In vivo validation of MR velocity imaging.

Calculations of left ventricular stroke volume obtained by summing the areas of multiple contiguous transverse magnetic resonance (MR) slices in systole and diastole using a spin echo sequence have been compared in 10 healthy volunteers with the stroke output derived from velocity maps in the ascending aorta using a field even-echo rephasing sequence. The results gave a correlation coefficient of 0.97 (p less than 0.001) and a standard error of estimate of 3.2 ml. Velocity maps have also been obtained in the pulmonary artery, the descending aorta, and the superior vena cava. The accuracy of this technique and the theoretical limitations of MR measurements have implications for the earlier detection of atheroma in the coronary and other arteries.