Value of Liver Parenchymal Phase Contrast-Enhanced Sonography to Diagnose Premalignant and Borderline Lesions and Overt Hepatocellular Carcinoma

OBJECTIVE. The objective of our study was to investigate whether liver parenchymal phase contrast-enhanced sonography can provide additional information for assessing histologic grades of hepatocellular carcinoma (HCC). SUBJECTS AND METHODS. Contrast-enhanced sonography using Levovist of 50 hepatic nodules was performed. The vascular and liver parenchymal perfusion patterns were evaluated. The sensitivity, specificity, and accuracy of the histologic diagnosis of the tumors using vascular phase imaging only and systematically combined vascular phase imaging with liver parenchymal phase imaging were calculated. We also performed histologic examination and immunostaining for the detection of Kupffer cells and calculated the Kupffer cell count in the tumorous tissue relative to that in the nontumorous tissue (Kupffer cell ratio) and quantitatively evaluated the relationship between the Kupffer cell ratio and the perfusion patterns seen on liver parenchymal phase imaging. RESULTS. The specificity and accuracy of contrast-enhanced sonography in the diagnosis of dysplastic nodules and of moderately and poorly differentiated HCCs were improved by adding liver parenchymal phase imaging (dysplastic nodules, 74% and 78% vs 83% and 86%, respectively; moderately and poorly differentiated HCCs, 74% and 86% vs 85% and 92%). The diagnostic accuracy of contrast-enhanced sonography for dysplastic nodules showed a trend of improvement with the addition of liver parenchymal phase imaging (p = 0.07). Kupffer cell ratios for tumors that showed hypoperfusion during the liver parenchymal phase were significantly lower than those for tumors showing isoperfusion (p < 0.05). CONCLUSION. Adding liver parenchymal phase imaging to contrast-enhanced sonography protocols may yield additional information that can be used to assess histologic grades of tumor and that leads to an improvement in the differential diagnosis of nodular lesions associated with the cirrhotic liver. Further case studies are required in larger numbers of patients for a longer follow-up period.