Computational fluid dynamics modeling of symptomatic intracranial atherosclerosis may predict risk of stroke recurrence

Abstract

Background: Patients with symptomatic intracranial atherosclerosis (ICAS) of ≥ 70% luminal stenosis are at high risk of stroke recurrence. We aimed to evaluate the relationships between hemodynamics of ICAS revealed by computational fluid dynamics (CFD) models and risk of stroke recurrence in this patient subset.

Methods: Patients with a symptomatic ICAS lesion of 70-99% luminal stenosis were screened and enrolled in this study. CFD models were reconstructed based on baseline computed tomographic angiography (CTA) source images, to reveal hemodynamics of the qualifying symptomatic ICAS lesions. Change of pressures across a lesion was represented by the ratio of post- and pre-stenotic pressures. Change of shear strain rates (SSR) across a lesion was represented by the ratio of SSRs at the stenotic throat and proximal normal vessel segment, similar for the change of flow velocities. Patients were followed up for 1 year.

Results: Overall, 32 patients (median age 65; 59.4% males) were recruited. The median pressure, SSR and velocity ratios for the ICAS lesions were 0.40 (-2.46-0.79), 4.5 (2.2-20.6), and 7.4 (5.2-12.5), respectively. SSR ratio (hazard ratio [HR] 1.027; 95% confidence interval [CI], 1.004-1.051; P = 0.023) and velocity ratio (HR 1.029; 95% CI, 1.002-1.056; P = 0.035) were significantly related to recurrent territorial ischemic stroke within 1 year by univariate Cox regression, respectively with the c-statistics of 0.776 (95% CI, 0.594-0.903; P = 0.014) and 0.776 (95% CI, 0.594-0.903; P = 0.002) in receiver operating characteristic analysis.

Conclusions: Hemodynamics of ICAS on CFD models reconstructed from routinely obtained CTA images may predict subsequent stroke recurrence in patients with a symptomatic ICAS lesion of 70-99% luminal stenosis.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1. Evaluation of computational fluid dynamics model of an atherosclerotic lesion of left middle cerebral artery.

A: Post- and pre-stenotic pressures were measured using spherical volumes-of-interest (VOI, double arrows) at the first anatomically normal diameters distal (VOI 1) and proximal (VOI 2) to the lesion, respectively. The pressure ratio was calculated by dividing the mean pressure at VOI 1 by the mean pressure at VOI 2. B: Shear strain rates (SSR) were respectively measured at the stenotic throat (cut-plane 1) and at the first anatomically normal diameter (cut-plane 2) proximal to the lesion, by using cut-planes perpendicular to the direction of blood flow (arrow). The SSR ratio was calculated by dividing the SSR averaged over cut-plane 1 by the SSR averaged over cut-plane 2. C: Velocities were similarly measured (arrow) as with the SSRs, and the velocity ratio was similarly calculated as with the SSR ratio.

Figure 2. Kaplan-Meier curves for the cumulative probabilities of recurrent ischemic stroke in the territory (SIT) of the stenotic artery within 1 year after ictus, according to the shear strain rate (SSR) ratio (≥ or

Intracranial atherosclerotic lesions with a SSR ratio of ≥ median may relate to a higher risk of SIT, compared with lesions with a SSR ratio of

Figure 3. Kaplan-Meier curves for the cumulative probabilities of recurrent ischemic stroke in the territory (SIT) of the stenotic artery within 1 year after ictus, according to the velocity ratio (≥ or

Intracranial atherosclerotic lesions with a velocity ratio of ≥ median may relate to a higher risk of SIT, compared with lesions with a velocity ratio of

Figure 4. Receiver operating characteristic curves for shear strain rate ratio (left) and velocity ratio (right) to predict recurrent ischemic stroke in the territory of the qualifying artery.

SIT indicates recurrent ischemic stroke in the territory of the qualifying artery; AUC, area under curve.