68Ga-FAPI-04 Positron Emission Tomography Distinguishes Malignancy From 18F-FDG-Avid Colorectal Lesions
Chengfang Shangguan, Yang Chen, Zhaopeng Shi, Ying Miao, Wangxi Hai, Yan Shen, Qing Qu, Biao Li, Jun Mi
Abstract
PurposeLesions with a high uptake of 18-fluorodeoxyglucose (18F-FDG) on positron emission tomography / computed tomography (PET/CT) can be benign and malignant. New radiotracers, such as the gallium-68 (68Ga) labeled fibroblast activation protein inhibitor-4 (FAPI-04), could be used to diagnose colorectal carcinoma. This study aimed to evaluate the efficacy of 68Ga-FAPI-04 PET in differentiating benign from malignant in 18F-FDG-avid colorectal lesions.Methods and MaterialsAn azoxymethane/dextran sodium sulfate (AOM/DSS) - induced rat colorectal tumor model was developed. Double tracer 68Ga-FAPI-04 and 18F-FDG PET/CT were applied in the rat model and 22 patients. The PET/CT data were analyzed with enteroscopy, histopathological observations, immunohistochemistry (IHC) staining and radioautography results. One hundred seventy-two patients with pathologically confirmed colorectal lesions were enrolled in FAP IHC staining.ResultsWe found that 68Ga-FAPI-04 PET/CT imaging accurately distinguished the malignancy from benign inflammatory lesions in an AOM/DSS-induced rat colorectal tumor model. Eight out of 22 gastric cancer patients without colorectal carcinoma had 18F-FDG uptake in the colorectum, but 68Ga-FAPI-04 PET was negative in these sites. An inflammatory lesion or adenoma did not interfere with 68Ga-FAPI-04 PET imaging. Among the 18F-FDG-avid colorectal lesions, 85.1% (80 out of 94) of pathologically malignant lesions were FAP-positive, and only 20.5% (16 out of 78) of the premalignant or benign lesions had a week 68Ga-FAPI-04 uptake.Conclusion68Ga-FAPI-04 PET/CT could be used to distinguish between benign and malignant in 18F-FDG-avid colorectal lesions.