Current value of sonography for the characterization of focal liver lesions Incidental focal lesions are frequently discovered during sonographic exploration of the liver. Solid lesions remain often questionable, particularly in oncological or infectious patients. Doppler exploration generally doesn't help and other modalities, such as CT, MRI or even biopsy are necessary to definitively categorize the lesion. Ultrasound contrast agents associated with contrast detection ultrasound mode give the opportunity to follow the blood flow until the capillary level. Thus the dynamical behavior of blood flow in tissue is now observable with US, as it was previously with CT or MRI alone. The aim of this paper is to review the actual knowledge about the characterization of focal liver lesions with sonographic dynamic enhancement and to discuss the advantages and limitations of this particular technique.