Fig. 4
Coronary distensibility of a healthy volunteer measured with coronary MR angiography (MRA). Images in a 26-year-old female healthy volunteer. Peripheral blood pressure was 108/68 mm Hg (pulse pressure = 40 mm Hg). The axial original whole-heart MR images at diastole and systole show the difference in lumen size of right coronary artery (RCA) (yellow arrows), left anterior descending artery (LAD) (blue arrows),and left circumflex coronary artery (LCX) (green arrows). Coronary MRA images show remarkable coronary distensibility in RCA (lumen area 5.89 mm2 at diastole and 7.80 mm2 at systole, coronary distensibility index (CDI) = [(7.80 − 5.89)/(5.89/40)] × 1000 = 8.11 mm Hg−1), LAD (lumen area 7.01 mm2 at diastole and 9.73 mm2 at systole, CDI = [(9.73 − 7.01)/(7.01/40)] × 1000 = 9.70 mm Hg−1) and LCX (lumen area 5.02 mm2 at diastole and 6.93 mm2 at systole, CDI = [(6.93 − 5.02)/(5.02/40)] × 1000 = 9.51 mm Hg−1)