POSITRON EMISSION TOMOGRAPHY TO STAGE SUSPECTED METASTATIC COLORECTAL-CARCINOMA TO THE LIVER

BACKGROUND: Accurate detection of recurrent colorectal carcinoma remai ns a clinical challenge. Positron emission tomography (PET) using F-18 -fluorodeoxyglucose ((18)FDG) is an imaging technique that allows dire ct evaluation of cellular metabolism, F-18-fluorodeoxyglucose PET was compared to computed tomography (CT) and CT portography for staging me tastatic colorectal carcinoma. PATIENTS AND METHODS: Twenty-four patie nts previously treated for colorectal carcinoma who had suspected recu rrence to the liver underwent an (18)FDG PET scan of the entire body, All patients had either a CT scan of the abdomen (n = 17), a CT portog ram (n = 18), or both (n = 11). The final diagnosis was obtained by ti ssue pathology in 19 patients and clinical follow-up in 5 patients. RE SULTS: A total of 60 suspicious lesions were identified. Of the 55 int rahepatic lesions, 39 were malignant and 16 were benign, Of the 5 extr ahepatic lesions, 4 were mallgnant. The (18)FDG PET imaging had a high er accuracy (93%) than CT and CT portography (both 76%) in detecting m etastatic disease to the liver, and detected unsuspected extrahepatic recurrence in 4 patients. Although the sensitivity of (18)FDG PET (90% ) was slightly lower than that of CT portography (97%), the specificit y was much higher (100% versus 9%), including postsurgical sites. (18) FDG PET altered surgical plans in 6 (25%) of 24 patients. CONCLUSIONS: (18)FDG PET is extremely useful in staging patients with suspected me tastatic colorectal carcinoma to the liver.