Department of Radiology and Nuclear Medicine, Research Institute for Brain and Blood Vessels-Akita, 6-10 Senshu-kubota-machi, Akita, 010-0874, Japan.
Department of Management Science and Engineering, Faculty of System Science and Technology, Akita Prefectural University, Yurihonjo, Japan.
Ann Nucl Med. 2024 Feb;38(2):154-161. doi: 10.1007/s12149-023-01886-1. Epub 2023 Nov 21.
To verify the visibility of physiological F-fluorodeoxyglucose (F-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.
Ten healthy subjects (5 men, 5 women; mean age, 56.0 ± 5.0 years) who underwent F-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.
Among individual F-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, the F-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).
A 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.
使用具有点扩散函数（PSF）重建的全身（WB）硅光电倍增管正电子发射断层扫描（SiPM-PET）扫描仪，通过使用各种迭代次数来验证脑内和脑周围核中生理 F-氟脱氧葡萄糖（F-FDG）摄取的可见性。
10 名健康受试者（5 名男性，5 名女性；平均年龄，56.0±5.0 岁）接受了全身 SiPM-PET 扫描仪的 F-FDG PET/CT 检查以及脑部磁共振成像（MRI）检查，包括自旋回波三维采样完美应用优化对比度使用不同翻转角演化的液体衰减反转恢复（3D-FLAIR）和三维 T1 磁化准备快速梯度回波（T1-MPRAGE）图像。每个采集的 PET 图像均使用有序子集期望最大化（OSEM）进行重建，迭代次数为 4、16、64 和 256（固定 5 个子集）+时间-of-flight（TOF）+PSF。使用归一化互信息标准将每个受试者的重建 PET 图像和 3D-FLAIR 图像与个体 T1-MPRAGE 体积进行配准。对于每个 MR 配准的个体 PET 图像，FDG 摄取的模式在橄榄下核（ION）、齿状核（DN）、中脑蓝斑核（MRN）、下丘（IC）、乳头体（MB）、红核（RN）、丘脑底核（STN）、外侧膝状体核（LGN）、内侧膝状体核（MGN）和上丘（SC）被视觉分类为以下三个类别：良好，可清楚区分 FDG 积聚；公平，FDG 积聚的轮廓模糊；差，FDG 积聚与周围摄取无法区分。
在具有 OSEM 迭代的 4、16、64 和 256+TOF+PSF 的个体 F-FDG PET 图像中，在每个结构中显示最佳可见度的迭代次数如下：ION、MRN、LGN、MGN 和 SC，迭代 64；DN，迭代 16；IC，迭代 16、64 和 256；MB，迭代 64 和 256；RN 和 STN，迭代 16 和 64。在这四个迭代中，迭代 64 的 F-FDG PET 图像最清楚地显示了脑内和脑周围小结构中的 FDG 积聚（良好，98 个结构；公平，2 个结构）。
具有临床可用性的全身 SiPM-PET 扫描仪对于使用足够高的 OSEM 迭代次数（带有 TOF 和 PSF 重建）可视化脑内小核中的生理 FDG 摄取非常有用。
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