Predictability of preoperative 18F-FDG PET for histopathological differentiation and early recurrence of primary malignant intrahepatic tumors

Abstract

OBJECTIVE: The limited studies with 18F-fluorodeoxyglucose (18F-FDG)-PET reported results and interpretations that differed between hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (IHCC). We investigated the correlation between preoperative PET results and postoperative prognosis, including early (time-to-recurrence<6 months) tumor recurrence, and histopathological tumor differentiation in patients who had undergone surgery for primary malignant intrahepatic tumors, including HCC and IHCC. MATERIALS AND METHODS: We retrospectively reviewed 357 patients who had undergone curative surgery for malignant hepatic tumors, including primary HCC or IHCC, other than Klatskin tumors at a tertiary academic hospital between January 2005 and June 2012. All patients had undergone an 18F-FDG PET/computed tomography scan preoperatively and the maximum standardized uptake value of the tumor (max SUV tumor) and the tumor-to-nontumor SUV ratio (TNR) were calculated from 18F-FDG uptake. Histopathological differentiation grading was confirmed postoperatively. RESULTS: Among the patients, 115 cases with primary malignant intrahepatic tumors fulfilled the inclusion criteria. On univariate analysis, preoperative max SUV tumor and TNR showed a correlation with the overall and early tumor recurrence of HCC, but only max SUV tumor was associated with overall and early recurrence of IHCC (P<0.05). When considering postoperative histopathological differentiation, a correlation between max SUV tumor and TNR with HCC and between max SUV tumor and IHCC was found (P<0.05). However, on multivariate analysis, only early recurrence was associated with TNR in HCC and with max SUV tumor in IHCC. CONCLUSION: A preoperative 18F-FDG PET scan can be considered a useful reference for postoperative tumor recurrence and histopathological differentiation in cases of primary malignant intrahepatic tumors. 18F-FDG PET scan results should be interpreted separately for malignant liver tumors.