Contrast-enhanced US Approach to the Diagnosis of Focal Liver Masses

Abstract

This easy-to-follow algorithm describes a step-by-step approach to differentiating benign from malignant liver lesions, characterizing benign liver tumors accurately on the basis of their specific arterial enhancement patterns, and helping distinguish hepatocellular and nonhepatocellular malignancies with assessment of the intensity and timing of washout. Focal liver lesions are commonly encountered and often demonstrate nonspecific findings at initial imaging. Although most incidentally discovered liver lesions are benign, their noninvasive diagnosis is necessary, especially if they are large or atypical. Imaging characterization of focal liver lesions and exclusion of malignancy are of prime importance, particularly in high-risk populations. Contrast agent–enhanced ultrasonography of liver lesions is both accurate and reproducible for evaluation of benign and malignant liver tumors. Use of an imaging algorithm and a controlled sonographic technique, including dedicated arterial phase cine imaging and imaging every 30 seconds in the portal venous phase and the delayed (or late) phase, is essential for accurate characterization. This algorithmic analysis of focal liver lesions focuses first on the determination of malignancy by imaging the portal venous phase and the late phase; washout in these phases correlates with a malignant tumor, and sustained enhan...