Differences in Wall Shear Stress Between High-Risk and Low-Risk Plaques in Patients With Moderate Carotid Artery Stenosis: A 4D Flow MRI Study

Abstract

This study aimed to evaluate the difference in wall shear stress (WSS) (axial, circumferential, and 3D) between high-risk and low-risk plaques in patients with moderate carotid artery stenosis and to identify which time points and directions play the dominant roles in determining the risk associated with plaques. Forty carotid arteries in 30 patients were examined in this study. All patients underwent high-resolution vessel wall (HRVW) imaging, diffusion-weighted imaging (DWI), and 4D flow MRI; HRVW imaging and DWI were used to separate low- and high-risk plaque. Twenty-four high-risk plaques and 16 low-risk plaques were enrolled. An independent-sample t-test was used to compare WSS between low- and high-risk plaques in the whole cardiac cycle and at 20 different time points in the cardiac cycle. The study found that patients with high-risk plaques had higher WSS than those with low-risk plaques throughout the entire cardiac cycle (p < 0.05), but the changes varied at the 20 different time points. The number of non-significant differences (p > 0.05) was less in diastole than in systole across different time points. The axial WSS values were higher than the circumferential WSS values; the difference in axial WSS values between high- and low-risk plaques was more significant than the difference in circumferential WSS, whereas 3D WSS values best reflected the difference between high-risk and low-risk plaques because they showed significant differences at every time point. In conclusion, increased WSS, especially during the diastolic period and in the axial direction, may be a signal of a high-risk plaque and may cause cerebrovascular events in patients with moderate carotid artery stenosis. Additionally, WSS can provide hemodynamic information and help clinicians make more appropriate decisions for patients with plaques.

WSSNet: Aortic Wall Shear Stress Estimation Using Deep Learning on 4D Flow MRI

“…It is noteworthy that WSSNet returns the WSS vectors at the vessel surface, which is useful for deriving other variables, such as TAWSS, OSI, and different WSS components (i.e., circumferential and longitudinal WSS). Previous studies explored the importance of this directional WSS ( 2 , 32 ) and WSS angle ( 33 ). Increased axial WSS can be an indicator of the presence of high-risk plaque ( 32 ) and another study suggested that axial WSS might explain different morphologies in ascending aorta dilatation ( 2 ).…”

“…Previous studies explored the importance of this directional WSS ( 2 , 32 ) and WSS angle ( 33 ). Increased axial WSS can be an indicator of the presence of high-risk plaque ( 32 ) and another study suggested that axial WSS might explain different morphologies in ascending aorta dilatation ( 2 ). WSS angle was suggested to be an independent predictor for proximal aortic dilatation for patients with bicuspid aortic valves ( 33 ).…”

Proximal Region of Carotid Atherosclerotic Plaque Shows More Intraplaque Hemorrhage: The Plaque at Risk Study

“…Wall shear stress is usually also higher in the upstream region with laminar flow, while the turbulent flow downstream of the maximal stenosis is associated with low shear stress levels. 11,12,14,33,[43][44][45][46][47] High wall shear stress promotes apoptosis of vascular smooth-muscle cells. 48 It also leads to an increased expression of endothelial adhesion molecules, resulting in an accumulation of macrophages, 32 which will result in an increased amount of metalloproteinases, which can break down the matrix of the overlying FC and, therefore, contribute to destabilization of the plaque.…”

“…Computational fluid dynamics and 4D flow MR imaging can be used to determine wall stress and wall shear stress. 46,47 Future studies are warranted that include computational fluid dynamics or 4D flow MR imaging to directly relate the local distribution of IPH and TRFC to wall stress and wall shear stress. If a causal relation is proved, it may lead to evaluation of new treatment options, such as pulse-pressure reduction.…”

Utility of vector flow mapping technology in quantitative assessment of carotid wall shear stress in hypertensive patients: A preliminary study

“…Intravascular ultrasound is regarded as an invasive operation, and images acquired by computed tomography angiography and MRI need to be reconstructed before post-analysis. Additionally, attempts have been made to incorporate four-dimensional blood-magnetic resonance imaging (4D Flow MRI) into the analysis of carotid blood flow dynamics ( 20 , 21 ). However, these results are often unsatisfactory due to the limited spatial resolution and time-consuming scanning procedure.…”