A Prospective, Longitudinal Magnetic Resonance Imaging Evaluation of Cerebrovascular Reactivity and Infarct Development in Patients With Intracranial Stenosis

Abstract

Background Patients with symptomatic atherosclerotic and non‐atherosclerotic (i.e., moyamoya) intracranial steno‐occlusive disease experience high 2‐year infarct rates. Purpose To investigate whether cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) measures may provide biomarkers of 1‐to‐2‐year infarct risk. Study Type Prospective, longitudinal study. Subjects Adult participants (age = 18–85 years) with symptomatic intracranial atherosclerotic disease (N = 26) or non‐atherosclerotic (i.e., moyamoya; N = 43) and stenosis ≥50% of a major intracranial artery were initially scanned within 45 days of stroke. Follow‐up imaging (target = 1.5 years) was acquired for new infarct assessment. Field Strength/Sequence 3.0 Tesla with normocapnic arterial spin labeling (ASL) and blood oxygenation level‐dependent (BOLD) imaging acquired during an interleaved hypercapnic (3 minutes) and normocapnic (3 minutes) respiratory stimulus. Assessment CBF, maximum CVR, and time‐to‐maximum CVR (i.e., CVRDELAY) were calculated. Laterality indices (difference between infarcted and contralesional hemispheres divided by sum of absolute values) of metrics at enrollment were contrasted between participants with vs. without new infarcts on follow‐up. Statistical Tests Laterality indices were compared using non‐parametric Wilcoxon tests (significance: two‐sided P < 0.05) and effect sizes as Cohen's d. Continuous variables are presented as mean ± SD. Results New infarcts were observed on follow‐up in 15.0% of participants. The laterality index of the CVRDELAY was elevated (P = 0.01) in participants with atherosclerosis with new infarcts (index = 0.13) compared to participants without new infarcts (index = 0.05). Data Conclusion Elevated CVRDELAY may indicate brain parenchyma at increased risk for new infarcts in patients with symptomatic intracranial atherosclerotic disease treated with standard‐of‐care medical management. Level of Evidence 2 Technical Efficacy Stage 3

Choroid plexus vascular reactivity in moyamoya: Implications for choroid plexus regulation in ischemic stress

“…Figure 4 summarizes group results in participants who did not receive prior revascularization procedures, which reflect the primary study hypothesis. For the cortical region (Figure 4A), significant changes were observed on ANOVA across stenosis categories for CVR RAW ( p = .003), CVR MAX ( p = .01), and CVR DELAY ( p = .008), which is consistent with the fact that increasing levels of MCA or ICA steno‐occlusion reduce cerebrovascular reactivity and increase cerebrovascular delay times in the arterial territory of the affected vessel 20,21 . Figure 4A along with Table 2 shows that in nonsurgical participants, the cortical CVR RAW and CVR MAX decrease and CVR DELAY increases with increasing steno‐occlusion.…”

Presurgical Magnetic Resonance Imaging Indicators of Revascularization Response in Adults With Moyamoya Vasculopathy

“…2 Cerebrovascular reserve capacity and collateral circulation may be more specific indicators of vascular health and may portend collateral pathway formation in patients with moyamoya, and as such cerebrovascular reactivity (CVR) measures are being adopted with increasing frequency. 6,7 CVR may be evaluated by challenging vessels using a hypercapnic vasodilatory stimulus; in compliant vasculature, this leads to arteriolar smooth muscle relaxation and subsequential increase in cerebral blood volume (CBV) and CBF. The magnitude and timing of the CBV and CBF changes provide a marker of the hemodynamic reserve capacity or the potential ability of parenchyma to compensate for changes in perfusion pressure.…”

Arterial Transit Time‐Based Multidelay Combination Strategy Improves Arterial Spin Labeling Cerebral Blood Flow Measurement Accuracy in Severe Steno‐Occlusive Diseases

“…S troke is the second leading cause of mortality and disability worldwide. 1 In both acute [2][3][4] and chronic [5][6][7][8][9] cerebrovascular disorders, perfusion imaging helps in identifying the salvageable, hypoperfused tissue at risk for evaluating future strokes, as well as in selecting patients eligible for revascularization or reperfusion therapies. Traditionally, clinical perfusion imaging has entailed the use of exogenous contrast materials such as iodine or xenon for CT and gadolinium for MRI or radioactive tracers for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) 10 .…”