Tumor-to-muscle ratio of 8F-FDG PET for predicting histologic features and recurrence of HCC.

Abstract

Background/aims: Hepatocellular carcinoma (HCC) recurrence is observed in up to 70-80% of patients despite a curative treatment. Microvascular invasion (MVI) and poor differentiation are strong risk factors for recurrence, but these cannot be known preoperatively. The aim of this study was to investigate the correlation of 18F-FDG PET with MVI and differentiation, and predictive role of tumor-to-background ratio of PET for recurrence in HCC.

Methodology: Fifty-four patients had 18F-FDG PET/CT study before surgical resection as a first treatment of HCC between December 2008 and December 2012. We analyzed the predictive role of metabolic parameters of PET for recurrence of HCC. Maximal standardized uptake value, tumor-to-nontumor ratio, tumor-to-muscle ratio (TMR) and tumor-to-blood ratio were tested as metabolic index of 18F-FDG PET.

Results: Twenty-seven patients had increased uptake in preoperative PET and 14 (51.9%) of them experienced the recurrence. Increased uptake in PET and TMR were associated with MVI (p = 0.04, p = 0.005) and histologic differentiation (p = 0.018, p = 0.002). MVI was the only predictive factor for re- currence in multivariate analysis although TMR ≥ 6.36 showed a favorable result despite no statistical significance (p = 0.061).

Conclusions: Increased 18F-FDG uptake of HCC, especially high TMR might be correlated with MVI and poor differentiation, and tends to have a risk for recurrence in HCC.