Dynamic helical CT as a novel technique for diagnosing hepatic perfusion disorders

Perfusion disorders of the liver have seldom been studied by computed tomography (CT). Recent new-generation helical CT by speeding up the scanning time proves it is possible to evaluate these disorders. The purpose of this study is to demonstrate the various patterns of hemodynamic change of the liver in both normal and diseased status by dynamic helical CT technique.

In a period of 1 year, about 1,000 patients received dynamic helical CT examination of the liver due to either clinical suspicion of liver lesions or liver lesions of unknown nature. The examination was performed with a Picker PQ 2000 CT scanner. In total, 100 cc of iodinated contrast agent was injected at a rate of 3.5 cc per second. Two sets of images were acquired at 22 seconds and 75 seconds after the initiation of the contrast injection. Different patterns of hemodynamic change were found and the etiologies and mechanisms were investigated.

Sixty-two cases were found to have perfusion disorder of the liver. Thirty cases were associated with tumors such as hepatoma (17), hemangioma (4) and hepatic metastasis (3). The other 32 cases were non-tumor associated. The perfusion disorders appeared due to liver cirrhosis, anatomic variant, iatrogenic injury, liver abscess, etc. The mechanisms for these perfusion disorders were classified as portal vein compression or thrombosis, arterioportal shunting, hepatic artery encasement, local hyperremic change, aberrant blood supply, steal effect, hepatic venous outflow obstruction, etc. These disorders presented as subcapsular, focal nodular, wedge-shaped, segmental, lobar, or even diffuse in shape and distribution.

Dynamic helical CT opens a new window for demonstrating and understanding various hepatic perfusion disorders which reflect the hemodynamic change of the liver in both normal and diseased conditions.