[The tissue characterization of focal liver lesions by color Doppler echography]

To investigate color-Doppler capabilities in tissue characterization, 47 hepatic lesions were studied. The real-time morphologic appearance of the lesions was studied first and then color flow images were acquired, assessing color areas and the distribution of blood flow for each lesion. For quantitative Doppler study, the color Doppler signal was used as a guide to obtain the Doppler spectrum and to measure flow velocities and pulsatility index (PI) values. Data were plotted and analyzed statistically; criteria for differentiating malignant from benign hepatic tumors and the patterns suggestive of either condition were proposed. Absolutely no Doppler signal was observed in avascular or necrotic lesions and in low-flow tumors, e.g., metastases (10%) and hemangiomas (63%). Many color signals at the periphery and within tumor masses were observed in highly vascular lesions, e.g., hepatocellular carcinomas (60%) and focal nodular hyperplasia (80%). Multiple afferent vessels and a "basket-like" pattern were detected in a high percentage of hepatocellular carcinomas. High-flow velocities (> 0.85 m/s perilesional systolic velocity and > 0.80 m/s intralesional systolic velocity) and high PI values (> 1.5 perilesional PI and > 0.90 intralesional PI) are suggestive of malignancy. Particularly, 0.90 intralesional PI cutoff value exhibits 89% specificity and 82% sensitivity in benign versus malignant differential diagnosis. Our results suggest that color-Doppler US is a useful means of studying the hemodynamics of hepatic tumors which increases US diagnostic accuracy.