Most Promising Approaches to Improve Brain AVM Management: ARISE I Consensus Recommendations.

Brain arteriovenous malformations (bAVMs) are complex, and rare arteriovenous shunts that present with a wide range of signs and symptoms, with intracerebral hemorrhage being the most severe. Despite prior societal position statements, there is no consensus on the management of these lesions. ARISE (Aneurysm/bAVM/cSDH Roundtable Discussion With Industry and Stroke Experts) was convened to discuss evidence-based approaches and enhance our understanding of these complex lesions. ARISE identified the need to develop scales to predict the risk of rupture of bAVMs, and the use of common data elements to perform prospective registries and clinical studies. Additionally, the group underscored the need for comprehensive patient management with specialized centers with expertise in cranial and spinal microsurgery, neurological endovascular surgery, and stereotactic radiosurgery. The collection of prospective multicenter data and gross specimens was deemed essential for improving bAVM characterization, genetic evaluation, and phenotyping. Finally, bAVMs should be managed within a multidisciplinary framework, with clinical studies and research conducted collaboratively across multiple centers, harnessing the collective expertise and centralization of resources.

Racial and Ethnic Disparities in the Medical Management of Poststroke Complications Among Patients With Acute Stroke.

BACKGROUND: To inform clinical practice, we sought to identify racial and ethnic differences in the medical management of common poststroke complications. METHODS AND RESULTS: A cohort of acutely hospitalized, first-time non-Hispanic White (NHW), non-Hispanic Black, and Hispanic patients with stroke was identified from electronic medical records of 51 large health care organizations (January 1, 2003 to December 5, 2022). Matched propensity scores were used to account for baseline differences. Primary outcomes included receipt of medication(s) associated with the management of the following poststroke complications: arousal/fatigue, spasticity, mood, sleep, neurogenic bladder, neurogenic bowel, and seizure. Differences were measured at 14, 90, and 365 days. Subgroup analyses included differences restricted to patients with ischemic stroke, younger age (<65 years), and stratified by decade (2003-2012 and 2013-2022). Before matching, the final cohort consisted of 348 286 patients with first-time stroke. Matching resulted in 63 722 non-Hispanic Black-NHW pairs and 24 009 Hispanic-NHW pairs. Non-Hispanic Black (versus NHW) patients were significantly less likely to be treated for all poststroke complications, with differences largest for arousal/fatigue (relative risk (RR), 0.58 [95% CI, 0.54-0.62]), spasticity (RR, 0.64 [95% CI, 0.0.62-0.67]), and mood disorders (RR, 0.72 [95% CI, 0.70-0.74]) at 14 days. Hispanic-NHW differences were similar, albeit with smaller magnitudes, with the largest differences present for spasticity (RR, 0.67 [95% CI, 0.63-0.72]), arousal/fatigue (RR, 0.77 [95% CI, 0.70-0.85]), and mood disorders (RR, 0.79 [95% CI, 0.77-0.82]). Subgroup analyses revealed similar patterns for ischemic stroke and patients aged <65 years. Disparities for the current decade remained significant but with smaller magnitudes compared with the prior decade. CONCLUSIONS: There are significant racial and ethnic disparities in the treatment of poststroke complications. The differences were greatest at 14 days, outlining the importance of early identification and management.

Polyetheretherketone Implant Cranioplasty for Large Cranial Defects: A Seven-Year Follow-Up.

