18F FDG PET/CT in the detection of extrahepatic metastases from hepatocellular carcinoma

The aim of this study was to evaluate the potential role of PET/CT using 18F-fluorodeoxyglucose (FDG) in patients with hepatocellular carcinoma (HCC) in the detection of extrahepatic metastases. A retrospective review was performed of the medical records of patients who underwent FDG PET/CT for staging after being diagnosed with HCC. Images of FDG PET/CT were qualitatively analyzed and the degree of FDG uptake in the primary tumors was visually classified as group I (FDG uptake less than or similar to that of the liver), and group II (FDG uptake higher than that of the liver). The presence of extrahepatic metastases was also evaluated according to the degree of FDG uptake in the primary tumors. Confirmation of the findings on PET/CT was based on histopathology or radiologic follow-up. In a total of 53 patients, 14 patients were classified as group I, and 39 patients as group II. In group I, 2 patients were diagnosed as having extrahepatic metastases and showed mild FDG uptake in those lesions. In group II, 17 patients were diagnosed as having extrahepatic metastases. 14 of 17 patients showed increased FDG uptake in extrahepatic metastases sites and 3 patients showed no definite increased uptake. These 3 patients had lung metastases. There were no false positive lesions. The usefulness of 18F FDG PET/CT in detecting extrahepatic metastases seems to be dependent on the degree of FDG uptake in the primary tumors. Higher FDG uptake in the primary tumor tends to show a higher sensitivity for the detection of extrahepatic distant metastases sites. Based on our results, the degree of FDG uptake in the primary tumors may be an important prognostic factor predictive of aggressive tumor biology in HCCs