Focal Nodular Hyperplasia of the Liver: Contrast-Enhanced Ultrasonographic Features With Sonazoid

OBJECTIVES: To investigate ultrasonographic features of focal nodular hyperplasia of the liver with contrast-enhanced ultrasonography (CEUS) using Sonazoid (perflubutane; GE Healthcare, Oslo, Norway). METHODS: Thirty-one patients with 31 focal nodular hyperplasia nodules who underwent CEUS using Sonazoid between July 2012 and February 2015 were included in this study. After the microbubble contrast agent was injected, intermittent CEUS images were obtained during the following 4 phases: arterial (10-40 seconds), portal venous (60-90 seconds), delayed (3 minutes), and Kupffer (>10 minutes). Three abdominal radiologists retrospectively reviewed the images and achieved consensus for vascular (central artery, stellate vascularity, and centrifugal enhancement) and dynamic enhancement patterns during the late arterial, portal venous, delayed, and Kupffer phases. RESULTS: The patients included 12 men and 19 women (age range, 21-82 years; mean, 47 years). The mean diameter of the lesions ± SD was 2.2 ± 0.9 cm (range, 1.0-4.0 cm). On CEUS, 24 of 31 lesions (77.4%) showed central artery and stellate vascularity in the early arterial phase, and 25 (80.6%) showed centrifugal enhancement. Twenty-six lesions (83.9%) were hyperechoic during the late arterial phase and showed hyperenhancement or isoenhancement during the serial dynamic phases. Kupffer-phase images indicated that only 2 lesions (6.5%) were hypoechoic compared with surrounding liver parenchyma, whereas 29 (93.5%) remained either hyperechoic (2 [6.5%]) or isoechoic (27 [87.1%]). CONCLUSIONS: Contrast-enhanced US using Sonazoid for focal nodular hyperplasia showed typical vascular patterns of central artery vascularity, stellate vascularity, and centrifugal enhancement. Most cases were either hyperenhanced or isoenhanced on serial dynamic- and Kupffer-phase imaging. Based on these results, CEUS can provide useful information for noninvasive focal nodular hyperplasia diagnoses.