Hepatic CT enhancement: comparison of ionic and nonionic contrast agents in the same patients.

ABSTRACT

PURPOSE: The authors prospectively compared the effects of ionic and nonionic contrast agents on hepatic enhancement at computed tomography (CT) in the same patient population. MATERIALS AND METHODS: Forty-six patients underwent abdominal CT with either ionic or nonionic contrast agents. At 6-month follow-up, the alternative agent was used. Pre- and postcontrast attenuation values of liver and vessels were obtained; enhancement and postinjection time of each image were recorded. The area under a computer-generated enhancement-time curve was calculated as a means of measuring enhancement over time. Mean liver enhancement with ionic and nonionic contrast agents was compared. RESULTS: Mean hepatic enhancement with ionic contrast material was greater than with nonionic contrast material at all time intervals through 90 seconds after injection. The difference was statistically significant from 61 to 70 seconds. Mean peak liver enhancement for ionic and nonionic contrast agents was nearly identical (59 and 58 HU, respectively), but mean time to peak hepatic enhancement with nonionic contrast agent was greater by 10 seconds. CONCLUSION: These results indicate that ionic contrast agent may effect greater liver tumor conspicuity.