Diagnostic value of hepatocellular nodule vascularity after microbubble injection for characterizing malignancy in patients with cirrhosis

OBJECTIVE. The purpose of this study was to assess the diagnostic value of hepatocellular nodule vascularity after microbubble injection for characterization of malignancy in patients with cirrhosis of the liver. MATERIALS AND METHODS. After sulfur hexafluoride -filled microbubble injection, the vascularity of 236 hepatocellular nodules (1 -5 cm in diameter) in 215 patients with cirrhosis (151 men, 64 women; mean age, 62 +/- 11 [SD] years) was evaluated by consensus of three reference radiologists. The relation between nodule vascularity in the arterial (10 -40 seconds from injection) and portal venous (45 seconds to microbubble disappearance) phases and dimension of malignancy was evaluated by multivariate U statistical analysis. Two blinded independent reviewers using reference criteria classified nodules as benign or malignant after review of unenhanced and contrast-enhanced sonograms. RESULTS. The final diagnoses were 96 malignant (84 hepatocellular carcinoma, 12 tumors not hepatocellular carcinoma) and 140 benign nodules (57 regenerative and 13 dysplastic nodules, 70 other benign lesions). Nodule hypervascularity during the arterial phase and hypovascularity during the portal venous phase (odds ratio, 27.78) and nodule diameter greater than 2 cm combined with hypervascularity during the arterial phase and isovascularity or hypervascularity during the portal venous phase (odds ratio, 3.3) were related to the presence of malignancy. Contrast-enhanced sonography improved diagnostic accuracy (unenhanced sonography vs contrast-enhanced sonography, 32% vs 71% for reviewer 1 and 22% vs 66% for reviewer 2; p < 0.05, McNemar test) even though hypervascular nodules 2 cm or smaller (malignant, n = 2; benign, n = 40) that appeared isovascular or hypervascular during the portal venous phase were misclassified. CONCLUSION. Assessment of hepatocellular nodule vascularity after microbubble injection allowed characterization of malignancy, but characterization was limited for hypervascular nodules 2 cm or less in diameter.