BACKGROUND: Goals of a cranioplasty include protection of the brain, restoration of normal appearance, and neurological function improvement. Although choice of materials for cranial remodeling has changed through the years, computer-designed polyetheretherketone (PEEK) implant has gained traction as a preferred material used for cranioplasty. However, long-term outcomes and complications of PEEK implants remain limited. The goal of this study was to report long-term clinical outcomes after PEEK implant cranioplasty. METHODS: A retrospective chart review was performed on patients undergoing PEEK cranioplasty between January 2007 and February 2023. Preoperative, intraoperative, and postoperative data were collected and analyzed. RESULTS: Twenty-two patients were included in this study. Mean postoperative follow-up time was 83.45 months (range: 35.47-173.87). Before PEEK implant cranioplasty, patients with multiple cranial procedures had undergone a mean of 2.95 procedures. PEEK implant cranioplasty indications were prior implant infection (14) and secondary reconstruction of cranial defect (8). The mean implant size was 180.43 cm2 (range: 68.00-333.06). Four patients received a 2-piece implant. Postoperative complications included: perioperative subgaleal self-resolving fluid collection in 1 patient, hematoma in another, and 3 infections resulting in explantations with successful reinsertion in 2 patients. Four of 5 patients with preoperative history of seizures reported improved seizures and all 4 patients with preoperative syndrome of the trephined reported improved symptoms and neurological function. CONCLUSION: At a mean follow-up of 7 years, most PEEK implants continued to provide protection to the brain and consistent symptom relief in patients suffering from prior postcraniectomy/craniotomy sequelae of seizures and syndrome of the trephined.

A Transcriptomic Comparative Study of Cranial Vasculature.

In genetic studies of cerebrovascular diseases, the optimal vessels to use as controls remain unclear. Our goal is to compare the transcriptomic profiles among 3 different types of control vessels: superficial temporal artery (STA), middle cerebral arteries (MCA), and arteries from the circle of Willis obtained from autopsies (AU). We examined the transcriptomic profiles of STA, MCA, and AU using RNAseq. We also investigated the effects of using these control groups on the results of the comparisons between aneurysms and the control arteries. Our study showed that when comparing pathological cerebral arteries to control groups, all control groups presented similar responses in the activation of immunological processes, the regulation of intracellular signaling pathways, and extracellular matrix productions, despite their intrinsic biological differences. When compared to STA, AU exhibited upregulation of stress and apoptosis genes, whereas MCA showed upregulation of genes associated with tRNA/rRNA processing. Moreover, our results suggest that the matched case-control study design, which involves control STA samples collected from the same subjects of matched aneurysm samples in our study, can improve the identification of non-inherited disease-associated genes. Given the challenges associated with obtaining fresh intracranial arteries from healthy individuals, our study suggests that using MCA, AU, or paired STA samples as controls are feasible strategies for future large-scale studies investigating cerebral vasculopathies. However, the intrinsic differences of each type of control should be taken into consideration when interpreting the results. With the limitations of each control type, it may be most optimal to use multiple tissues as controls.

Deep-learning-enabled brain hemodynamic mapping using resting-state fMRI.

Cerebrovascular disease is a leading cause of death globally. Prevention and early intervention are known to be the most effective forms of its management. Non-invasive imaging methods hold great promises for early stratification, but at present lack the sensitivity for personalized prognosis. Resting-state functional magnetic resonance imaging (rs-fMRI), a powerful tool previously used for mapping neural activity, is available in most hospitals. Here we show that rs-fMRI can be used to map cerebral hemodynamic function and delineate impairment. By exploiting time variations in breathing pattern during rs-fMRI, deep learning enables reproducible mapping of cerebrovascular reactivity (CVR) and bolus arrival time (BAT) of the human brain using resting-state CO2 fluctuations as a natural "contrast media". The deep-learning network is trained with CVR and BAT maps obtained with a reference method of CO2-inhalation MRI, which includes data from young and older healthy subjects and patients with Moyamoya disease and brain tumors. We demonstrate the performance of deep-learning cerebrovascular mapping in the detection of vascular abnormalities, evaluation of revascularization effects, and vascular alterations in normal aging. In addition, cerebrovascular maps obtained with the proposed method exhibit excellent reproducibility in both healthy volunteers and stroke patients. Deep-learning resting-state vascular imaging has the potential to become a useful tool in clinical cerebrovascular imaging.

2023 Guideline for the Management of Patients With Aneurysmal Subarachnoid Hemorrhage: A Guideline From the American Heart Association/American Stroke Association.

