Geometry and Wall Shear Stress of the Contralesional Middle Cerebral Artery Are Associated With the Burden of Cerebral Small Vessel Disease in Acute Ischemic Stroke

Abstract

Background and purpose: Cerebral small vessel disease (cSVD) is associated with the vascular geometry of the intracranial arteries. This study aimed to determine the associations of the burden of pre-existing cSVD with the geometry and hemodynamic parameters of the middle cerebral artery (MCA) in patients with acute ischemic stroke.

Methods: This study enrolled consecutive patients with acute ischemic stroke in the MCA territory who underwent high-resolution vessel wall magnetic resonance imaging and four-dimensional flow magnetic resonance imaging in accordance with the protocol of Kyung Hee University Hospital. Patients were categorized into two groups based on the burden of pre-existing cSVD in the hemisphere contralateral to the stroke lesion: those with a modified burden score of 0-4 (low cSVD burden) and those with a modified burden score of 5-7 (high cSVD burden). The vascular geometry (straight, U-shaped, or inverted-U- and S-shaped) and wall shear stress (WSS) measured at five different points in the contralesional MCA were compared between the two burden groups.

Results: This study included 145 patients with cSVD: 109 with a low burden and 36 with a high burden. A low cSVD burden was correlated with a U- or inverted-U-shaped MCA (p< 0.001). A high cSVD burden was associated with an S-shaped MCA (reference U- or inverted U-shaped MCA: odds ratio [OR]=8.653, 95% confidence interval [CI]=2.789-26.843, p<0.001), and with an increased maximum WSS at the second quintile point (OR=1.109, 95% CI=1.005-1.225, p=0.040) and elevated variability (standard deviation: OR=1.759, 95% CI=1.277-2.423, p=0.001).

Conclusions: A tortuous MCA along with an increased WSS magnitude and variability were independently associated with a high cSVD burden.

Keywords: blood flow; cerebral small vessel disease; hemodynamics; magnetic resonance angiography; middle cerebral artery.

Fig. 1. Flowchart of the study. cSVD, cerebral small vessel disease; HRVWI, high-resolution vessel wall magnetic resonance imaging; MCA, middle cerebral artery; MRI, magnetic resonance imaging.

Fig. 2. Representative cases of the maximum WSS in patients with high and low cSVD burdens. A and B: Acute cerebral infarction (yellow arrow) in the left hemisphere with a high cSVD burden in the contralesional hemisphere. C: Contralesional S-shaped MCA (dotted line) with severe degree of stenosis in the left MCA M1 segment. D: Elevated magnitudes and variability of the maximum WSS (yellow line) were observed. E and F: An acute cerebral infarction (yellow arrow) in the left hemisphere with a low cSVD burden in the contralesional hemisphere. G: Contralesional U- or inverted-U-shaped MCA (dotted line) with severe degree of stenosis in the left MCA M1 segment. H: Decreased magnitudes and variability of the maximum WSS (blue line) were observed. cSVD, cerebral small vessel disease; MCA, middle cerebral artery; WSS, wall shear stress.