Radionuclide liver scans in tumor detection: current concepts

Because of the frequency of spread of tumors arising elsewhere to the liver, hepatic evaluation plays a key role in planning therapy. Dynamic radionuclide transit studies depend upon the dual blood supply of the liver (hepatic artery and portal vein) and can be a useful prelude to static imaging, as most intrahepatic tumors have an hepatic arterial blood supply. Since most tumors do not have the ability to accumulate a radioactive colloid, static views are usually obtained after injection of particulates, which are accumulated by the reticuloendothelial system. A gross defect on the radiocolloid scan simply indicates the presence of an intrahepatic abnormality, but does not identify the nature of the lesion. The possible role to be played by use of additional radiopharmaceuticals, with different properties, in identifying the intrahepatic process is discussed. Other uses of liver scans, such as in evaluating the response of known intrahepatic lesions to therapy, are pointed out.