在放射性碘不敏感的滤泡细胞源性甲状腺癌（RAI-R-FCTC）的背景下，[18F]F-FDG PET/CT作为广泛应用和有价值的诊断成像方法。然而，越来越多的人对利用针对癌相关成纤维细胞（CAFs）的分子成像探针作为替代方法产生了兴趣。本研究旨在比较[68Ga]Ga-DOTA.SA.FAPi和[18F]F-FDG PET/CT在RAI-R-FCTC患者中的诊断能力。在这项回顾性研究中，共纳入117名RAI-R-FCTC患者。研究人群包括68名女性和49名男性，平均年龄为53.2 ± 11.7岁。本研究的目的是对RAI-R-FCTC患者的[68Ga]Ga-DOTA.SA.FAPi和[18F]F-FDG PET/CT扫描进行全面的定性和定量评估。定性评估包括比较基于患者和基于病变的两种扫描的视觉解释，而定量评估则包括分析校正为瘦体量的标准摄取值（SULpeak和SULavg）。通过将扫描结果与诊断性计算机断层扫描和/或组织病理学检查的形态学结果相关，以验证扫描结果。在117名RAI-R-FCTC患者中，60名患者有单侧局部病变，9名患者有双侧病变，两个PET扫描的检出率完全一致。与[18F]F-FDG相比，[68Ga]Ga-DOTA.SA.FAPi在淋巴结（95.4% vs 86.6%，p<0.0001），肝转移（100% vs. 81.3%，p<0.0001）和脑转移（100% vs. 39%，p<0.0001）的检出率更高。两种示踪剂对胸膜和骨转移的检出率相似。对于肺转移，[68Ga]Ga-DOTA.SA.FAPi的检出率为81.7%，而[18F]F-FDG的检出率为64.6%。值得注意的是，[68Ga]Ga-DOTA.SA.FAPi能够检测到[18F]F-FDG扫描未能发现的肠道转移。两种示踪剂的中位数标准化摄取值（SUL）基本相当，仅在脑转移（SULpeak [68Ga]Ga-DOTA.SA.FAPi vs. [18F]F-FDG: 13.9 vs. 6.7，p-0.0001）和肌肉转移（SULpeak [68Ga]Ga-DOTA.SA.FAPi vs. [18F]F-FDG: 9.56 vs. 5.62，p-0.0085）上，[68Ga]Ga-DOTA.SA.FAPi表现出较高的摄取。研究结果显示，与[18F]F-FDG PET/CT相比，[68Ga]Ga-DOTA.SA.FAPi在RAI-R-FCTC患者中检测淋巴结、肝、肠道和脑转移方面表现出卓越的性能。这些发现突显了[68Ga]Ga-DOTA.SA.FAPi在RAI-R-FCTC成像中作为治疗先测联用工具的潜力。© 2023. 作者，独家许可给Springer-Verlag GmbH Germany 即Springer Nature的一部分。

In the context of radioiodine-resistant follicular-cell derived thyroid cancers (RAI-R-FCTC), [18F]F-FDG PET/CT serves as a widely used and valuable diagnostic imaging method. However, there is growing interest in utilizing molecular imaging probes that target cancer-associated fibroblasts (CAFs) as an alternative approach. This study sought to compare the diagnostic capabilities of [68Ga]Ga-DOTA.SA.FAPi and [18F]F-FDG PET/CT in patients with RAI-R-FCTC.In this retrospective study, a total of 117 patients with RAI-R-FCTC were included. The study population consisted of 68 females and 49 males, with a mean age of 53.2 ± 11.7 years. The aim of the study was to perform a comprehensive qualitative and quantitative assessment of [68Ga]Ga-DOTA.SA.FAPi and [18F]F-FDG PET/CT scans in RAI-R-FCTC patients. The qualitative assessment involved comparing patient-based and lesion-based visual interpretations of both scans, while the quantitative assessment included analyzing standardized uptake values corrected for lean body mass (SULpeak and SULavg). The findings obtained from the scans were validated by correlating them with morphological findings from diagnostic computed tomography and/or histopathological examination.Among the 117 RAI-R-FCTC patients, 60 had unilateral local disease, and 9 had bilateral lesions with complete concordance in the detection rate on both PET scans. [68Ga]Ga-DOTA.SA.FAPi had a higher detection rate for lymph nodes (95.4% vs 86.6%, p<0.0001), liver metastases (100% vs. 81.3%, p<0.0001), and brain metastases (100% vs. 39%, p<0.0001) compared to [18F]F-FDG. The detection rates for pleural and bone metastases were similar between the two radiotracers. For lung metastases, [68Ga]Ga-DOTA.SA.FAPi showed a detection rate of 81.7%, whereas [18F]F-FDG had a detection rate of 64.6%. Remarkably, [68Ga]Ga-DOTA.SA.FAPi was able to detect a bowel metastasis that was missed on [18F]F-FDG scan. The median standardized uptake values (SUL) were generally comparable between the two radiotracers, except for brain metastases (SULpeak [68Ga]Ga-DOTA.SA.FAPi vs. [18F]F-FDG: 13.9 vs. 6.7, p-0.0001) and muscle metastases (SULpeak [68Ga]Ga-DOTA.SA.FAPi vs. [18F]F-FDG: 9.56 vs. 5.62, p-0.0085), where [68Ga]Ga-DOTA.SA.FAPi exhibited higher uptake.The study results demonstrate the superior performance of [68Ga]Ga-DOTA.SA.FAPi compared to [18F]F-FDG PET/CT in detecting lymph nodal, liver, bowel, and brain metastases in patients with RAI-R-FCTC. These findings highlight the potential of [68Ga]Ga-DOTA.SA.FAPi as a theranostic tool that can complement the benefits of [18F]F-FDG PET/CT in the imaging of RAI-R-FCTC.© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.