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

Exploration of the risk factor for infarction after revascularization in moyamoya disease

RESULTS

Eventually, 108 consecutive patients received 174 surgeries were enrolled, experienced new or expanded infarction occured in 13 (7.47%) surgeries, which showed higher Suzuki stage on the non-operative side, more posterior cerebral artery (PCA) involvement, and more intraoperative hypotension compared to those without infarction(p < .05). The Suzuki stage on the non-operative side had the highest area under the curve (AUC) of 0.737, with a sensitivity of 0.692 and specificity of 0.783. Combination of the three factors showed better efficiency, with an AUC of 0.762, a sensitivity of 0.692, and a specificity of 0.907.

CONCLUSIONS

Revascularization was a safe option for patients with MMD, higher Suzuki stage on the non-operative side, PCA involvement, and intraoperative hypotension might be the risk factors for new or expanded infarction after revascularization in patients with MMD.

High-resolution magnetic resonance vessel wall imaging provides new insights into Moyamoya disease

Moyamoya disease (MMD) is a rare condition that affects the blood vessels of the central nervous system. This cerebrovascular disease is characterized by progressive narrowing and blockage of the internal carotid, middle cerebral, and anterior cerebral arteries, which results in the formation of a compensatory fragile vascular network. Currently, digital subtraction angiography (DSA) is considered the gold standard in diagnosing MMD. However, this diagnostic technique is invasive and may not be suitable for all patients. Hence, non-invasive imaging methods such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are often used. However, these methods may have less reliable diagnostic results. Therefore, High-Resolution Magnetic Resonance Vessel Wall Imaging (HR-VWI) has emerged as the most accurate method for observing and analyzing arterial wall structure. It enhances the resolution of arterial walls and enables quantitative and qualitative analysis of plaque, facilitating the identification of atherosclerotic lesions, vascular entrapment, myofibrillar dysplasia, moyamoya vasculopathy, and other related conditions. Consequently, HR-VWI provides a new and more reliable evaluation criterion for diagnosing vascular lesions in patients with Moyamoya disease.

Cerebrovascular reactivity dispersion as a new biomarker of recent stroke symptomatology in moyamoya

Background

Moyamoya disease (MMD) is a non-atherosclerotic intracranial steno-occlusive condition placing patients at high risk for ischemic stroke. Direct and indirect surgical revascularization can improve blood flow in MMD; however, randomized trials demonstrating efficacy have not been performed and biomarkers of parenchymal hemodynamic impairment are needed to triage patients for interventions and evaluate post-surgical efficacy. We test the hypothesis that hypercapnia-induced maximum cerebrovascular reactivity (CVR MAX ) and the more novel indicator cerebrovascular reactivity (CVR) response time (CVR DELAY ), both assessed from time-regression analyses of non-invasive hypercapnic imaging, correlate with recent focal ischemic symptoms.

Methods

Hypercapnic reactivity medical resonance imaging (blood oxygenation level-dependent; echo time=35ms; spatial resolution=3.5×3.5×3.5mm) and catheter angiography assessments of cortical reserve capacity and vascular patency, respectively, in MMD participants (n=73) were performed in sequence. Time regression analyses were applied to quantify CVR MAX and CVR DELAY . Symptomatology information for each hemisphere (n=109) was categorized into symptomatic (ischemic symptoms within six months) or asymptomatic (no history of ischemic symptoms) and logistic regression analysis assessed the association of CVR metrics with ischemic symptoms after controlling for age and sex.

Results

Symptomatic hemispheres displayed lengthened CVR DELAY (p<0.001), which was more discriminatory between hemispheres than CVR MAX (p=0.037). CVR DELAY (p<0.001), but not CVR MAX (p=0.127), was found to be sensitively related to age in asymptomatic tissue (0.33-unit increase/year); age-dependent normative ranges are presented to enable quantitative assessment of patient-specific impairment. Furthermore, the area under the receiver operating characteristic curves shows that CVR DELAY predicts ischemic symptoms (p<0.001), whereas CVR MAX does not (p=0.056).

Conclusion

Findings support that CVR metrics are uniquely altered in hemispheres with recent ischemic symptoms, motivating the investigation of CVR as a surrogate of ischemic symptomatology and treatment efficacy.

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

BACKGROUND AND PURPOSE

Choroid plexus (ChP) hyperemia has been observed in patients with intracranial vasculopathy and to reduce following successful surgical revascularization. This observation may be attributable to impaired vascular reserve of the ChP or other factors, such as the ChP responding to circulating markers of stress. We extend this work to test the hypothesis that vascular reserve of the ChP is unrelated to intracranial vasculopathy.

