Comparison of clinical utility of 18F-FAPI-42 and 18F-FDG PET/CT imaging in the diagnosis of newly diagnosed lung cancer / 中华核医学与分子影像杂志

ABSTRACT

Objective:To compare the clinical utility of 18F-fibroblast activating protein inhibitor (FAPI)-42 and 18F-fluorodeoxyglucose (FDG) PET/CT imaging in newly diagnosed lung cancer patients. Methods:From May 2020 to September 2021, the images of 43 lung cancer patients (32 males, 11 females, age 37-80 years) who pathologically confirmed and received 18F-FDG and 18F-FAPI-42 PET/CT within 2 weeks in the First Affiliated Hospital of Guangzhou Medical University were prospectively analyzed. The maximum standardized uptake value (SUV max) of 18F-FDG and 18F-FAPI-42 and the number of lesions detected by 2 imaging methods were compared by using paired t test and Wilcoxon rank sum test. Results:The 43 newly diagnosed lung cancer patients included 35 adenocarcinoma, 2 squamous cell carcinoma, 4 small cell lung cancer, and 2 high-grade neuroendocrine tumors. 18F-FAPI-42 had a very high tumor uptake (SUV max 12.24±3.97) and lesion detection rate (positive rate 100%(37/37)) in primary lung adenocarcinoma and squamous cell carcinoma. The uptake of 18F-FAPI-42 in lymph node (10.13±5.43), pleura (6.75(4.96, 8.58)) and bone lesion (7.18(4.33, 9.66)) were significantly higher than those of 18F-FDG (6.35±3.30, 2.69(1.81, 5.00), 4.38(2.96, 6.36); t=12.19, z values 5.47, 5.79, all P<0.001). In lung adenocarcinoma and squamous cell carcinoma, although the uptake of 18F-FAPI-42 in brain metastases was significantly lower than that of 18F-FDG (0.72(0.15, 1.82) vs 6.53(4.65, 9.34); z=6.42, P<0.001), the tumor/background (T/B) ratio was significantly higher than that of 18F-FDG (3.54(1.15, 14.88) vs 0.96(0.77, 1.04); z=6.05, P<0.001). In lung adenocarcinoma and squamous cell carcinoma, the number of lesions detected by 18F-FAPI-42 PET/CT was significantly more than that of 18F-FDG (lymph node 6.0(2.3, 11.5) vs 4.5(2.0, 10.8); brain 2.0(1.0, 3.0) vs 0.0(0.0, 0.0); pleura 6.0(2.8, 10.0) vs 4.0(0.8, 5.5); z values 2.16, 3.10, 2.04, all P<0.05). However, in high-grade neuroendocrine tumors and small cell lung cancer, the SUV max of 18F-FAPI-42 in primary lesions (8.05±2.60), lymph node lesions (5.98±2.21) and brain lesions (0.44(0.13, 0.82)) were lower than those of 18F-FDG (16.28±5.17, 12.30±5.47, 4.94(4.84, 6.25); t values 3.58, 7.52, z=3.06, all P<0.05). Conclusions:In lung adenocarcinoma and squamous cell carcinoma, 18F-FAPI-42 has a very high tumor uptake and lesion detection rate in primary tumor. In addition, compared with 18F-FDG PET/CT, 18F-FAPI-42 PET/CT shows clearer tumor contours and more lesions. Therefore, 18F-FAPI-42 is more suitable for preliminary staging of lung adenocarcinoma and squamous cell carcinoma than 18F-FDG, while the opposite is true in small cell lung cancer and high-grade neuroendocrine tumors.