AIM: The "2023 Guideline for the Management of Patients With Aneurysmal Subarachnoid Hemorrhage" replaces the 2012 "Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage." The 2023 guideline is intended to provide patient-centric recommendations for clinicians to prevent, diagnose, and manage patients with aneurysmal subarachnoid hemorrhage. METHODS: A comprehensive search for literature published since the 2012 guideline, derived from research principally involving human subjects, published in English, and indexed in MEDLINE, PubMed, Cochrane Library, and other selected databases relevant to this guideline, was conducted between March 2022 and June 2022. In addition, the guideline writing group reviewed documents on related subject matter previously published by the American Heart Association. Newer studies published between July 2022 and November 2022 that affected recommendation content, Class of Recommendation, or Level of Evidence were included if appropriate. Structure: Aneurysmal subarachnoid hemorrhage is a significant global public health threat and a severely morbid and often deadly condition. The 2023 aneurysmal subarachnoid hemorrhage guideline provides recommendations based on current evidence for the treatment of these patients. The recommendations present an evidence-based approach to preventing, diagnosing, and managing patients with aneurysmal subarachnoid hemorrhage, with the intent to improve quality of care and align with patients' and their families' and caregivers' interests. Many recommendations from the previous aneurysmal subarachnoid hemorrhage guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

Variability in the Transition of Care to Poststroke Rehabilitation During the First Wave of COVID-19.

OBJECTIVE: The aim of the study is to evaluate transitions of acute stroke and inpatient rehabilitation facility care during the first wave of COVID-19. DESIGN: This is a retrospective observational study (3 comprehensive stroke centers with hospital-based inpatient rehabilitation facilities) between January 1, 2019, and May 31, 2019 (acute stroke = 584, inpatient rehabilitation facility = 210) and January 1, 2020, and May 31, 2020 (acute stroke = 534, inpatient rehabilitation facility = 186). Acute stroke characteristics included stroke type, demographics, and medical comorbidities. The proportion of patients admitted for acute stroke and inpatient rehabilitation facility care was analyzed graphically and using t test assuming unequal variances. RESULTS: The proportion of intracerebral hemorrhage patients (28.5% vs. 20.5%, P = 0.035) and those with history of transient ischemic attack (29% vs. 23.9%; P = 0.049) increased during the COVID-19 first wave in 2020. Uninsured acute stroke admissions decreased (7.3% vs. 16.6%) while commercially insured increased (42.7% vs. 33.4%, P < 0.001).Acute stroke admissions decreased from 116.5 per month in 2019 to 98.8 per month in 2020 ( P = 0.008) with no significant difference in inpatient rehabilitation facility admissions (39 per month in 2019, 34.5 per month in 2020; P = 0.66).In 2019, monthly changes in acute stroke admissions coincided with inpatient rehabilitation facility admissions.In 2020, acute stroke admissions decreased 80.6% from January to February, while inpatient rehabilitation facility admissions remained stable. Acute stroke admissions increased 12.8% in March 2020 and remained stable in April, while inpatient rehabilitation facility admissions decreased by 92%. CONCLUSIONS: Acute stroke hospitalizations significantly decreased per month during the first wave of COVID-19, with a delayed effect on the transition from acute stroke to inpatient rehabilitation facility care.

Effect of inpatient rehabilitation facility care on ninety day modified Rankin score in ischemic stroke patients.

