Enhancement effects of a hepatocyte receptor-specific MR contrast agent in an animal model

The enhancement characteristics of the liver and spleen produced by a hepatocyte-specific magnetic resonance imaging agent, an arabinogalactan-coated ultrasmall superparamagnetic iron oxide derivative, BMS 180550, were evaluated. Both heavily T1- and T2-weighted sequences were used. Imaging was performed in the farm pig model, as a function of contrast agent concentration (5, 10, and 20 mumol of iron per kilogram) and delay (immediate, 0.5, 2.5, 5.0, 7.5, and 9.0 hours) after bolus injection of BMS 180550. BMS 180550 provided excellent contrast enhancement characteristics by producing marked positive enhancement with T1-weighted sequences and marked negative enhancement with T2-weighted sequences. The T1-weighted enhancement immediately after contrast agent injection was of greater magnitude in the spleen (329% +/- 83) than in the liver (66% +/- 16). Postcontrast negative enhancement with T2-weighted sequences was largely hepatocyte specific at 5 and 10 mumol/kg but was also seen within the spleen at 20 mumol/kg. The authors discuss the possible mechanisms that produce these changes and conclude that 10 mumol/kg BMS 180550 is near the optimum dose for maximizing the enhancement properties of this agent with all sequences in the farm pig.