Hepatic tumors: contrast agent-enhancement patterns with pulse-inversion harmonic US.
To evaluate contrast agent-enhancement patterns in hepatic hemangiomas, hepatic metastases, and hepatocellular carcinomas (HCCs) at pulse-inversion harmonic ultrasonography (US) with a microbubble contrast agent. Twenty hepatic hemangiomas in 20 patients and 41 malignant hepatic tumors in 23 patients (33 metastases and eight HCCs) were evaluated with pulse-inversion harmonic US. US images were obtained before injection and every 10-15 seconds after injection of a 4-g bolus (300 mg/mL) of SH U 508A (a microbubble contrast agent) for 5 minutes. The contrast-enhancement patterns of 61 hepatic lesions were assessed. Of 20 hemangiomas, 19 revealed peripheral enhancement, which was globular in 14 (70%) and rimlike in five (25%), with centripetal fill-in; the remaining one (5%) showed homogeneous enhancement. In 33 metastases, the enhancement was rimlike in 16 (48%), homogeneous in seven (21%), and stippled in two (6%); in the remaining eight metastases (24%), no enhancement was seen. Of eight HCCs, four (50%) showed homogeneous enhancement and the remaining four (50%) showed heterogeneous enhancement. Centripetal fill-in of lesions with intratumoral enhancement was not seen in any malignancy. Pulse-inversion harmonic US with a microbubble contrast agent is potentially useful for the specific diagnosis of hemangiomas that demonstrate characteristic enhancement features.