Analysis of the heart rate and its variation affecting image quality and optimized reconstruction window in retrospective ECG-gated coronary angiography using multidetector row CT

It is clinically important to examine the effect of the heart rate and its variation on the image quality and selection of the optimized window in coronary angiography using multidetector row CT (MDCT). This study performed contrast-enhanced coronary angiography using MDCT on 83 patients. Fifty-two cases with information on the heart rate available were enrolled in this study. The effect of heart rate and its variation were systemically analyzed. Two radiologists rated the image quality as follows: 4-excellent; 3-good; 2-fair; 1-bad. Cardiac cycle windows at 40% and 70% were routinely selected for image reconstruction. The optimized window was rated as 1 when a 40% reconstruction had a better quality than the 70% reconstruction, as 2 when the 40% reconstruction was the same as the 70% reconstruction, and as 3 when the 70% reconstruction was better than the 40% reconstruction. The image quality was more affected by a variation of the heart rate than by the high heart rate. The selection of the optimized reconstruction window for a good image quality was mostly affected by the heart rate and there was a tendency for the 40% phase reconstruction to have a better image quality than the 70% reconstruction at higher heart rates.