Enhancement patterns of small hepatocellular carcinoma (≤ 30 mm) on contrast-enhanced ultrasound: Correlation with clinicopathologic characteristics

Purpose: To analyze the correlation between enhancement patterns of small hepatic carcinomas (HCCs; <= 30 mm) on contrast-enhanced ultrasound (CEUS) and the clinicopathologic characteristics. Methods: The retrospective study included 346 inpatients (288 males and 58 females) with 372 pathologically confirmed small HCCs between January 2017 and December 2018. All patients underwent CEUS examination before pathological examination. Statistical analysis was used to determine the correlation between enhancement patterns of small HCCs on CEUS and clinicopathologic characteristics including serum alpha-feto-protein level, protein induced by vitamin K absence or antagonist-II (PIVKA-II) level, primary or recurrent HCC condition, tumor number, tumor differentiation, tumor size, liver background and microvascular invasion (MVI). Results: Three hundred forty-seven out of 372 (93.3 %) HCCs manifested arterial phase hyper-enhancement (APHE). The arterial enhancement patterns were correlated with the tumor differentiation (odds ratio = 10.336, P = 0.000). Moderately- or poorly-differentiated HCCs were more likely to display APHE than well-differentiated HCCs (96.2 % vs 58.6 %, P < 0.001). Two hundred ninety-five of 372 (79.3 %) HCCs showed washout in the portal venous/late phase. Washout was correlated with serum PIVKA-II level, tumor size, tumor differentiation, and MVI on univariate analysis ( P < 0.05). Logistic regression analysis revealed that only tumor size was significantly associated with washout of small HCCs (odds ratio = 2.335, P = 0.006). Large HCCs (20-30 mm) displayed a higher proportion of washout compared with that of HCCs <= 20 mm. Conclusions: Enhancement patterns of small HCCs on CEUS were significantly correlated with tumor size and tumor differentiation among all clinicopathologic characteristics.