Contrast-enhanced power Doppler sonography: improved detection of characteristic flow patterns in focal liver lesions.

Purpose: The aim of this study was to evaluate whether intravenous injection of an ultrasound contrast agent aids in the visualization of focal liver lesions on power Doppler images.

Methods: Fifty patients with focal liver lesions were studied by B-mode and power Doppler sonography before and after intravenous injection of the contrast agent Levovist (galactose-based microbubbles; 10 ml of a concentration of 300 mg/ml). Thirty-two patients had malignant liver lesions (19 metastases, 12 hepatocellular carcinomas, 1 cholangiocellular carcinoma), while 18 had benign lesions (12 hemangiomas, 2 focal nodular hyperplasias, 4 others).

Results: After contrast medium injection, the number of lesions with no intralesional flow dropped from 18 to 9. Flow signal intensity was rated subjectively as marked on contrast-enhanced images in 17 patients; only 4 patients had marked flow on precontrast images. On precontrast studies, central flow in 10 lesions and peripheral flow in 29 lesions could be observed. After enhancement, the numbers increased to 18 and 34 lesions, respectively.

Conclusions: On power Doppler images, a greater number of intratumoral vessels are seen in focal liver lesions after contrast medium administration.