Detection and differential diagnosis of hepatic masses using pulse inversion harmonic imaging during the liver‐specific late phase of contrast enhancement with levovist

Purpose The purpose of this study was to investigate whether late‐phase pulse inversion harmonic imaging (PIHI) increases conspicuity in hepatic masses, helps to differentiate benign from malignant lesions, and demonstrates a greater number of and smaller metastatic lesions than do conventional (fundamental) sonography and helical CT. Methods Thirty patients (17 women and 13 men; age range, 35–77 years; mean age, 54 years) with known or suspected liver masses were evaluated using both fundamental sonography and contrast‐enhanced PIHI during the liver‐specific late phase of Levovist. The patients also underwent contrast‐enhanced triphasic helical CT examinations within 1 week after sonography. In 4 of the patients, gadolinium‐enhanced MRI was also performed as a part of their clinical work‐up. Results The increase in the lesions' conspicuity on PIHI compared with fundamental sonography was significantly greater in malignant lesions than in benign lesions ( p < 0.001). An echogenic rim was observed on PIHI in 8 (53%) of 15 malignant lesions. The mean number of metastatic lesions visualized on PIHI (5.5 ± 5.3) was significantly higher than the mean number visualized on fundamental sonography (2.5 ± 2.1, p < 0.05). Although lesions as small as 3 mm were observed on PIHI, the mean sizes of the smallest lesions demonstrated using fundamental sonography, PIHI, and helical CT were not significantly different. Conclusions Late‐phase PIHI is a useful technique for characterizing hepatic lesions and demonstrating both a greater number of and smaller metastases. It may help to differentiate benign from malignant liver masses and may obviate unnecessary and expensive further imaging. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30:203–212, 2002; Published online in Wiley InterScience (www.interscience. wiley.com). DOI: 10.1002/jcu.10053