FOCAL FATTY INFILTRATION - A CAUSE OF NONTUMOROUS DEFECTS IN THE LEFT HEPATIC LOBE DURING CT ARTERIAL PORTOGRAPHY

Objective: The purpose of this work was to determine the frequency and significance of characteristic nontumorous low attenuation defects found in the left hepatic lobe during CT arterial portography (CTAP). Materials and Methods: Eighty CTAPs performed over a 17 month period were retrospectively reviewed to identify nonsegmental low attenuation defects adjacent to the falciform ligament, gallbladder, or porta hepatis. Twenty-four separate defects were present in 14 of 80 (18%) patients. Cases in which a defect was present were compared with MR, surgical findings, and pathology reports. Results: The defects were oval or triangular in shape with a mean maximum diameter of 1.7 cm (range 1-5 cm). None of these defects were identified on MR in the 12 patients who underwent T1, T2, and STIR MR; however, 3 showed dropout of signal on chemical shift MR, suggesting fatty infiltration. In the 12 patients who underwent surgery, no lesion was shown to represent tumor. Two intraoperative biopsies of the area of the defects showed fatty infiltration. Conclusion: Nontumorous low attenuation defects adjacent to the gallbladder, falciform ligament, or porta hepatis are a pitfall of CTAP and can be associated with focal fatty infiltration, as well as decreased perfusion due to technical factors or a variation in hepatic vascular supply.