View larger version (327K)

Figure 2a. HCC in a different patient than in (a) Conventional power Doppler US images. The image obtained before injection of the contrast agent shows dotlike power Doppler US signals in the peripheral and central portions of an exophytic tumor (straight arrows). The conventional power Doppler US images obtained at 30 seconds (sec), 60 seconds, 2 minutes (min), 3 minutes, and 5 minutes after injection show a marked increase in the number and intensity of intratumoral power Doppler US signals. The enhanced area is maximal on the 60-second image and decreases subsequently. Severe blooming artifacts (curved arrow) around the inferior vena cava are noted. (b) Harmonic power Doppler US images. The image obtained before contrast agent injection shows no intratumoral power Doppler US signals. The harmonic power Doppler US images obtained at 30 seconds (sec), 60 seconds, 2 minutes (min), 3 minutes, and 5 minutes after injection show dotlike and linear power Doppler US signals within the tumor. The power Doppler US signals in the tumor and adjacent normal liver in b are smaller in extent and lower in signal intensity than those in a. However, blooming artifacts around the inferior vena cava are not seen in b.