Effect of concentration of contrast medium on coronary CT angiography.

OBJECTIVE To compare concentration of contrast medium for vascular opacification at ascending aorta using retrospective reconstruction of coronary CT angiography. STUDY DESIGN Retrospective study. MATERIAL AND METHOD Eighty-four patients undergoing coronary CT angiography with 16 multi-detector rows at Siriraj Hospital between September 2003 and July 2004 were included in this study. The patients were categorized into two groups. The first group was administrated with 350 mgl/ml contrast medium and the second group was administrated with 370 mgl/ml contrast medium. The total amount of contrast medium was about 140 ml (20 ml for timing bolus and 120 ml for CT angiography) in both groups. The CT density on peak contrast administration at ascending aorta was measured and compared between the two groups. RESULTS The mean density at ascending aorta in 350 mgl/ml and 370 mgl/ml were 362.96 HU (SD 67.53) and 354.44 (SD 59.39), respectively. There was no statistically significant difference in mean density at the ascending aorta between the two groups. CONCLUSION Administration of contrast medium with different concentrations of 350 or 370 mgl/ml showed no statistical difference on enhancement of the ascending aorta in coronary CT angiography (p < 0.05).