SIMULTANEOUS ULTRASOUND ASSESSMENT OF BRACHIAL ARTERY SHEAR STIMULUS AND FLOW-MEDIATED DILATION DURING REACTIVE HYPEREMIA

In flow-mediated dilation (FMD) studies, brachial artery diameter changes due to reactive hyperaemia are typically measured through manual or automatic analysis of high resolution B-mode images while the stimulus of diameter change, i.e., the flow change, is qualitatively estimated by measuring the mean velocity in the vessel and assuming a parabolic velocity profile. This article describes an experimental approach to simultaneously measure the wall shear rate (WSR) and the diameter variations, through multigate spectral Doppler and B-mode image processing, respectively. By using an ultrasound advanced open platform (ULA-OP), experimental results from the brachial arteries of 15 presumed healthy volunteers have been obtained. The mean increments during reflow against baseline were 105% +/- 22% for the peak WSR and 8% +/- 3% for the FMD. The mean time interval between the WSR peak and the beginning of plateau of diameter waveform was 38 +/- 8 s. The results confirm that in young healthy subjects the postischemic vasodilation of brachial artery is largely correlated to the WSR increase. (E-mail: piero.tortoli@unifi.it) (C) 2011 World Federation for Ultrasound in Medicine & Biology.