Tsuzura Kaede, Wagatsuma Kei, Kamitaka Yuto, Miwa Kenta, Miyaji Noriaki, Kamiya Takashi, Yokotsuka Noriyo, Ishii Kenji
Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan.
School of Allied Health Sciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
Ann Nucl Med. 2025 Jan;39(1):21-30. doi: 10.1007/s12149-024-01973-x. Epub 2024 Aug 29.
Amino acid positron emission tomography (PET) examinations using anti-1-amino-3-[F]-fluorocyclobutane-1-carboxylic acid ([F]FACBC) were allowed for routine clinical use in July 2024. However, phantom test procedures for [F]FACBC reconstruction parameters have not yet been established. The present study aimed to establish new phantom test procedures for [F]FACBC brain PET imaging to determine optimal reconstruction parameters.
Background (BG) activity as well as hot sphere and target-to-background ratios (TBRs) of [F]FACBC were estimated based on brain activity and tumor-to-normal tissue ratios (TNR) in a Japanese clinical trial of [F]FACBC. Phantom experiments proceeded under [F]FACBC or L-[methyl-C]-methionine ([C]MET) conditions. The number of iterations and the Gaussian filter parameters were determined from the reconstruction parameters %contrast and coefficients of variation (CVs) in ordered subset expectation maximization (OSEM) and time-of-flight (TOF) with or without point-spread-function (PSF) correction.
The amounts of activity in the hot spheres and BG were 1.1 and 5.5 kBq/mL, respectively, and the TBR was 5.0 at the start of acquisition. The %contrast of all hot spheres was higher with [F]FACBC than [C]MET, and %contrast converged between 4 and 6 iterations in hot spheres with diameters < 10 mm. We used four iterations for OSEM + TOF and five for OSEM + TOF + PSF correction for [F]FACBC and [C]MET images. The CV was higher for [F]FACBC than [C]MET. The optimal sizes of Gaussian filters for OSEM + TOF and OSEM + TOF + PSF correction of image reconstruction were 5 mm for [F]FACBC, and 4 and 3 mm, respectively, for [C]MET images.
We estimated phantom activity and TBR based on brain activity in a Japanese clinical trial and established new phantom test procedures for [F]FACBC. We recommend that the optimal reconstruction parameters for [F]FACBC should be set to the same number of iterations as [C]MET and that the FWHM of Gaussian filter should have a few mm higher than [C]MET to reduce image noise from brain normal tissue.
使用抗1-氨基-3-[F]-氟环丁烷-1-羧酸（[F]FACBC）的氨基酸正电子发射断层扫描（PET）检查于2024年7月获准用于常规临床。然而，[F]FACBC重建参数的体模测试程序尚未建立。本研究旨在建立用于[F]FACBC脑PET成像的新体模测试程序，以确定最佳重建参数。
基于[F]FACBC在日本一项临床试验中的脑活性和肿瘤与正常组织比值（TNR），估计[F]FACBC的本底（BG）活性以及热球和靶本底比（TBR）。在[F]FACBC或L-[甲基-C]-蛋氨酸（[C]MET）条件下进行体模实验。从有序子集期望最大化（OSEM）和飞行时间（TOF）中，在有或无点扩散函数（PSF）校正的情况下，根据重建参数对比度百分比（%contrast）和变异系数（CV）确定迭代次数和高斯滤波器参数。
采集开始时，热球中的活性量和BG分别为1.1和5.5 kBq/mL，TBR为5.0。所有热球的%contrast在[F]FACBC时高于[C]MET，并且在直径<10 mm的热球中，%contrast在4至6次迭代之间收敛。对于[F]FACBC和[C]MET图像，我们对OSEM + TOF使用4次迭代，对OSEM + TOF + PSF校正使用5次迭代。[F]FACBC的CV高于[C]MET。用于图像重建的OSEM + TOF和OSEM + TOF + PSF校正的高斯滤波器的最佳尺寸，对于[F]FACBC为5 mm，对于[C]MET图像分别为4和3 mm。
我们基于日本一项临床试验中的脑活性估计了体模活性和TBR，并建立了用于[F]FACBC的新体模测试程序。我们建议，[F]FACBC的最佳重建参数应设置为与[C]MET相同的迭代次数，并且高斯滤波器的半高宽（FWHM）应比[C]MET高几毫米，以减少来自脑正常组织的图像噪声。
