Automatic measurement of end-diastolic arterial lumen diameter in ARTSENS

Over past few years, we are developing a system for facilitating large scale screening of patients for cardiovascular risk-arterial stiffness evaluation for noninvasive screening (ARTSENS). ARTSENS is an image-free device that uses a single element ultrasound transducer to obtain noninvasive measurements of arterial stiffness (AS) in a fully automated manner. AS is directly proportional to end-diastolic lumen diameter (D<inf>d</inf>). Multilayered structure of the arterial walls and indistinct characteristics of intima-lumen interface (ILI) makes it quite difficult to accurately estimate D<inf>d</inf> in A-mode radiofrequency (RF) frames obtained from ARTSENS. In this paper, we propose a few methods based on fitting simple mathematical models to the echoes from arterial walls, followed by a novel method to fuse the information from curve fitting error and distension curve to arrive at an accurate measure of D<inf>d</inf>. To bring down the curve fitting time and facilitate processing on low-end processors, a novel approach using the autocorrelation of echoes from opposite walls of the artery has been discussed. The methods were analyzed for their comparative accuracy against reference D<inf>d</inf> obtained from 85 human volunteers using Hitachi-Aloka eTRACKING system. D<inf>d</inf> from all reported methods show strong and statistically significant positive correlation with eTRACKING and mean error of less than 7% could be achieved. As expected, D<inf>d</inf> from all methods show significant positive correlation with age.