Abstract
IntroductionRevascularization procedures in carotid artery stenosis have shown a positive effect in the restoration of cerebral oxygen metabolism as assessed by T2’ (T2 prime) imaging as well as capillary homeostasis by measurement of capillary transit time heterogeneity (CTH); however, data in patients with asymptomatic carotid stenosis without manifest brain lesions are scarce.Patients and MethodsThe effect of revascularization on the hemodynamic profile and capillary homeostasis was evaluated in 13 patients with asymptomatic high-grade carotid stenosis without ischemic brain lesions using dynamic susceptibility contrast perfusion imaging and oxygenation-sensitive T2’ mapping before and 6–8 weeks after revascularization by endarterectomy or stenting. The cognitive performance at both timepoints was further assessed.ResultsPerfusion impairment at baseline was accompanied by an increased CTH (p = 0.008) in areas with a time to peak delay ≥ 2 s in the affected hemisphere compared to contralateral regions. Carotid intervention improved the overall moderate hemodynamic impairment at baseline by leading to an increase in normalized cerebral blood flow (p = 0.017) and a decrease in mean transit time (p = 0.027), oxygen extraction capacity (OEC) (p = 0.033) and CTH (p = 0.048). The T2’ values remained unchanged.ConclusionThis study presents novel evidence of a state of altered microvascular function in patients with high-grade carotid artery stenosis in the absence of ischemic brain lesions, which shows sustained normalization after revascularization procedures.
Highlights
Revascularization procedures in carotid artery stenosis have shown a positive effect in the restoration of cerebral oxygen metabolism as assessed by T2’ (T2 prime) imaging as well as capillary homeostasis by measurement of capillary transit time heterogeneity (CTH); data in patients with asymptomatic carotid stenosis without manifest brain lesions are scarce
Data from a subset of these patients have recently been reported by Schröder et al, demonstrating a significant hypoperfusion that reversed after revascularization in the middle cerebral artery (MCA) territory of the affected side [21]
The CMRO2 is preserved in perfusion-restricted regions ipsilateral to stenosis owing to an increase in oxygen extraction capacity (OEC), which in turn is the result of reduced cerebral blood flow (CBF), elevated CTH, or both, in the affected carotid territories as compared to the contralateral side
Summary
Revascularization procedures in carotid artery stenosis have shown a positive effect in the restoration of cerebral oxygen metabolism as assessed by T2’ (T2 prime) imaging as well as capillary homeostasis by measurement of capillary transit time heterogeneity (CTH); data in patients with asymptomatic carotid stenosis without manifest brain lesions are scarce. Patients and Methods The effect of revascularization on the hemodynamic profile and capillary homeostasis was evaluated in 13 patients with asymptomatic high-grade carotid stenosis without ischemic brain lesions using dynamic susceptibility contrast perfusion imaging and oxygenation-sensitive T2’ mapping before and 6–8 weeks after revascularization by endarterectomy or stenting. Hemodynamic impairment and changes in oxygen metabolism play an important role in the risk of subsequent stroke in patients with symptomatic ICAS [4, 5], data from patients with asymptomatic disease are scarce and conflicting. The T2’ values normalized during the first days after carotid intervention, affirming the role of revascularization treatment in restoring cerebral oxygen metabolism [13]
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