Prediction of Aortic Enhancement on Coronary CTA Images Using a Test Bolus of Diluted Contrast Material

Abstract

The purpose of our study was to compare test bolus techniques using undiluted or diluted contrast material for their ability to predict aortic enhancement on coronary computed tomographic angiography (c-CTA) images. We divided 200 consecutive patients who underwent c-CTA on a 64-MDCT scanner into two groups. In group A (n=100), we used a test bolus of undiluted contrast material and in group B (n=100), the contrast material was diluted. The injection volume was body weight×0.2 (contrast material 100%) in group A and body weight×0.7 (contrast material 30%, saline 70%) in group B. We then compared the CT number in the ascending aorta on c-CTA images obtained with undiluted and diluted contrast media to the CT number on c-CTA images. The mean CT number in the ascending aorta was significantly higher in group B than group A (217.1 vs. 157.4HU, P<.001). There was a significant difference in the correlation between the CT number of the ascending aorta on c-CTA images and on images acquired with the test bolus using undiluted or diluted test bolus (P<.001). In group B, the correlation had a strong positive linear relationship (r=0.72, P<.001), whereas in group A the positive linear relationship was weak (r=0.36). The test bolus with diluted contrast material was useful for predicting aortic enhancement before c-CTA scanning.