A novel method for assessing arterial endothelial function using phase contrast magnetic resonance imaging: vasoconstriction during reduced shear.

We investigated whether endothelial-dependent arterial constriction during reduced shear can be measured using phase contrast magnetic resonance imaging (PCMRI). A cross-section of the femoral artery was acquired during a 5-minute distal occlusion in 33 subjects. Systolic shear rate and radius were measured from the velocity profile via a best-fit parabola. Systolic shear rate decreased immediately after cuff inflation (404 +/- 78 to 233 +/- 75 sec(-1) p < .0001). Radius decreased at 2 min into inflation (3.52 +/- .41 to 3.43 +/- .42 mm, p < .0001). In conclusion, arterial constriction during reduced flow can be measured using PCMRI. This new method may add important information toward a comprehensive evaluation of endothelial function.