Liver tumor imaging: current concepts.

With the increasing availability of curative surgical techniques for primary and secondary hepatic neoplasms, the tasks for clinical imaging of patients suspected of having liver cancer have become more exacting. Detection of tumor, differential diagnosis of individual nodules, and mapping the anatomic extensions of malignant disease are now required routinely. Related and unrelated liver substrate abnormalities such as cavernous hemangioma and focal fatty deposits are often discovered in these patients and must be differentiated from metastatic deposits. Moreover, modern imaging methods frequently display tiny nodules (less than 1 cm) that often prove difficult to adequately characterize (micrometastases vs other kinds of lesions). The most sensitive imaging techniques are CT after arterial portography and intraoperative sonography, but because of their invasiveness, these are reserved exclusively for cancer staging. For primary screening, MR imaging is increasingly preferred over CT because of its superiority in discriminating hemangiomas and cysts from metastases without the need for iodinated contrast material.