Real-time contrast-enhanced ultrasonography of resected and immunohistochemically proven hepatic angiomyolipomas

Abstract

The purpose of this study was to assess real-time contrast-enhanced ultrasound in patients with hepatic angiomyolipomas with respect to contrast-enhancing kinetics and enhancement patterns. Nonlinear, low mechanical index (mechanical index less than 0.2), real-time contrast-enhanced ultrasonography was performed in 18 patients with 19 tumors after 2.4 mL bolus injection of contrast agent SonoVue. All the 19 tumors were surgically resected and immunohistochemically proven sporadic hepatic angiomyolipomas. Inhomogeneous hyperenhancing pattern was detected 16 tumors (84.2%) and homogeneous hyperenhancing pattern in 1 tumor (0.5%) in arterial phase and portal phase, 16 lesions remained hyperenhancement but one lesion became isoenhancement in late phase. Two lesions (10.5%) were detected inhomogeneously hypoenhancement compared to liver parenchyma during arterial, portal, and late phases, with only punctiform internal enhancement. The margin of all the lesions were smooth and well defined on contrast-enhanced ultrasonography, whereas no peripheral nodular arterial enhancement, centripetal filling, or spoke-wheel like enhancement pattern were depicted. Early strong enhancement in arterial phase, rapid washout of contrast agent, and appear hypoechoic to surrounding liver tissue during portal or late phase was not at all observed. Real-time contrast-enhanced ultrasonography can demonstrate typical imaging characteristics of hepatic angiomyolipomas in most cases, that is, inhomogeneous hyperenhancing pattern in arterial phase, prolonged hyperenhancement during portal and late phase with smooth and well-defined margin. This real-time dynamic imaging technique may therefore improve noninvasive characterization and differentiation of this rare, benign, hepatic mesenchymal neoplasm.