Vascularity of hepatocellular carcinoma: Assessment with contrast-enhancedsecond-harmonic versus conventional power Doppler US

PURPOSE: To compare contrast material-enhanced harmonic power Doppler ultra sonography (US) with conventional power Doppler US in depicting the vascula rity of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty patients with nodular HCCs (2.6-13.2 cm in di ameter; mean diameter, 4.8 cm) were prospectively examined with both conven tional and harmonic power Doppler US. US was performed with a 2-4-MHz curve d linear-array transducer according to a standard examination protocol (1,0 00-Hz pulse repetition frequency, medium wall filter, and power gain of 55% -84% for conventional power Doppler US; 700-Hz pulse repetition frequency, low wall filter, and power gain of 95%-98% for harmonic power Doppler US). Serial, dynamic scans were obtained before intravenous injection of the con trast agent (SH U 508A) and at 30, 60, 90, 120, 180, 240, and 300 seconds a fter injection with both techniques. RESULTS: The number of intratumoral power Doppler US signals was similar wi th both techniques at 30-90 seconds after contrast agent injection; however , after 90 seconds, conventional power Doppler US depicted significantly mo re signals than did harmonic power Doppler US. Harmonic power Doppler US wa s superior to conventional power Doppler US in terms of power Doppler artif acts such as "blooming" or motion-related artifacts. CONCLUSION: Although the effective enhancement duration is relatively short compared with that for conventional power Doppler US, contrast-enhanced ha rmonic power Doppler US can be effective in evaluating the vascularity of H CCs because of the advantage of fewer power Doppler artifacts.