Transient Hepatic Attenuation Differences - Pictorial Essay

The liver has a dual blood supply (70% portal vein, 30% hepatic artery) with compensatory relationships between the two inflows: arterial flow increases when portal flow decreases. This flow occurs as a result of communications among main vessels, sinusoids, and peribiliary venules that open in response to nervous and humoral factors. Transient hepatic attenuation differences are areas of parenchymal enhancement visible during the hepatic arterial phase on helical CT [1, 2]. Because of the wide diffusion of hepatic arterial phase evaluation, transient hepatic attenuation differences are now rather frequent. In a previous study from our group, the differences were identified on 130 (13%) of 988 helical CT scans of the liver [3]. Transient hepatic attenuation differences have been associated with a large variety of liver disorders [1–3]. Our article aims to show the range of these arterial phenomena in a comprehensive diagnostic organization correlating morphology with etiology and pathogenesis. Transient hepatic attenuation differences