Real time assessment of the endothelial function

Endothelial dysfunction is a systemic marker of cardiovascular disease and it can predict the development of overt atherosclerosis. An ultrasound approach can be used to measure the endothelial function for non-invasive in-vivo applications. Endothelium-dependent relaxation can be assessed by continuously measuring the brachial artery diameter change in response to occlusion and re-flow. The main goal of this work is the development of an automatic and operator-independent procedure which is able to locate the walls and to record, in real-time, the diameter of the brachial artery. The localization procedure is based on the computation of the centre of mass of the first-order absolute moment (FOAM). Important features of this operator allow parallel and real-time implementation of the contour-tracking procedure on digital signal processor (DSP) architectures. Methods derived from the standard regularization theory are also used to cope with noise, and each wall is approximated with a straight line. The procedure was quantitatively assessed by computing the linear regression between the diameter estimated by the system and the diameter estimated by an expert.