Characterization of focal liver lesions with conventional color Doppler and power Doppler sonography

Purpose: To compare conventional color Doppler and power Doppler sonography for characterization of liver lesions on the basis of the flow pattern. Materials and methods: 62 patients with 68 liver lesions (20 hepatocellular carcinomas (HCCs). 18 metastases, 1 cholangiocarcinoma, 18 hemangiomas, 4 focal nodular hyperplasias (FNH). 4 focal fatty infiltration, 3 inflammatory lesions) were evaluated prospectively. Color and Power Doppler images were analyzed by two radiologists and one gastroenterologist who subjectively classified the distributation (peripheral, central, diffuse) and amount (no, minimal, moderate and strong) of now pattern in each sonographic examination. Histologic verification was obtained ii, all liver lesions except in hemangiomas, where MR-imaging and in one FNH, where scintigraphy was regarded sufficient prove. Results: Overall, power Doppler sonography was superior to color Doppler sonography in 22 liver lesions. With power Doppler previously visible flow was enhanced in 9 patients in 13 lesions flow was detected, which was not seen before. 31 tumours (12 hemangiomas, 2 inflammatory lesions, 2 focal fatty infiltration, 1 FNH, 8 metastases, 6 HCCs) did not show a flow signal in either mode. Flow signals were detected with conventional color Doppler/power Doppler in 0/1 hemangioma centrally: and peripherally, 1/2 hemangiomas only peripherally, 0/2 hemangiomas only centrally, 1/0 FNH central and peripherally, 1/0 FNH only peripherally 1/0 FNH only centrally, 3/0 metastases centrally and peripherally, 1/3 metastases only peripherally; 1/2 metastases only centrally, 6/0 HCCs centrally and metastases only peripherally; 1/2 metastases; only centrally, 6/0 HCCs centrally and peripherally, 4/0 HCCs only peripherally, 3/1 HCCs only centrally. Conclusion: Power Doppler sonography is more sensitive than conventional color Doppler sonography in the depiction of tumor vascularity. Intratumoral flow signals favour a malignant tumour. The absence of now signals is a frequent finding in benign lesions but do not rule out malignancy.