Measurement of coronary artery flow reserve by magnetic resonance velocity mapping in the aorta.

Coronary artery flow occurs predominantly in diastole via retrograde flow in the ascending aorta, some of which supplies the coronary arteries while the remainder recirculates in the ascending aorta. We used magnetic resonance velocity mapping to measure global coronary artery diastolic flow in the ascending aorta. In eight normal subjects and in four patients with possible ischaemic heart disease but with normal perfusion scans, the mean coronary flow reserve (CFR) was 269 ml/min. CFR was zero in seven patients with coronary artery disease. We have shown that CFR can be measured non-invasively with this technique.