P6.01 ULTRASOUND EVALUATION OF LOCAL ARTERIAL STIFFNESS: FEASIBILITY STUDY IN AN ANIMAL MODEL OF ADVANCED ATHEROSCLEROSIS

Abstract

Atherosclerosis is a pathological process affecting arterial elasticity. The rabbit is one of the most widely used animal models for atherosclerosis research. The aim of this study was to evaluate the feasibility of a method for the automatic assessment of local vascular stiffness in rabbits. An off-line algorithm for the evaluation of arterial diameter (D) and distension (ΔD) from ultrasound image sequences was developed in Matlab and tested in 3 atherosclerotic and 2 control rabbits. Longitudinal scans of the aortic and carotid arteries of the rabbits were recorded in DICOM format. High frame-rate (330Hz) image sequences (3 seconds) were acquired to track the rapid movement of the vessel (heart rate ∼ 240bpm) using iE33 Philips ultrasound system. The probe was hold by a clamp. The measurement variability was assessed by performing two scans for each subject. The high frame-rate provided a temporal resolution of 3 msec allowing the instantaneous tracking of the diameter curve for both carotid and aorta. As regards the variability, the coefficients of variation were: 3%±2% (D) and 7%±3% (ΔD) for the aorta (mean D=3.2mm) and 3%±2% (D) and 5%±4% (ΔD) for the carotid (mean D=1.99mm). Our data demonstrate that the implemented ultrasound image processing algorithm is able to non-invasively assess the vascular instantaneous diameter both in control and atherosclerotic rabbits. The method, together with intra-central ear artery blood pressure measurement, could evaluate the effects of new therapeutic interventions on vascular stiffness in those pathological conditions characterized by arterial dysfunction, such as atherosclerosis.