LAUSR

Ga-68 labeled fibroblast-activated protein inhibitor (FAPI) with favorable tumor-to-background contrast is a promising PET tracer, which has been proven significantly more sensitive than [F]-FDG in the detection of various types of cancer [1–3]. Several studies have showed the novel application of [Ga]Ga-FAPI-04 PET/CT in identifying both primary and metastatic lesions of the gastric signet-ring cell carcinoma (SRCC), which is remarkably superior to [F]-FDG [2–5]. The colorectal SRCC is a rare malignant tumor with poor prognosis. Here, we report the first case of [Ga]Ga-FAPI04 PET/CT imaging in SRCC of sigmoid colon. A 23-year-old female was admitted to our hospital with complaint of recurrent lower abdominal colic and diarrhea for 1 month. The pathological finding of colonoscopy biopsy in other hospital was SRCC of sigmoid colon. [F]-FDG PET/ CT was performed for staging and showed wall thickening of the sigmoid colon (Figure a, white arrow), enlarged lymph nodes in the retroperitoneum (Figure a, red arrows), and diffuse