OBJECTIVE: To determine Inpatient Rehabilitation Facility (IRF) treatment effect on modified Rankin Scale (mRS) scores at 90 days in acute ischemic stroke (AIS) patients. MATERIALS AND METHODS: This prospective cross-sectional study included 738 AIS patients admitted 1/1/2018-12/31/2020 to a Comprehensive Stroke Center with a Stroke Rehabilitation program. We compared outcomes for patients who went directly home versus went to IRF at hospital discharge: (1) acute care length of stay (LOS), (2) National Institutes of Health Stroke Scale (NIHSS) score, (3) mRS score at hospital discharge and 90 days, (4) the proportion of mRS scores ≤ 2 from hospital discharge to 90 days. RESULTS: Among 738 patients, 499 went home, and 239 went to IRF. IRF patients were more likely to have increased acute LOS (10.7 vs 3.9 days; t-test, P<0.0001), increased mean NIHSS score (7.8 vs 4.8; t-test, P<0.0001) and higher median mRS score (3 vs 1, t-test, P<0.0001) compared to patients who went home. At 90 days, ischemic stroke patients who received IRF care were more likely to progress to a mRS ≤ 2 (18.7% increase) compared to patients discharged home from acute care (16.3% decrease). Home patients experienced a one-point decrease in mRS at 90 days compared to those who received IRF treatment (median mRS of 3 vs. 2, t-test, P<0.05). CONCLUSIONS: In ischemic stroke patients, IRF treatment increased the likelihood of achieving mRS ≤ 2 at 90 days indicating the ability to live independently, and decreased the likelihood of mRS decrease, compared with patients discharged directly home after acute stroke care.

The effects of aneurysmal subarachnoid hemorrhage on cerebral vessel diameter and flow velocity.

BACKGROUND: Transcranial Doppler flow velocity is used to monitor for cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Generally, blood flow velocities appear inversely related to the square of vessel diameter representing local fluid dynamics. However, studies of flow velocity-diameter relationships are few, and may identify vessels for which diameter changes are better correlated with Doppler velocity. We therefore studied a large retrospective cohort with concurrent transcranial Doppler velocities and angiographic vessel diameters. METHODS: This is a single-site, retrospective, cohort study of adult patients with aneurysmal subarachnoid hemorrhage, approved by the UT Southwestern Medical Center Institutional Review Board. Study inclusion required transcranial Doppler measurements within 1.1, R2>0.9). Furthermore, velocity and diameter changed (P<0.033) consistent with the signature time course of cerebral vasospasm. CONCLUSIONS: These results suggest that middle cerebral artery velocity-diameter relationships are most influenced by local fluid dynamics, which supports these vessels as preferred endpoints in Doppler detection of cerebral vasospasm. Other vessels showed less influence of local fluid dynamics, pointing to greater role of factors outside the local vessel segment in determining flow velocity.

Technical Nuances and Outcomes of Telescoping Pipeline Flow Diverters: A Multicenter Study.

BACKGROUND: "Telescoping" multiple overlapping Pipeline Embolization Devices (PEDs; Medtronic) has increased their utility by allowing for more impermeable coverage and providing the ability to off-set landing zone sites and extend treatment constructs. OBJECTIVE: To consider the technical nuances and challenges of telescoping PEDs for the treatment of intracranial aneurysms. METHODS: Databases from 3 U.S. academic neurovascular centers were retrospectively queried to identify patients with intracranial aneurysms treated with multiple PED constructs. Data on patient and aneurysm characteristics, as well as outcomes including Raymond-Roy occlusion classification, modified Rankin Scale score, and complications, were gathered. RESULTS: Forty-six patients had 48 intracranial aneurysms treated, including 16 (33%) in whom placement of telescoping PEDs was planned. Fourteen (30%) patients presented with a ruptured aneurysm. Twenty-one aneurysms (44%) were treated with proximal extension, 13 (27%) with distal extension, and 14 (29%) with PED placement inside one another. Thirty (70%) patients had complete aneurysm occlusion at follow-up. Two (4%) patients had to be retreated. Three patients with unruptured and 1 with ruptured aneurysm had a permanent intraprocedural complication. We present descriptive cases illustrating PEDs that were placed inside one another, proximally, distally, and to improve wall apposition because of vessel tortuosity. CONCLUSION: Our data indicate a higher than expected complication rate that is likely because of the technical complexity of these cases. The case illustrations presented demonstrate the indications and challenging aspects of telescoping PEDs.

Surpass Intracranial Aneurysm Embolization System Pivotal Trial to Treat Large or Giant Wide-Neck Aneurysms - SCENT: 3-year outcomes.

