Abstract
An internal carotid artery (ICA) stenosis can potentially decrease the perfusion pressure to the brain. In this study, computational fluid dynamics (CFD) was used to study if there was a hemispheric pressure laterality between the contra- and ipsilateral middle cerebral artery (MCA) in patients with a symptomatic ICA stenosis. We further investigated if this MCA pressure laterality (ΔPMCA) was related to the hemispheric flow laterality (ΔQ) in the anterior circulation, i.e., ICA, proximal MCA and the proximal anterior cerebral artery (ACA). Twenty-eight patients (73±6 years, range 59–80 years, 21 men) with symptomatic ICA stenosis were included. Flow rates were measured using 4D flow MRI data (PC-VIPR) and vessel geometries were obtained from computed tomography angiography. The ΔPMCA was calculated from CFD, where patient-specific flow rates were applied at all input- and output boundaries. The ΔPMCA between the contra- and ipsilateral side was 6.4±8.3 mmHg (p<0.001) (median 3.9 mmHg, range -1.3 to 31.9 mmHg). There was a linear correlation between the ΔPMCA and ΔQICA (r = 0.85, p<0.001) and ΔQACA (r = 0.71, p<0.001), respectively. The correlation to ΔQMCA was weaker (r = 0.47, p = 0.011). In conclusion, the MCA pressure laterality obtained with CFD, is a promising physiological biomarker that can grade the hemodynamic disturbance in patients with a symptomatic ICA stenosis.
Highlights
An internal carotid artery (ICA) stenosis is a major risk factor for a transient ischemic attack (TIA) or a stroke
Degree of ipsilateral ICA stenosis was not correlated to ΔPMCA (r = 0.23, p = 0.23)
The ΔPMCA was estimated in patients with a symptomatic ICA stenosis by computational fluid dynamics (CFD) analysis, using computed tomography angiography (CTA) vessel geometries of the anterior circle of Willis (CW), together with blood flow rates from 4D flow MRI
Summary
An internal carotid artery (ICA) stenosis is a major risk factor for a transient ischemic attack (TIA) or a stroke. In addition to the embolization risk [1, 2], a severe stenosis (70–99%) may cause abnormal pressure and flow asymmetries in the cerebral arterial tree [3]. The cerebral autoregulation of the cerebrovascular resistance further works to maintain a constant total cerebral blood flow for varying cerebral perfusion pressures, as described by Lassen’s autoregulatory curve [6]. A hemispheric MCA pressure laterality may be viewed as a measure of the separation between the two MCAs on the Lassen curve (Fig 1).
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