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

BACKGROUND/AIMS: Perfusion disorders of the liver have seldom been studied by computed tomography (CT). Recent new-generation helical CT by speeding u p 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. METHODOLOGY: In a period of 1 year, about 1,000 patients received dynamic h elical CT examination of the liver due to either clinical suspicion of live r lesions or liver lesions of unknown nature. The examination was performed with a Picker PQ 2000 CT scanner. In total, 100cc of iodinated contrast ag ent was injected at a rate of 3.5cc per second. Two sets of images were acq uired at 22 seconds and 75 seconds after the initiation of the contrast inj ection. Different patterns of hemodynamic change were found and the etiolog ies and mechanisms were investigated. RESULTS: Sixty-two cases were found to have perfusion disorder of the liver . Thirty cases were associated with tumors such as hepatoma (17), hemangiom a (4) and hepatic metastasis (3). The other 32 cases were non-tumor associa ted. The perfusion disorders appeared due to liver cirrhosis, anatomic vari ant, iatrogenic injury, liver abscess, etc. The mechanisms for these perfus ion disorders were classified as portal vein compression or thrombosis, art erioportal shunting, hepatic artery encasement, local hyperremic change, ab errant blood supply, steal effect, hepatic venous outflow obstruction, etc. These disorders presented as subcapsular, focal nodular, wedge-shaped, seg mental, lobar, or even diffuse in shape and distribution. CONCLUSIONS: Dynamic helical CT opens a new window for demonstrating and un derstanding various hepatic perfusion disorders which reflect the hemodynam ic change of the liver in both normal and diseased conditions.