Predictors of microscopic portal vein invasion by hepatocellular carcinoma: Measurement of portal perfusion defect area ratio

Objective: Microscopic portal vein invasion (PVI) by cancer cells is a poor prognostic factor after hepatic resection for hepatocellular carcinoma (HCC). The aim of this study is to predict PVI preoperatively in patients with HCC. Methods: We studied 46 hepatectomized patients who had HCC without any portal venous invasion detected during preoperative radiographic evaluation. We defined the portal perfusion defect area ratio (PPDAR) as the following: the quotient of the maximal portal perfusion defect area, on computed tomography during arterio-portography (CTAP) is divided by the maximal tumor area on magnetic resonance imaging (MRI) or CT. Results: The median PPDAR was 1.3 (mean 1.4 +/- 1.1; ranged from 0.7 to 5.8). The incidence of PVI was 4.5% in patients with a PPDAR < 1.3, 35.7% in those with a PPDAR of 1.3-1.6, 70% in those with a PPDAR >= 1.6 (P = 0.0005). When analyzing the preoperative value of different cut-off points for the PPDAR, the lowest P-value by Fisher's exact test was achieved when the PPDAR threshold was 1.6 (P = 0.0012). The sensitivity was 58%, and specificity was 91% with this cut-off value. On univariate analyses, factors that significantly correlated with PVI were PPDAR (P = 0.0012), serum levels of des-gamma-carboxy prothrombin (P = 0.033), and tumor size (P = 0.0126). On multivariate analysis, PPDAR was the only significant independent predictor of PVI. Conclusion: Our study shows that PPDAR is a new concept, which is useful in predicting PVI and that a value >= 1.6 is predictive of PVI.