BACKGROUND: To report the 3-year safety and effectiveness of the Surpass Streamline flow diverter in the SCENT trial (Surpass Intracranial Aneurysm Embolization System Pivotal Trial to Treat Large or Giant Wide-Neck Aneurysms). METHODS: The Surpass Streamline flow diverter device was evaluated in a multicenter, prospective, single-arm, non-randomized interventional trial including patients with uncoilable or previously treated but failed aneurysms of the intracranial internal carotid artery. 3-year outcomes were tabulated with descriptive statistics and compared with 1-year outcomes. RESULTS: Of 180 patients in the modified intent-to-treat (mITT) cohort, 36-month clinical and angiographic follow-up was available in 134 and 117 cases, respectively. Effectiveness endpoint of complete aneurysm occlusion without clinically significant stenosis or retreatment was met in 71.8% (79/110, 95% CI 62.4% to 80.0%) of cases. Safety composite endpoint was 12.2% (22/180) over the 3-year period, with two major safety events (ipsilateral ischemic strokes) occurring between 12-36 months. Complete aneurysm occlusion was noted in 77.8% (91/117), and 99.1% (116/117) of the patients demonstrated adequate aneurysm occlusion (complete occlusion or neck residual). There were four cases (2.2%) of aneurysm rupture, all occurring within the first month of the index procedure. Target aneurysm retreatment rate was 2.8% (5/180). CONCLUSION: The present findings support the long-term safety and effectiveness of the Surpass Streamline flow diverter device. TRIAL REGISTRATION: NCT01716117.

Somatic Variants in SVIL in Cerebral Aneurysms.

Background and Objectives: While somatic mutations have been well-studied in cancer, their roles in other complex traits are much less understood. Our goal is to identify somatic variants that may contribute to the formation of saccular cerebral aneurysms. Methods: We performed whole-exome sequencing on aneurysm tissues and paired peripheral blood. RNA sequencing and the CRISPR/Cas9 system were then used to perform functional validation of our results. Results: Somatic variants involved in supervillin (SVIL) or its regulation were found in 17% of aneurysm tissues. In the presence of a mutation in the SVIL gene, the expression level of SVIL was downregulated in the aneurysm tissue compared with normal control vessels. Downstream signaling pathways that were induced by knockdown of SVIL via the CRISPR/Cas9 system in vascular smooth muscle cells (vSMCs) were determined by evaluating changes in gene expression and protein kinase phosphorylation. We found that SVIL regulated the phenotypic modulation of vSMCs to the synthetic phenotype via Krüppel-like factor 4 and platelet-derived growth factor and affected cell migration of vSMCs via the RhoA/ROCK pathway. Discussion: We propose that somatic variants form a novel mechanism for the development of cerebral aneurysms. Specifically, somatic variants in SVIL result in the phenotypic modulation of vSMCs, which increases the susceptibility to aneurysm formation. This finding suggests a new avenue for the therapeutic intervention and prevention of cerebral aneurysms.

CVR-MRICloud: An online processing tool for CO2-inhalation and resting-state cerebrovascular reactivity (CVR) MRI data.

Cerebrovascular Reactivity (CVR) provides an assessment of the brain's vascular reserve and has been postulated to be a sensitive marker in cerebrovascular diseases. MRI-based CVR measurement typically employs alterations in arterial carbon dioxide (CO2) level while continuously acquiring Blood-Oxygenation-Level-Dependent (BOLD) images. CO2-inhalation and resting-state methods are two commonly used approaches for CVR MRI. However, processing of CVR MRI data often requires special expertise and may become an obstacle in broad utilization of this promising technique. The aim of this work was to develop CVR-MRICloud, a cloud-based CVR processing pipeline, to enable automated processing of CVR MRI data. The CVR-MRICloud consists of several major steps including extraction of end-tidal CO2 (EtCO2) curve from raw CO2 recording, alignment of EtCO2 curve with BOLD time course, computation of CVR value on a whole-brain, regional, and voxel-wise basis. The pipeline also includes standard BOLD image processing steps such as motion correction, registration between functional and anatomic images, and transformation of the CVR images to canonical space. This paper describes these algorithms and demonstrates the performance of the CVR-MRICloud in lifespan healthy subjects and patients with clinical conditions such as stroke, brain tumor, and Moyamoya disease. CVR-MRICloud has potential to be used as a data processing tool for a variety of basic science and clinical applications.

