Arterial enhancement at abdominal CT angiography - Low- versus high-osmolality contrast media

Purpose: To evaluate the effects of contrast media pharmokinetic difference s on aortic enhancement at abdominal CT angiography and to determine whethe r these effects are of clinical relevance. Material and Methods: Two hundred and twelve patients referred for abdomina l CT angiography were included in the study. All abdominal CT angiograms we re performed with the same parameters (collimation 3 mm, pitch ratio 1.7, s can delay 30 s) after i.v. injection of 120 ml of contrast medium at 3 ml/s . After randomization, patients received either iobitridol 300 (low-osmolar , 300 mg I/ml), iobitridol 350 (low-osmolar, 350 mg I/ml) or ioxithalamate 350 (high-osmolar, 350 mg I/ml). The time attenuation curves obtained with the three contrast media were compared. Results: The time attenuation curve obtained with ioxithalamate 350 was not parallel to those obtained with iobitridol 300 and iobitridol 350. Mean pe ak enhancements obtained with iobitridol 350 and ioxithalamate 350 were not significantly different but iobitridol 350 provided higher mean peak enhan cement than iobitridol 300. Mean delays of the peak enhancements were the s ame with the three contrast media. After peak enhancement, the decrease of aortic opacification under a selected threshold of 200 HU was significantly slower with iobitridol 350 than with iobitridol 300 and ioxithalamate 350, whereas iobitridol 300 and ioxithalamate 350 showed no significant differe nces. Conclusion: For a given iodine concentration, low-osmolality contrast media provide longer aortic opacification and may be recommended for CT angiogra phy when long acquisition times are needed.