ECG-gated multislice CT(MSCT)now supports not only morphological but also functional diagnosis. In order to improve accuracy in the functional analysis of cardiac motion, it is important to depict the endocardial and epicardial contours. The present study was conducted to evaluate a method in which contrast medium and physiological saline solution(saline)are injected simultaneously, and the iodinated contrast medium concentration is varied in a stepwise manner(multi-stage injection)or continuously(cross injection). The results showed that the cross-injection method exhibited small differences in myocardial CT values between the right and left heart and was thought to be effective for automatic region extraction of the cardiac chambers and myocardium. However, cross-injection requires saline and contrast medium to be injected in equal volumes, necessitating a higher injection speed. Therefore, a newly developed trapezoidal cross-injection method was included in the study as an improved method. The results showed that trapezoidal cross injection provided high CT values. The relationship between the patient's body weight and the amount of iodinated contrast medium used also was investigated, and a negative correlation was observed for all three injection methods: multi-stage injection(r=0.63), cross injection(r=0.54), and trapezoidal cross injection(r=0.8). The trapezoidal cross-injection method showed the strongest correlation.
