Superior Identification of Metastatic Lesions by 68Ga-FAPI-46 to 18F-FDG PET/CT in a Case of SMARCA4-Deficient Undifferentiated Carcinoma of Stomach

Abstract

SMARCA4-deficient undifferentiated carcinoma is a new clinical entity characterized by SMARCA4 inactivation and has a dismal prognosis because of rapid growth. In this case, we reported 18F-FDG and 68Ga-FAPI-46 PET/CT imaging findings in a patient with SMARCA4-deficient undifferentiated carcinoma of stomach. 68Ga-FAPI-46 PET/CT showed much higher tumor-to-background contrast of primary tumor and revealed more metastatic lesions than 18F-FDG PET/CT. This case demonstrated the superiority of 68Ga-FAPI PET/CT over 18F-FDG for identifying both primary and metastatic lesions in SMARCA4-deficient undifferentiated carcinoma. This observation may add the information on the benefit of FAPI PET in oncology imaging.