Cardiac CT검사에 있어서 심박동수 및 그 변화가 Image Quality 및 Optimized Reconstruction Window Phase에 미치는 영향에 대한 평가

Evaluation of Influence on Image quality and Optimized reconstruction window by Heart rate and it’s Variation on Cardiac CT study.

Purpose To investigate the influence on image quality of coronary CT angiography by heart rate and its variation. Material and Methods We studied 119 patients who had undergone coronary CT angiography using a heart rate responsive gating algorithm and adaptive multi-cycle reconstructions. Ranges of heart rate(bpm: beats per minutes) before the scan were classified as follows: 60 bpm < (n= 28), 61-70 bpm(n=35), 71-80 bpm (n=26), 81-90 bpm(n=l6), 91-100 bpm(n=9), 100 bpm > (n=5). Two radiologists rated the image quality as follows; 4: excellent, 3: good, 2: fair, 1: bad. Influence on image quality by heart rate and its variation during the scan was analyzed. Results Variations of heart rate were showed as follows: 0-10 bpm < (n=86 patients), 11-20 bpm(n=26), 20 > bpm(n=7). High variation of heart rate showed more poor image quality(0-10 bpm: 3.550.62, 11-20 bpm: 3.120.52, 20 > bpm: 2.120.64). Image quality was decreased as heart rate was higher(60< bpm: 3.570.7, 61-70 bpm: 3.260.87, 71-80 bpm: 3.460.8, 81-90 bpm: 3.040.64, 91-100 bpm: 3.22 0.97, 100> bpm: 3.000.71), but image quality was more affected by the variation of the heart rate than by the higher heart rate. The selection of an optimized reconstruction window is mainly affected by the heart rate, not by its variation. There is tendency for systolic phase(50%) to have a superior image quality than diastolic phase(75%) at higher heart rates(above 70 bpm) regardless of its variation. Conclusion We suggest that the variation of heart rate during the scan is important factor on image quality of coronary CT angiography. But it does not affect to the selection of an optimized reconstruction window.