Surgical Management of a Massive Frontal Bone Hemangioma: Case Report.

Intraosseous hemangiomas are rare, benign tumors that can arise from the calvarium. These lesions often invade the outer table of the skull, but typically spare the inner table and intracranial structures. En bloc surgical resection is the standard treatment for intraosseous hemangiomas. However, a piecemeal resection may be required to safely remove the tumor in cases involving the inner table to protect the underlying brain parenchyma and vascular structures. Proper reconstruction is critical to optimize the cosmetic outcome, and a staged procedure allowing implantation of a custom-made implant can be considered for large lesions involving the forehead. We present a case of a patient with a large frontal intraosseous hemangioma with intradural involvement to highlight the surgical nuances of resection and review the existing literature regarding optimal management of these patients.

Time trends in the risk of delayed cerebral ischemia after subarachnoid hemorrhage: a meta-analysis of randomized controlled trials.

OBJECTIVE: Delayed cerebral ischemia (DCI) contributes to morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). Continuous improvement in the management of these patients, such as neurocritical care and aneurysm repair, may decrease the prevalence of DCI. In this study, the authors aimed to investigate potential time trends in the prevalence of DCI in clinical studies of DCI within the last 20 years. METHODS: PubMed, Embase, and the Cochrane library were searched from 2000 to 2020. Randomized controlled trials that reported clinical (and radiological) DCI in patients with aSAH who were randomized to a control group receiving standard care were included. DCI prevalence was estimated by means of random-effects meta-analysis, and subgroup analyses were performed for the DCI sum score, Fisher grade, clinical grade on admission, and aneurysm treatment method. Time trends were evaluated by meta-regression. RESULTS: The search strategy yielded 5931 records, of which 58 randomized controlled trials were included. A total of 4424 patients in the control arm were included. The overall prevalence of DCI was 0.29 (95% CI 0.26-0.32). The event rate for prevalence of DCI among the high-quality studies was 0.30 (95% CI 0.25-0.34) and did not decrease over time (0.25% decline per year; 95% CI -2.49% to 1.99%, p = 0.819). DCI prevalence was higher in studies that included only higher clinical or Fisher grades, and in studies that included only clipping as the treatment modality. CONCLUSIONS: Overall DCI prevalence in patients with aSAH was 0.29 (95% CI 0.26-0.32) and did not decrease over time in the control groups of the included randomized controlled trials.

Non-contrast hemodynamic imaging of Moyamoya disease with MR fingerprinting ASL: A feasibility study.

PURPOSE: MR Fingerprinting (MRF) Arterial Spin Labeling (ASL) is a non-contrast technique to estimate multiple brain hemodynamic and structural parameters in a single scan. The purpose of this study is to examine the feasibility and initial utility of MRF-ASL in Moyamoya disease. METHODS: MRF-ASL, conventional single-delay ASL, Time-of-flight (TOF) MR angiography, and contrast-based dynamic-susceptibility-contrast (DSC) MRI were prospectively collected from a group of Moyamoya patients in North America (N = 21, 4 men and 17 women). Sixteen healthy subjects (7 men and 9 women) also underwent an MRF-ASL scan. Cerebral blood flow (CBF), bolus arrival time (BAT), and tissue T1 were compared between Moyamoya patients and healthy controls. Perfusion parameters from MRF-ASL were compared to those from other MRI sequences. Multi-linear regression was used for comparisons of parameter values between Moyamoya and control groups. Linear mixed-effects models was used when comparing MRF-ASL to PCASL and DSC parameters. Spearman's Rank Correlation Coefficient was calculated when comparing MRF-ASL to and MRA grades. A P value of 0.05 or less was considered significant. RESULTS: BAT in stenotic internal carotid artery (ICA) territories was prolonged (P < 0.001) in Moyamoya patients, when compared with healthy controls. CBF in stenotic ICA territories of Moyamoya patients was not different from CBF in healthy controls; but in the PCA territories, CBF in Moyamoya patients was higher (P < 0.01) than controls. Quantitative T1 values in the stenotic ICA territories was longer (P < 0.05) than that in controls. Hemodynamic parameters estimated from MRF-ASL were significantly correlated with single-delay ASL and DSC. Longer BAT was associated with more severe intracranial artery stenosis in ICA. CONCLUSIONS: MRF-ASL is a promising technique to assess perfusion and structural abnormalities in Moyamoya patients.

