Strain assessment in the carotid artery wall using ultrasound speckle tracking: validation in a sheep model

Abstract

The aim of this study was to validate carotid artery strain assessment in-vivo using ultrasound speckle tracking. The left carotid artery of five sheep was exposed and sonomicrometry crystals were sutured onto the artery wall to obtain reference strain. Ultrasound imaging was performed at baseline and stress, followed by strain estimation using an in-house speckle tracking algorithm tuned for vascular applications. The correlation between estimated and reference strain was r = 0.95 (p < 0.001) and r = 0.87 (p < 0.01) for longitudinal and circumferential strain, respectively. Moreover, acceptable limits of agreement were found in Bland-Altman analysis (longitudinally: -0.15 to 0.42%, circumferentially: -0.54 to 0.50%), which demonstrates the feasibility of estimating carotid artery strain using ultrasound speckle tracking. However, further studies are needed to test the algorithm on human in-vivo data and to investigate its potential to detect subclinical cardiovascular disease and characterize atherosclerotic plaques.

Noninvasive Vascular Elastography With Plane Strain Incompressibility Assumption Using Ultrafast Coherent Compound Plane Wave Imaging

“…Vascular strain analysis has recently gained a lot of interest [48][49][50][51][52][53][54] as elevated shear movements might be associated with plaque development leading to its rupture. For examples, recent in vivo studies using endovascular elastography (EVE) on a diabetic pig model [51] and on humans, prior and following coronary atherectomy interventions [52] revealed the potential of radial shear strains to detect and classify atherosclerotic plaques according to American Heart Association classes [55].…”

Speckle tracking carotid artery circumferential strain is a marker of arterial sclerosis but not coronary atherosis

“…Carotid artery circumferential strain measurements were carried out using software designed to assess myocardial strain. This may not be ideal as the carotid wall is much thinner than the myocardium and specialized software, such as that used in recent work validating speckle tracking CS with sonomicrometry, may be more effective . Owing to ultrasound dropout in the side walls of the artery, only far wall strain was reliably assessable; similar findings were reported by Yang and colleagues .…”

“…ST carotid circumferential strain (CS) has been found to correlate with conventional ultrasound measurements of carotid stiffness . It has also demonstrated good inter‐observer and intra‐observer variability and its validity as a measure of stiffness has been confirmed using sonomicrometry in sheep carotid arteries . Posterior, or far wall, circumferential strain (FWCS) appears to be the most reliable …”

A new inverse method for estimation of in vivo mechanical properties of the aortic wall

“…Automatic algorithms [45–50] for 3D+t LV segmentation and tracking using ultrasound images have been developed over the last eight years. As for ultrasound speckle tracking of vessel wall, Larsson, et al [51] performed validation experiments, in which crystal markers were implanted on the artery wall in order to obtain the “ground truth” strain measurement. 3D+t ultrasound speckle tracking has been applied to study aortic wall strain of healthy and abdominal aortic aneurysms patients in vivo by Karatolios, et al [52].…”