CT prediction of histological grade of hypervascular hepatocellular carcinoma: utility of the portal phase

Abstract

To elucidate whether the attenuation of hypervascular hepatocellular carcinoma (HCC) on the portal phase of dynamic CT is correlated with histological grade. This study group consisted of 66 patients with 74 surgically resected, hypervascular HCCs. On a preoperative dynamic study with a 64-multidetector row CT, the portal phase was scanned 60 s after injecting the contrast agent following the pre-contrast image and hepatic arterial phase. The tumor attenuation of each HCC on the portal phase was categorized into high, iso-, or low, and was compared with the predominant histological grade using Mann–Whitney’s U test. Twenty-nine, 29, and 16 HCCs showed high, iso-, and low attenuation on the portal phase, respectively. Tumors were classified into three well- (w-), 58 moderately (m-), or 13 poorly (p-) differentiated HCCs. The tumor attenuation of p-HCC on the portal phase was significantly lower than those of w-HCC and m-HCC (p < 0.05 and p < 0.00001). The tumor attenuation on the portal phase may help when diagnosing the histological grade of hypervascular HCC. p-HCC are considered to show a faster contrast washout than w-HCC and m-HCC.