Cross-section imaging with M-mode as an alternative method for the measurement of brachial artery flow-mediated vasodilation.

Abstract

PURPOSE: Endothelial dysfunction is well known as a risk marker for initiation and progression of atherosclerosis. Flow-mediated vasodilation (FMD) of the brachial artery induced by postischemic forearm hyperemia is a widely used noninvasive method for evaluating endothelial function. M-mode ultrasonography offers high spatial and temporal resolution and is therefore suitable for diameter measurement of pulsatile vessels. We intended to compare FMD values obtained by M-mode on cross-section images and by the conventional method, ie, measurement with B-mode ultrasonography on longitudinal images. METHODS: We recruited 37 subjects (19 women, mean age: 48.3 ± 15.2 years; range: 23-71 years) in whom we measured the brachial artery diameters at baseline and at maximum dilation after forearm ischemia. FMD was calculated as the percentage of postischemic dilation. RESULTS: Baseline (3.92 ± 0.72 versus 3.91 ± 0.58 mm; p = 0.97) and maximal dilated diastolic diameter (4.26 ± 0.76 versus 4.23 ± 0.61 mm; p = 0.84), FMD (8.98 ± 3.84 versus 8.14 ± 1.99%; p = 0.84), and time to maximum dilation (48.7 ± 9.0 versus 49.3 ± 6.4 seconds, p = 0.64) were not different between the two methods. CONCLUSIONS: M-mode brachial artery diastolic and systolic diameter measurement is feasible, suitable, and accurate for the assessment of FMD without the need for electrocardiography.