Hepatic imaging with iodinated nanoparticles: a comparison with iohexol in rabbits.

RATIONALE AND OBJECTIVES: We evaluated the efficacy of a particulate computed tomography (CT) contrast agent in an animal model of focal liver disease. METHODS: Ethyl ester of diatrizoic acid (EEDA) is an iodinated (89 mg I/ml) nanoparticulate (200 nm) contrast agent intended for intravenous use that is currently undergoing preclinical testing in our laboratory. Focal liver abscesses were created in 11 New Zealand White rabbits. Iohexol and EEDA were administered to each animal on different days. CT scanning was performed at intervals following contrast agent administration. Liver and abscess enhancement were measured and compared. Dynamic imaging experiments in normal animals were also performed using both agents. RESULTS: EEDA resulted in significantly greater enhancement of the liver and liver-to-abscess contrast than did iohexol at all time points beyond 5 min at approximately 25% of the total iodine load. During dynamic imaging, liver and aortic enhancement were greater with EEDA than with iohexol, except during a 20- to 40-sec period immediately following contrast agent administration. CONCLUSION: EEDA is superior to iohexol for imaging liver abscesses. Our results suggest that liver-directed agents such as EEDA may prove to be more efficacious than currently available extracellular agents designed for liver CT scanning.