Department of Nuclear Medicine, University Hospital Duesseldorf, Duesseldorf, Germany.
Department of Nuclear Medicine, University Hospital Heidelberg, INF 400, 69120, Heidelberg, Germany.
Eur J Nucl Med Mol Imaging. 2021 Dec;48(13):4377-4385. doi: 10.1007/s00259-021-05307-1. Epub 2021 Jun 17.
FAPI ligands (fibroblast activation protein inhibitor), a novel class of radiotracers for PET/CT imaging, demonstrated in previous studies rapid and high tumor uptake. The purpose of this study is the head-to-head intra-individual comparison of Ga-FAPI versus standard-of-care F-FDG in PET/CT in organ biodistribution and tumor uptake in patients with various cancers.
This international retrospective multicenter analysis included PET/CT data from 71 patients from 6 centers who underwent both Ga-FAPI and F-FDG PET/CT within a median time interval of 10 days (range 1-89 days). Volumes of interest (VOIs) were manually drawn in normal organs and tumor lesions to quantify tracer uptake by SUVmax and SUVmean. Furthermore, tumor-to-background ratios (TBR) were generated (SUVmax tumor/ SUVmax organ).
A total of 71 patients were studied of, which 28 were female and 43 male (median age 60). In 41 of 71 patients, the primary tumor was present. Forty-three of 71 patients exhibited 162 metastatic lesions. Ga-FAPI uptake in primary tumors and metastases was comparable to F-FDG in most cases. The SUVmax was significantly lower for Ga-FAPI than F-FDG in background tissues such as the brain, oral mucosa, myocardium, blood pool, liver, pancreas, and colon. Thus, Ga-FAPI TBRs were significantly higher than F-FDG TBRs in some sites, including liver and bone metastases.
Quantitative tumor uptake is comparable between Ga-FAPI and F-FDG, but lower background uptake in most normal organs results in equal or higher TBRs for Ga-FAPI. Thus, Ga-FAPI PET/CT may yield improved diagnostic information in various cancers and especially in tumor locations with high physiological F-FDG uptake.
成纤维细胞激活蛋白抑制剂（fibroblast activation protein inhibitor，FAPI）配体是一类新型的正电子发射断层扫描（PET）/计算机断层扫描（CT）放射性示踪剂，在之前的研究中显示出快速和高肿瘤摄取。本研究旨在对头对头个体内比较 Ga-FAPI 与标准 care F-FDG 在不同癌症患者的器官生物分布和肿瘤摄取中的 PET/CT。
这项国际回顾性多中心分析纳入了来自 6 个中心的 71 名患者的 PET/CT 数据，这些患者在中位时间间隔 10 天（范围 1-89 天）内同时进行了 Ga-FAPI 和 F-FDG PET/CT。通过最大标准化摄取值（SUVmax）和平均标准化摄取值（SUVmean）手动勾画感兴趣区（VOI）来量化示踪剂摄取。此外，还生成了肿瘤与背景的比值（TBR）（SUVmax 肿瘤/SUVmax 器官）。
共研究了 71 名患者，其中 28 名女性，43 名男性（中位年龄 60 岁）。在 71 名患者中，41 名有原发性肿瘤。71 名患者中有 43 名存在 162 个转移病灶。在大多数情况下，Ga-FAPI 在原发性肿瘤和转移灶中的摄取与 F-FDG 相当。与 F-FDG 相比，Ga-FAPI 在脑、口腔黏膜、心肌、血池、肝脏、胰腺和结肠等背景组织中的 SUVmax 明显较低。因此，Ga-FAPI 的 TBR 在某些部位，包括肝和骨转移，明显高于 F-FDG 的 TBR。
Ga-FAPI 和 F-FDG 之间的肿瘤摄取定量是可比的，但大多数正常器官的背景摄取较低，导致 Ga-FAPI 的 TBR 相等或更高。因此，Ga-FAPI PET/CT 可能在各种癌症中提供更好的诊断信息，特别是在生理 F-FDG 摄取较高的肿瘤部位。
