Transient hepatic attenuation differences and focal liver lesions: sump effect due to primary arterial hyperperfusion.

Objective: To analyze at computed tomography (CT) examination the "sump effect," a particular type of transient hepatic attenuation differences, related primarily to an increase in arterial flow without any accompanying decrease in portal flow.

Methods: We retrospectively evaluated all biphasic upper abdomen CT examinations (1283 in 807 patients) performed from the year 2003 to the year 2006 and selected and organized those with at least 1 transient hepatic attenuation differences. Of these, we enrolled patients with lobar/multisegmental arterializations surrounding focal lesion(s), without CT portal hypoperfusion signs, in the study group.