Perioperative Neurological Evaluation and Management to Lower the Risk of Acute Stroke in Patients Undergoing Noncardiac, Nonneurological Surgery: A Scientific Statement From the American Heart Association/American Stroke Association.

Perioperative stroke is a potentially devastating complication in patients undergoing noncardiac, nonneurological surgery. This scientific statement summarizes established risk factors for perioperative stroke, preoperative and intraoperative strategies to mitigate the risk of stroke, suggestions for postoperative assessments, and treatment approaches for minimizing permanent neurological dysfunction in patients who experience a perioperative stroke. The first section focuses on preoperative optimization, including the role of preoperative carotid revascularization in patients with high-grade carotid stenosis and delaying surgery in patients with recent strokes. The second section reviews intraoperative strategies to reduce the risk of stroke, focusing on blood pressure control, perioperative goal-directed therapy, blood transfusion, and anesthetic technique. Finally, this statement presents strategies for the evaluation and treatment of patients with suspected postoperative strokes and, in particular, highlights the value of rapid recognition of strokes and the early use of intravenous thrombolysis and mechanical embolectomy in appropriate patients.

Cerebrovascular Reactivity Mapping Using Resting-State BOLD Functional MRI in Healthy Adults and Patients with Moyamoya Disease.

Background Cerebrovascular reserve, the potential capacity of brain tissue to receive more blood flow when needed, is a desirable marker in evaluating ischemic risk. However, current measurement methods require acetazolamide injection or hypercapnia challenge, prompting a clinical need for resting-state (RS) blood oxygen level-dependent (BOLD) functional MRI data to measure cerebrovascular reactivity (CVR). Purpose To optimize and evaluate an RS CVR MRI technique and demonstrate its relationship to neurosurgical treatment. Materials and Methods In this HIPAA-compliant study, RS BOLD functional MRI data collected in 170 healthy controls between December 2008 and September 2010 were retrospectively evaluated to identify the optimal frequency range of temporal filtering on the basis of spatial correlation with the reference standard CVR map obtained with CO2 inhalation. Next, the optimized RS method was applied in a new, prospective cohort of 50 participants with Moyamoya disease who underwent imaging between June 2014 and August 2019. Finally, CVR values were compared between brain hemispheres with and brain hemispheres without revascularization surgery by using Mann-Whitney U test. Results A total of 170 healthy controls (mean age ± standard deviation, 51 years ± 20; 105 women) and 100 brain hemispheres of 50 participants with Moyamoya disease (mean age, 41 years ± 12; 43 women) were evaluated. RS CVR maps based on a temporal filtering frequency of [0, 0.1164 Hz] yielded the highest spatial correlation (r = 0.74) with the CO2 inhalation CVR results. In patients with Moyamoya disease, 77 middle cerebral arteries (MCAs) had stenosis. RS CVR in the MCA territory was lower in the group that did not undergo surgery (n = 30) than in the group that underwent surgery (n = 47) (mean, 0.407 relative units [ru] ± 0.208 vs 0.532 ru ± 0.182, respectively; P = .006), which is corroborated with the CO2 inhalation CVR data (mean, 0.242 ru ± 0.273 vs 0.437 ru ± 0.200; P = .003). Conclusion Cerebrovascular reactivity mapping performed by using resting-state blood oxygen level-dependent functional MRI provided a task-free method to measure cerebrovascular reserve and depicted treatment effect of revascularization surgery in patients with Moyamoya disease comparable to that with the reference standard of CO2 inhalation MRI. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Wolf and Ware in this issue.