Bi-plane imaging for a robust assessment of Flow Mediated Dilation

Flow Mediated Dilation (FMD), a biomarker of endothelial function, consists of monitoring the brachial artery response to a transient occlusion. During this exam, the wall shear stress (stimulus) and diameter change (effect) should be simultaneously measured. Typically, both parameters are evaluated through the vessel longitudinal view, and the shear stress is estimated through the measurement of the centerline flow velocity, assuming a parabolic profile. Since the exam is relatively long, it is likely impaired by possible movements of the patient's arm. In this work, we have connected a 256-element sparse spiral array to the ULA-OP 256 scanner to implement a bi-plane imaging modality that, by exploiting both cross and longitudinal arterial views, allows reliable simultaneous measurements of diameter and flow profile. The improved robustness achieved by tracking the diameter on the cross-section view was demonstrated through phantom experiments and a preliminary in-vivo test.