To assess if contrast-enhanced US (US) with sulphur hexafluoride-filled microbubble may improve diagnostic accuracy in benign focal liver lesions characterization.

203 benign focal liver lesions (99 hemangiomas, 50 focal nodular hyperplasias, 11 hepatocellular adenomas, 29 macroregenerative nodules, 12 focal fatty sparing/change areas, 1 solitary necrotic nodule and 1 intrahepatic extramedullary hematopoiesis) in 176 consecutive patients (age 54 ± 13 years) and considered indeterminate at baseline US were scanned by low transmit power after SonoVue (Bracco, Italy) injection at arterial (10-35 secs), portal (50-90 secs) and late (90-300 secs from injection) phase. Two off-site readers reviewed retrospectively baseline and contrast-enhanced scans to assess enhancement pattern, lesions appearance at late phase compared to adjacent liver and to express a diagnostic conclusion on lesions histotype. Histology (n=86) or contrast material-enhanced CT or MR (n=117) were considered as reference standards.

Hemangiomas revealed nodular peripheral enhancement with centripetal fill-in (n=85), dotted (n=3), diffuse (n=7) or absent (n=4) enhancement. Focal nodular hyperplasias revealed central spoke-wheel shaped (n=21) or diffuse (n=29) enhancement with evidence of central hypoechoic scar at late phase in 18 cases. Hepatocellular adenomas revealed diffuse homogeneous (n=7) or heterogeneous (n=4) enhancement with iso (n=7) or hypoechoic (n=4)late appearance. Macroregenerative nodules revealed dotted (n=24) or diffuse (n=5) enhancement with iso (n=22) or hypoechoic (n=7) appearance at late phase. Focal fatty sparing/changes revealed homogeneous enhancement with isoechoic appearance. Necrotic nodule and extramedullary hematopoiesis revealed respectively absent and diffuse enhancement. Additional review of contrast-enhanced US scan improved (P<.05; McNemar test) diagnostic accuracy vs baseline scan in hemangiomas (86% vs 37%), focal nodular hyperplasia (91% vs 79%), hepatocellular adenomas (45% vs 15%), macroregenarative nodules (90% vs 10%) and focal fatty sparing/changes (100% vs 77%).

Contrast-enhanced US improved diagnostic accuracy in benign focal liver lesions characterization.