背景：放射性示踪剂氟-18（18F）标记的成纤维细胞活化蛋白抑制剂（FAPI）显示出在可视化多种类型的癌症方面的潜力，但与18F-氟代脱氧葡萄糖（FDG）相比，18F-FAPI对于肺癌的检测准确性尚不确定。目的：评估18F-FAPI基于PET/CT成像对原发性和转移性肺癌病灶的诊断效果，与18F-FDG PET/CT相比。材料和方法：在此前瞻性试验的二次分析中，从2020年12月至2022年4月在单个中心确定诊断为肺癌的连续招募患者，按照相隔超过20小时且在彼此之间七天以内配对进行18F-FAPI和18F-FDG PET/CT检查。组织病理学和临床随访结果用作最终诊断的参考标准。使用麦克马尔检验或配对学生t检验比较18F-FAPI和18F-FDG的摄取。使用麦克马尔χ2检验比较两种技术的诊断准确性。结果：共评估了68名参与者（年龄中位数63岁，IQR 58-68岁，范围42-79岁；男性46人[68%]）。与FDG摄取的平均肿瘤-背景比（TBR）相比，FAPI摄取的TBR在原发性肺肿瘤中较低（25.3 ± 14.0 [标准差] vs 32.1 ± 21.1；P < 0.001），但在淋巴结转移（7.5 ± 6.6 vs 5.9 ± 8.6；P < 0.001）和骨转移（8.6 ± 5.4 vs 4.3 ± 2.3；P < 0.001）中较高。对于评估68名参与者中总共548个病变的诊断准确性，与18F-FDG PET/CT相比，18F-FAPI PET/CT显示出更高的敏感性（99% [392个病变中的397个] vs 87% [397个病变中的346个]；P < 0.001），特异性（93% [151个病变中的141个] vs 79% [151个病变中的120个]；P = 0.004），准确度（97% [548个病变中的533个] vs 85% [548个病变中的466个]；P < 0.001）和阴性预测值（97% [146个病变中的141个] vs 70% [171个病变中的120个]；P < 0.001），但对于阳性预测值没有差异的证据（98% [402个病变中的392个] vs 92% [377个病变中的346个]；P = 0.57）。结论：18F-FAPI PET/CT可能优于18F-FDG PET/CT用于肺癌的检测。© RSNA，2023本文有附加材料可供参考。另见本期编辑人员Zukotynski和Gerbaudo的社论。

Background The radiotracer fluorine 18 (18F)-labeled fibroblast activation protein inhibitor (FAPI) has shown promise for visualizing several types of cancer, but the accuracy of 18F-FAPI compared with 18F-fluorodeoxyglucose (FDG) for the detection of lung cancer remains uncertain. Purpose To evaluate the effectiveness of 18F-FAPI-based PET/CT imaging for the diagnosis of primary and metastatic lung cancer lesions as compared with 18F-FDG PET/CT. Materials and Methods In this secondary analysis of a prospective trial, consecutively recruited patients from a single center with pathologically confirmed lung cancer were prospectively enrolled from December 2020 to April 2022 and underwent paired 18F-FAPI and 18F-FDG PET/CT examinations at intervals of more than 20 hours and within 7 days of each other. Histopathologic and clinical follow-up results were used as reference standards for final diagnoses. 18F-FAPI and 18F-FDG uptake were compared using the McNemar test or paired Student t test. Diagnostic accuracy was compared between the two techniques by using the McNemar χ2 test. Results Sixty-eight participants (median age, 63 years [IQR, 58-68 years; range, 42-79 years]; 46 male [68%]) were evaluated. Compared with the mean tumor-to-background ratio (TBR) for FDG uptake, TBR for FAPI uptake was lower in primary lung tumors (25.3 ± 14.0 [SD] vs 32.1 ± 21.1; P < .001) but higher in metastatic lymph nodes (7.5 ± 6.6 vs 5.9 ± 8.6; P < .001) and bone metastases (8.6 ± 5.4 vs 4.3 ± 2.3; P < .001). For diagnostic accuracy in a total of 548 lesions in 68 participants, compared with 18F-FDG PET/CT, 18F-FAPI PET/CT demonstrated a higher sensitivity (99% [392 of 397 lesions] vs 87% [346 of 397]; P < .001), specificity (93% [141 of 151 lesions] vs 79% [120 of 151]; P = .004), accuracy (97% [533 of 548 lesions] vs 85% [466 of 548]; P < .001), and negative predictive value (97% [141 of 146 lesions] vs 70% [120 of 171 lesions]; P < .001), but there was no evidence of a difference for positive predictive value (98% [392 of 402 lesions] vs 92% [346 of 377 lesions]; P = .57). Conclusion 18F-FAPI PET/CT may be superior to 18F-FDG PET/CT for detecting lung cancer. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Zukotynski and Gerbaudo in this issue.