METHODS

We performed hypercapnic reactivity (blood oxygenation level-dependent; echo time = 35 ms; spatial resolution = 3.5 × 3.5 × 3.5 mm, repetition time = 2000 ms) and catheter angiography assessments of ChP reserve capacity and vascular patency in moyamoya patients (n = 53) with and without prior surgical revascularization. Time regression analyses quantified maximum cerebrovascular reactivity and reactivity delay time in ChP and cortical flow territories of major intracranial vessels with steno-occlusion graded as <70%, 70%-99%, and occlusion using Warfarin-Aspirin-Symptomatic-Intracranial-Disease stenosis grading criteria. Analysis of variance (significance: two-sided Bonferroni-corrected p < .05) was applied to evaluate cortical and ChP reactivity, after accounting for end-tidal carbon dioxide change, for differing vasculopathy categories.

RESULTS

In patients without prior revascularization, arterial vasculopathy was associated with reduced cortical reactivity and lengthened reactivity delay (p ≤ .01), as expected. Regardless of surgical history, the ChP reactivity metrics were not significantly related to the degree of proximal stenosis, consistent with ChP reactivity being largely preserved in this population.

CONCLUSIONS

Findings are consistent with ChP reactivity in moyamoya not being dependent on observed vasculopathy. Future work may investigate the extent to which ChP hyperemia in chronic ischemia reflects circulating markers of glial or ischemic stress.

Editorial for "Pre-Surgical Magnetic Resonance Imaging Indicators of Revascularization Response in Adults With Moyamoya Vasculopathy"

Background:

Moyamoya is a progressive intracranial vasculopathy, primarily affecting distal segments of the internal carotid and middle cerebral arteries. Treatment may comprise angiogenesis-inducing surgical revascularization, however lack of randomized trials often results in subjective treatment decisions.

Hypothesis:

Compensatory pre-surgical posterior vertebrobasilar (VBA) flow-territory reactivity, including greater cerebrovascular reactivity and reduced vascular delay time, portends greater neoangiogenic response verified on digital subtraction angiography (DSA) at one-year follow-up.

Study Type:

Prospective intervention cohort.

Subjects:

31 patients with moyamoya (26 female; age=45±13 years; 41 revascularized hemispheres).

Methods:

Anatomical MRI, hypercapnic cerebrovascular reactivity MRI, and DSA acquired pre-surgically in adult moyamoya participants scheduled for clinically-indicated surgical revascularization. One year post-surgery, DSA was repeated to evaluate collateralization.

Field Strength:

3 Tesla.

Sequence:

Hypercapnic T 2*-weighted gradient-echo blood-oxygenation-level-dependent, T 2-weighted turbo-spin-echo fluid-attenuated-inversion-recovery, T 1-weighted magnetization-prepared-rapid-gradient-echo, and T 2-weighted diffusion-weighted imaging.

Assessment:

Pre-surgical maximum cerebrovascular reactivity and response times were evaluated in VBA flow-territories. Revascularization success was determined using an ordinal scoring system of neoangiogenic collateralization from post-surgical DSA by two cerebrovascular neurosurgeons (RVC; experience=8 years; MRF, experience=9 years) and one neuroradiologist (LTD, experience=8 years). Stroke risk factors (age, sex, race, vasculopathy, and diabetes) were recorded.

Statistical Tests:

Fisher’s exact and Wilcoxon rank-sum tests were applied to compare pre-surgical variables between cohorts with angiographically-confirmed good (>1/3 MCA territory revascularized) vs. poor (<1/3 MCA territory revascularized) outcomes. Significance: two-sided p<0.05. Normalized odds ratios (OR) were calculated.

Results:

Criteria for good collateralization were met in 25 of 41 revascularized hemispheres. Pre-surgical normalized VBA flow-territory cerebrovascular reactivity was significantly higher in those with good (1.12±0.13 unitless) vs. poor (1.04±0.05 unitless) outcomes. Younger (OR=−0.60±0.67) and White (OR=−1.81±1.40) participants had highest revascularization success (good outcomes: age=42±14 years, race=84% White; poor outcomes: age=49±11 years, race=44% White).

Data Conclusion:

Pre-surgical MRI-measures of VBA flow-territory cerebrovascular reactivity are highest in moyamoya participants with better angiographic responses to surgical revascularization.