Image quality and radiation dose from single heart beat CT coronary angiography performed with a 320-detector CT scanner

Objective:To evaluate the image quality and radiation dose for patients with heart rate(HR) below 65 beats per minnute(bpm) with prospective electrocardiogram(ECG)-triggering using 320-detector CT scanner. Methods:A total of 241 patients suspected or known coronary artery disease,who underwent coronary CT angiography using 320-detector CT scanner,were assigned three groups:group A(122 cases) with HR65 bpm;group B(62 cases),with HR from 65 to 80 bpm;and group C(57 cases) with HR≥80 bpm.Following data acquisition,dataset with best phase were transferred to a workstation for further processing by means of VR,MPR,CPR.Based on 4-point likert scale,image quality was scored and categorized.Chi-square test was made for grade of image quality.Kruskal-Wallis test was performed to compare radiation dose.Results:Significant difference was found for good and excellent image quality among three groups(x2=87.46,P0.05).No significant difference was found for the rate of assessable image.(x2=3.99,P0.05).A sum of five segments of coronary artery were found not to be assessable.The effective dose of group A,B and C was on average(3.79±2.32) mSv,(11.60±5.05) mSv and(16.52±6.36) mSv,a significant difference showed in them(x2=149.11,P0.05).A significant difference was found between group A and B,A and C,B and C(Z=-11.39,-8.47,-4.32,P0.017).Conclusion:Image quality is excellent and low radiation dose,which can be achieved for patients with HR65 bpm using 320-detector CT scanner.