Quantitative evaluation of image quality about taking nitroglycerin on 64-slice spiral coronary angiography

Objective: To quantitatively evaluate the influence of taking nitroglycerin on the lumen diameter of coronary arteries and segments visualized on 64-MSCT angiography. Methods: Two hundred patients were recruited in this study: half of the patients (group A) received nitroglycerin, the other half (group B) served as the control group and did not receive nitroglycerin. CT angiography was performed using 64-MSCT scanner with ECG modulated mA turned on. MPR, MIP, CPR and VR images in best phase were used to display coronary arteries. Lumen diameters of each coronaries were measured from 10 different slices and number of segments visualized were documented. All the data was analyzed using t test. Results: For right coronary artery (RCA), in proximal, middle and distant segments, the lumen diameters in group A increased 0.29,0.17,0.11 mm (8.0%, 5.0%, 4.0%) than group B, respectively. For left anterior descending branch (LAD), the lumen diameters increased 0.40, 0.23, 0.10 mm (11.0%, 8.0%, 4.7%) respectively. For left circumflex (LCX), the lumen diameters increased 0.42,0.35,0.12 mm (13.5%, 12.5%,5.5%) respectively. For left main artery (LMA), the lumen diameters increased 0.31 mm and the increased percentage was 7.8%. The visualized segments were significantly more in group A than in group B. The percentage of increased number was 83% for RCA, 80% for LAD, and 113% for LCX, respectively. In proximal, middle segments of LAD and LCX, together with RCA and LMA, the diameters were statistically different between group A and group B (t=5.35,3.58,5.29,4.64,3.86 and 3.74, P< 0.01). In distant segments of LAD, LCX and RCA, together with middle segments of RCA, there were differences in diameters between group A and group B (t=2.35,2.14,2.58,2.13,P<0.05). Conclusion: Using nitroglycerin can significantly improve the image quality by expanding the diameter of coronary arteries and increasing the number of visualized segments on 64-MSCT coronary angiography. (authors)