Triple-phase MDCT of hepatocellular carcinoma.

Abstract

The purpose of this study was to describe the appearances of hepatocellular carcinoma including intralesional contrast washout using a triple-phase liver protocol on an MDCT scanner. Fifty-one patients with newly diagnosed hepatocellular carcinoma underwent standardized triple-phase CT using a multidetector scanner. Pathologic proof was obtained in 35 patients (69%); in 16 patients (31%), hepatocellular carcinoma was diagnosed on clinical and laboratory findings. Two radiologists independently reviewed the CT studies for the appearance and attenuation of the lesions. Intralesional washout of contrast material was evaluated subjectively and objectively. Statistical analysis was performed using Fisher's exact test to analyze the relationships between tumor appearance and alpha-fetoprotein level, tumor grade, and risk factor. Correlation between tumor size and appearance was analyzed using the Student's t test and Wilcoxon's rank sum test. The most common enhancement pattern for hepatocellular carcinoma was hypervascularity on hepatic arterial phase images with a mosaic pattern on both arterial and portal venous images; this finding was seen in 86% and 78% of lesions by the two observers, respectively. A hypervascular component was seen in 96% of lesions by both observers, and the observers recorded 86% and 63% of lesions as showing washout, respectively. Objective washout was present in 76% of lesions. Both subjective and objective washout correlated with an elevated alpha-fetoprotein level (p = 0.01). The appearances of hepatocellular carcinoma on images obtained using MDCT scanners are similar to those described for images obtained using single-detector helical scanners. However, the prevalence of hypervascular hepatocellular carcinoma on MDCT images is higher than previously described on single-detector helical images and most lesions showed washout on portal venous MDCT images.