Arterial wall mechanical inhomogeneity detection and atherosclerotic plaque characterization using high frame rate pulse wave imaging in carotid artery disease patients in vivo

Abstract

Pulse Wave Imaging (PWI) is a non-invasive, ultrasound-based technique, which provides information on arterial wall stiffness by estimating the Pulse Wave Velocity (PWV) along an imaged arterial wall segment. The aims of the present study were to: 1) utilize the PWI information to automatically and optimally divide the artery into the segments with most homogeneous properties and 2) assess the feasibility of this method to provide arterial wall mechanical characterization in normal and atherosclerotic carotid arteries in vivo. A silicone phantom consisting of a soft and stiff segment along its longitudinal axis was scanned at the stiffness transition, and the PWV in each segment was estimated through static testing. The proposed algorithm detected the stiffness interface with an average error of 0.98±0.49 mm and 1.04±0.27 mm in the soft-to-stiff and stiff-to-soft pulse wave transmission direction, respectively. Mean PWVs estimated in the case of the soft-to-stiff pulse wave transmission direction were 2.47±0.04m/sec and 3.43±0.08 m/sec for soft and stiff phantom segments, respectively, while in the case of stiff-to-soft transmission direction PWVs were 2.60±0.18 m/sec and 3.72±0.08m/sec for the soft and stiff phantom segments, respectively, which were in good agreement with the PWVs obtained through static testing (soft segment: 2.41 m/sec, stiff segment: 3.52 m/sec). Furthermore, the carotid arteries of N=9 young subjects (22-32 y.o.) and N=9 elderly subjects (60-73 y.o.) with no prior history of carotid artery disease were scanned, in vivo, as well as the atherosclerotic carotid arteries of N=12 (59-85 y.o.) carotid artery disease patients. One-way ANOVA with Holm-Sidak correction showed that the number of most homogeneous segments in which the artery was divided was significantly higher in the case of carotid artery disease patients compared to young (3.25±0.86 segments vs 1.00±0.00 segments, p-value<0.0001) and elderly non-atherosclerotic subjects (3.25±0.86 segments vs 1.44±0.51 segments p-value<0.0001), indicating increased wall inhomogeneity in atherosclerotic arteries. The compliance provided by the proposed algorithm was significantly higher in non-calcified/high-lipid plaques as compared

Pulse wave and vector flow Imaging for atherosclerotic disease progression in hypercholesterolemic swine

“…Linear regression was performed to estimate the pulse wave velocity (PWV) corresponding to these different waves. To identify and quantify spatial variations in arterial wall properties across the imaged vessel adaptive PWI was utilized, which uses a graph-modelling framework in order to determine arterial segments where the pulse propagation is most homogeneous 31 . The number of detected segments are therefore related to how homogeneous the pulse propagation is, and expected to be correlated to vascular homogeneity.…”

“…This pulse wave velocity is related to the compliance of the vessel as described by the Bramwell-Hill equation 24 . This technique has previously been validated in simulations and phantoms 25 – 27 , as well as in-vivo for for mice 28 , 29 , swine 30 , and humans 31 . Recently, PWI has been incorporated with vector flow imaging, providing a comprehensive framework to assess vascular stiffness and hemodynamics together 32 – 34 .…”

Identification Markers of Carotid Vulnerable Plaques: An Update

“…IMT is widely used to assess carotid plaques with relatively low specificity [ 102 ]. PWV can suggest the stiffness of detected arterial wall segments via noninvasive pulse wave imaging [ 103 ]. Currently, GSM is most widely used to evaluate plaque vulnerability [ 100 ].…”

Evaluation of Plaque Characteristics and Inflammation Using Magnetic Resonance Imaging

“…In the clinic, however, the evaluation of the carotid-femoral PWV (cfPWV) and the brachial-ankle PWV (baPWV) are most common [ 94 ]. Ultrasound is, furthermore, used to characterize plaques in carotid artery disease patients in vivo [ 95 ] and to determine the local PWV in the human ascending aorta [ 96 ]. Also, for preclinical research of cardiovascular disease in animal models, new methods are constantly being developed.…”