Department of Diagnostic Radiology, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan.
Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan.
Ann Nucl Med. 2019 Nov;33(11):848-854. doi: 10.1007/s12149-019-01397-y. Epub 2019 Aug 27.
Many studies have demonstrated the superiority of white matter (WM) reference regions (RR) in amyloid PET studies in comparison to cerebellar RR. However, the principle behind its improved measurement stability is yet to be elucidated. Our study aimed to determine the origin of WM stability; stability over cerebral blood flow and input function fluctuation or the greater statistical noise in the cerebellum due to its smaller size and its location in the axial periphery of the PET scanner bore.
We conducted simulations of [[Formula: see text]F] florbetapir using in-house program varying [Formula: see text] and input function, and adding statistical noise.
Our simulations revealed that WM RR were more susceptible to CBF variation and input function fluctuation than cerebellar RR. WM RR did not gave superior measurement stability unless cerebellar statistical noise exceeded 4.55 times that in WM, a figure often surpassed in traditional amyloid PET studies. The greater statistical noise in cerebellum is likely the etiology for improved measurement stability of WM RR.
A longitudinal [[Formula: see text]F] florbetapir PET study should be conducted with a long bore PET. It can also be hypothesized that a second scan with the cerebellum in the axial center of a 3D PET, using a cerebellar RR to calculate changes in tracer concentration may improve the measurement stability of longitudinal [[Formula: see text]F] florbetapir studies.
许多研究表明，与小脑参考区 (RR) 相比，脑白质 (WM)RR 在淀粉样蛋白 PET 研究中具有优越性。然而，其测量稳定性提高的原理仍有待阐明。我们的研究旨在确定 WM 稳定性的起源；是由于其较小的体积及其在 PET 扫描仪轴孔周边的位置，导致统计噪声较大，还是由于其对脑血流和输入函数波动的稳定性更好。
我们使用内部程序模拟了 [[Formula: see text]F]florbetapir，该程序改变了 [Formula: see text] 和输入函数，并添加了统计噪声。
我们的模拟表明，WM RR 比小脑 RR 更容易受到 CBF 变化和输入函数波动的影响。除非小脑的统计噪声超过 WM 统计噪声的 4.55 倍，否则 WM RR 不会提供更好的测量稳定性，而在传统的淀粉样蛋白 PET 研究中，这一数字通常会超过。小脑中较大的统计噪声可能是 WM RR 测量稳定性提高的原因。
应使用长轴孔 PET 进行纵向 [[Formula: see text]F]florbetapir PET 研究。还可以假设，使用小脑 RR 计算示踪剂浓度变化的 3D PET 轴向中心的第二次小脑扫描，可能会提高纵向 [[Formula: see text]F]florbetapir 研究的测量稳定性。
