size is 2.1 mm×15 mm long, another clinical image of VRAIN (Iwao et al 2022) can be compared with clinical images in Ishii et al (2022), and the comparison is shown in Supplemental figure 3. The similar slices which can be easily compared with Ishii et al (2022) are shown.…”

Section: Discussionmentioning

confidence: 99%

“…For the comparison with BresTome, of which crystal size is 2.1 mm×15 mm long, another clinical image of VRAIN (Iwao et al 2022) can be compared with clinical images in Ishii et al (2022), and the comparison is shown in Supplemental figure 3. The similar slices which can be easily compared with Ishii et al (2022) are shown. Acquisition time of 30 min and injected activity at the start time of acqusition (123 MBq) are the same, while post-injection time is different (107 min in VRAIN and 71±5 min in BresTome) and the subject in BresTome was a 85 years old male patient with mild cognitive impairment due to AD (22 years old healthy male volunteer in VRAIN).…”

Section: Discussionmentioning

confidence: 99%

Performance evaluation of VRAIN: a brain-dedicated PET with a hemispherical detector arrangement

et al. 2022

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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 mm2 active 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 performed 18F-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 (NECR) was 144 kcps at 9.8 kBq/mL and the sensitivity was 25 kcps/MBq. 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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“…This means that one scanner can be used for both dhPET and dbPET. Recent studies have evaluated the image quality provided by this scanner as a dhPET system [ 9 , 10 , 11 ], but regarding its image quality as a dbPET system, we have found no reports of a comparison between this scanner and its prior model, the PMT-based dbPET scanner. We conducted the present phantom study to qualitatively and quantitatively compare the image quality of organ-specific SiPM-based TOF-PET and PMT-based PET for breast imaging.…”

Section: Introductionmentioning

confidence: 99%

Organ-Specific Positron Emission Tomography Scanners for Breast Imaging: Comparison between the Performances of Prior and Novel Models

et al. 2023

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The performances of photomultiplier tube (PMT)-based dedicated breast positron emission tomography (PET) and silicon photomultiplier tube (SiPM)-based time-of-flight (TOF) PET, which is applicable not only to breast imaging but also to head imaging, were compared using a phantom study. A cylindrical phantom containing four spheres (3–10 mm in diameter) filled with 18F-FDG at two signal-to-background ratios (SBRs), 4:1 and 8:1, was scanned. The phantom images, which were reconstructed using three-dimensional list-mode dynamic row-action maximum likelihood algorithm with various β-values and post-smoothing filters, were visually and quantitatively compared. Visual evaluation showed that the 3 mm sphere was more clearly visualized with higher β and smaller post-filters, while the background was noisier; SiPM-based TOF-PET was superior to PMT-based dbPET in sharpness, smoothness, and detectability, although the background was noisier at the SBR of 8:1. Quantitative evaluation revealed that the detection index (DI) and recovery coefficient (CRC) of SiPM-based TOF-PET images were higher than those of PMT-based PET images, despite a higher background coefficient of variation (CVBG). The two organ-specific PET systems showed that a 3 mm lesion in the breast could be visualized at the center of the detector, and there was less noise in the SiPM-based TOF-PET image.

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High-Resolution Silicon Photomultiplier Time-of-Flight Dedicated Head PET System for Clinical Brain Studies

Cited by 9 publications

References 23 publications

Visualization of small brain nuclei with a high-spatial resolution, clinically available whole-body PET scanner

Visualization of small brain nuclei with a high-spatial resolution, clinically available whole-body PET scanner

Performance evaluation of VRAIN: a brain-dedicated PET with a hemispherical detector arrangement

Organ-Specific Positron Emission Tomography Scanners for Breast Imaging: Comparison between the Performances of Prior and Novel Models

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