OBJECTIVE Computed tomographic (CT) enhancement of the liver, liver abscess, spleen, and major vessels was investigated between 2 and 48 hours after intravenous administration of perfluorooctylbromide (PFOB emulsion) in an animal model of 63 rabbits. METHODS Twenty-one animals received 3 g/kg PFOB as a fast bolus injection. Using a slow infusion rate, the same number of animals received either the same dose (3 g/kg) or half the dose (1.5 g/kg). RESULTS Vascular enhancement was best after bolus injection of 3 g/kg emulsion. The density peak occurred after 2 hours. A continuous enhancement of approximately 100 Hounsfield units (HU) was observed up to 24 hours in the animals receiving 3 g/kg, independent of the injection velocity. A density peak of 70 HU was found 2 hours after the infusion of 1.5 g/kg. The density peak of the liver, the spleen, and the abscess wall was observed 48 hours after emulsion administration in all groups receiving 3 g/kg. The peak was approximately 150 HU for the liver, 400 HU for the spleen, and 150 HU for the abscess wall. In animals receiving only 1.5 g/kg perflubron, the peak density of the abscess wall was 132 HU after 12 hours, approximately 80 HU for the liver between 2 and 48 hours, and approximately 280 HU after 48 hours for the spleen. CONCLUSIONS PFOB emulsion produces the highest vascular enhancement within the first 2 hours after the bolus injection of 3 g/kg. For spleen and abscess wall imaging, even the relatively low dose of 1.5 g/kg produced a satisfactory enhancement level for a significant length of time, whereas liver enhancement was best after administration of the higher dose.