Computed Tomography of Experimental Liver Abscesses Using a New Liposomal Contrast Agent

RATIONALE AND OBJECTIVES Evaluation of computed tomographic enhancement characteristics of a new liposomal contrast agent (liposomal iodixanol [LI] in a pyogenic liver abscess model in 17 rabbits. METHODS Eight to 14 days after abscess induction (Escherichia coli), density-time curves were calculated for regions of interest in liver, abscess wall and center, spleen, portal vein, abdominal aorta, inferior vena cava, and kidney. Images were obtained every minute between 1 and 10 minutes, every 5 minutes between 15 and 60 minutes, and 75 minutes after 200 mg/kg LI application (group A: 7 rabbits) and after 600 mg/kg iopentol application (group B: 10 rabbits), and 90, 105, and 120 minutes after LI. RESULTS The abscess wall-liver contrast after LI lasted from 10 to more than 120 minutes with a maximum of 30 Δ Hounsfield Units (HU) at 45 minutes. For iopentol, the abscess wall-liver contrast lasted from 2 to 7 minutes with a maximum of 8 Δ HU at 5 minutes. The abscess wall-center contrast after LI lasted from 1 to more than 120 minutes with a maximum of 122 Δ HU at 40 minutes. For iopentol, the abscess wall-center contrast lasted from 1 to 75 minutes with a maximum of 79 Δ HU at 1 minute. The liver-portal vein contrast after LI lasted from 1 to more than 120 minutes with a maximum of 100 Δ HU at 20 minutes. For iopentol, the liver-portal vein contrast lasted from 1 to 8 minutes with a maximum of 38 Δ HU at 2 minutes. An abscess wall was detected in a higher percentage of the LI images (86% LI, 56% iopentol), and images in the LI group correlated better with histopathology. CONCLUSIONS The diagnostic value of LI exceeds that of iopentol in terms of overall abscess contrast and duration of the diagnostic interval. The higher hepatic vessel contrast allows better abscess localization.