Liver tumor imaging is the paradigm of the dilemma of diagnostic decision-making in the current era of abundant high technology. In part, this is a reflection of the multiplicity of imaging techniques now in wide use worldwide. These include ultrasound (US), radionuclide scintigraphy (RNS), computed tomography (CT), magnetic resonance imaging (MRI), and techniques especially designed for staging the extent of known liver cancer, such as computed tomography during arterial portography (CTAP) and intraoperative ultrasound (IOUS). Most authorities concede that CT scanning is the single test most closely fitting the designation "gold standard" for liver tumor imaging, although MRI, a less mature technique, is already preferred by some. Local factors profoundly influence the selection and sequence of imaging studies, including available equipment, radiologic skills, institutional interests, and especially the specific clinical circumstances of the patient. Thus, diagnostic algorithms or decision trees for sequential imaging workup of liver tumor suspects tend to be somewhat institution specific. Cancer 67:1189-1195.1991.
N THE CONTEXT of this conference, this discussion will I be limited to radiologic evaluation of liver cancer, both primary and secondary. Spleen and pancreas will be deferred to other authors.
In 1989 it was estimated that there were nearly 150,000 new cases of colorectal carcinoma diagnosed in the United States.' Of these, approximately 40%, or 60,000 patients, will ultimately prove to have liver metastases. Worldwide, primary hepatocellular carcinoma is an endemic disorder in many underdeveloped countries and in southeast Asia and sub-Saharan Africa accounts for one-third of all malignant neoplasms.
Among the most significant therapeutic advances in the management of primary and second liver malignancy are the continued evolution of aggressive surgical techniques. It is now estimated that as many as one-fourth of all primary and secondary liver cancers are potentially resectable for cure. In patients with metastatic colorectal carcinoma, resections in patients with three or fewer secondary deposits have yielded a 20% to 40% 5-year survival