Analysis of sequential ultrasound frames for the measurement of hemodynamic stresses, critical bent buckling pressure, and critical buckling torque of human common carotid atherosclerosis

BACKGROUND

Structural properties of the arterial wall are important diagnostic parameters. The current study aimed at investigating the hemodynamic properties and intima-media thickness changes of the common carotid artery in human subjects with atherosclerosis in order to determine the relationships between these indices.

METHODS

This study presented methods to detect instantaneous changes in the lumen diameter, intima media thickness, longitudinal movement and acceleration, and velocity of the left side of common carotid artery. These parameters were measured in 155 male patients, categorized into control (n = 42), mild (n = 39), moderate (n = 37), and severe (n = 37) carotid stenosis groups by B-mode and Doppler ultrasonography. Extracted parameters were used to estimate the biomechanical properties of arteries, including radial strain, arterial stiffness index, Young's elastic modulus, circumferential stress, shear stress, axial stress, critical bent buckling pressure, and critical buckling torque.

FINDINGS

All biomechanical parameters of common carotid artery were significantly different in patients with mild, moderate, and severe stenosis, compared to the control group (P < 0.05). Moreover, the current results showed a significant correlation between intima media thickness and non-intima media thickness-based biomechanical indices including circumferential strain, stiffness index, and shear stress in different stenosis groups (P < 0.05).

INTERPRETATION

We concluded that the conventional and new indicators such as axial stress, critical bent buckling pressure, critical buckling torque could be useful for evaluating atherosclerosis development and also, may provide more information for physicians and interventional radiologists in designing strategies for decreasing risk in interventional treatment such as stent replacement and differentiation of vulnerable plaques.

Vascular deformation in human atherosclerotic carotid artery evaluated by 2D analysis of ultrasonography

OBJECTIVES

Common carotid artery (CCA) remodelling in the atherosclerosis process is an inherent necessary element that decreases the progress of significant lumen compromise. The present study used a semi-automated method to assess relationships of intima-media thickness (IMT), lumen diameter (LD) and inter-adventitial diameter (IAD) using ultrasound B-mode images of atherosclerotic carotid artery.

METHODS

In the cross-sectional study, 120 male subjects (age range: 40-60 years) were classified into four research groups namely control, mild, moderate, and severe stenosis. The maximum near and far wall IMT, mean of both walls' IMT and IAD, and also LD of the left CCA were extracted for all participants. Pearson correlation coefficient was utilized to investigate relationships of IMT, LD, and IAD.

RESULTS

Results revealed that the maximum far and near wall IMT, mean of both walls' IMT and IAD in the CCA were significantly different in stenosis patients and the control group (p< 0.001). However, there were no significant differences among the four studied groups in terms of LD of CCA (p = 0.65). There was a stronger correlation between mean of both walls' IMT and IAD in comparison with mean far wall IMT and IAD (p < 0.001).

CONCLUSIONS

Results indicated that changes of IAD in the left CCA were associated with carotid deformation, and thus it can be considered as a predictor of atherosclerosis process.

A New 2D-Based Method for Carotid Intima-Media Thickness Quantification From Ultrasound Sequences

Background:

Ultrasound measurement of carotid Intima-Media Thickness (IMT) is a suitable method to evaluate subclinical arteriosclerosis.

Objectives:

The current study aimed to present a new computerized algorithm to detect instantaneous changes of the IMT to Common Carotid Artery (CCA) of IMT in sequential ultrasound images by applying the maximum gradient and the dynamic programming.

Patients and Methods:

In a cross-sectional design, an examination was performed on thirty healthy human subjects with the mean age of 44 ± 6 years from April 2013 to June 2013 in Beheshti Hospital, Kashan, Iran. In all individuals, the instantaneous changes of the far wall IMT on the CCA were extracted. Local measurements of vessel intensity, intensity gradient, and boundary continuity were extracted for all of the sequential ultrasonic 2D-frames throughout three cardiac cycles. The Pearson correlation coefficients and Bland-Altman analysis were performed to assess the relationship and agreement between IMT measured by the proposed and conventional manual methods.

Results:

There was no significant difference between the proposed and manual methods with paired t-test analysis (in systole: 0.57 ± 0.10 vs. 0.56 ± 0.10 mm; P = 0.188 and in diastole: 0.63 ± 0.16 vs. 0.62 ± 0.10 mm; P = 0.122 for the manual and proposed methods, respectively). The Pearson correlation coefficients were r = 0.94 and r = 0.93 for IMT_s and IMT_d, respectively (both P < 0.001). Limit of agreements were narrow and considerable agreement was found between the two methods.

Conclusions:

The present study demonstrated that the proposed computerized analyzing method can provide accurate measurements of the IMT of the CCA in sequential 2D ultrasonic images.