Computational Fluid Dynamics Modeling of Symptomatic Intracranial Atherosclerosis May Predict Risk of Stroke Recurrence

Abstract

BackgroundPatients 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.MethodsPatients 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.ResultsOverall, 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.ConclusionsHemodynamics 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.

Fractional Flow Assessment for the Evaluation of Intracranial Atherosclerosis: A Feasibility Study

“…Currently, FF measurements can only be deduced from CFD studies or change of signal intensities on MRA. Leng et al [31] demonstrated on CFD models that the translesional pressure gradient has a trend towards being able to predict recurrent ischemic stroke risk in the territory of the treated artery within 1 year. Liebeskind et al [32] reported that the use of the signal intensity ratio index, calculated from the change of signal intensities based on flow-related contrast enhancement on time-of-flight MRA images, was associated with recurrent stroke in the territory of the stenotic artery, irrespective of the anatomical stenosis severity.…”

Evolution of intracranial atherosclerotic disease under modern medical therapy

“…3,49,50 Although we provided no concurrent histological evidence of resolving inflammation, the angiographic regression might signify diminished plaque vulnerability. Assuming other physical parameters are constant, based on Poiseuille's law and a computational fluid model we applied in ICAD, 51 a 16% reduction in maximal stenosis may result in a few-fold rise in the upstream-todownstream blood flow, and a 10 to 20% decrease in shear strain rate and pre-and poststenotic velocity ratio; these improvements in local hemodynamics might be associated with a diminished risk of cerebral ischemic events 51 and partly account for the decrease in the annual stroke risk of ICAD from the second year onward. 3,4 Notably, however, 14% of patients still failed this regimen and had recurrences in the immediate quarter from the qualifying stroke.…”

Hemodynamics and stroke risk in intracranial atherosclerotic disease

“…16,17 We have also indicated possible prognostic values of CFD model-generated hemodynamic metrics for the risk of recurrent stroke in a small cohort of 32 patients with 70 to 99% sICAS. 16,17 We have also indicated possible prognostic values of CFD model-generated hemodynamic metrics for the risk of recurrent stroke in a small cohort of 32 patients with 70 to 99% sICAS.…”