Cerebrovascular Reserve In Patients Research Articles

ASL-MRI-guided evaluation of multiple burr hole revascularization surgery in Moyamoya disease

PurposeMoyamoya (MM) disease is characterized by progressive intracranial arterial stenosis. Patients commonly need revascularization surgery to optimize cerebral blood flow (CBF). Estimation of CBF and cerebrovascular reserve (CVR) is therefore necessary before and after surgery. However, assessment of CBF before and after indirect revascularization surgery with the multiple burr hole (MBH) technique in MM has not been studied extensively. In this study, we describe our initial experience using arterial spin labeling magnetic resonance perfusion imaging (ASL-MRI) for CBF and CVR assessment before and after indirect MBH revascularization surgery in MM patients.MethodsEleven MM patients (initial age 6–50 years, 1 male/10 female) with 19 affected hemispheres were included. A total of 35 ASL-MRI examinations were performed using a 3D-pCASL acquisition before and after i.v. acetazolamide challenge (1000 mg in adults and 10 mg/kg in children). Twelve MBH procedures were performed in seven patients. The first follow-up ASL-MRI was performed 7–21 (mean 12) months after surgery.ResultsBefore surgery, CBF was 46 ± 16 (mean ± SD) ml/100 g/min and CVR after acetazolamide challenge was 38.5 ± 9.9 (mean ± SD)% in the most affected territory (middle cerebral artery). In cases in which surgery was not performed, CVR was 56 ± 12 (mean ± SD)% in affected hemispheres. After MBH surgery, there was a relative change in CVR compared to baseline (preop) of + 23.5 ± 23.3% (mean ± SD). There were no new ischemic events.ConclusionUsing ASL-MRI we followed changes in CBF and CVR in patients with MM. The technique was encouraging for assessments before and after revascularization surgery.

Evaluation of single-delay arterial spin labeling-based spatial coefficient of variation and histogram-based parameters in relation to cerebrovascular reserve in patients with Moyamoya disease.

Single-delay Arterial Spin Labeling (ASL)-based spatial coefficient of variation (CoVCBF) has been suggested as a measure of hemodynamic disturbance in patients with cerebrovascular diseases. However, spatial CoVCBF and other histogram-based parameters such as skewness and kurtosis and the volume of the arterial transit time artefact (ATAvol), has not been evaluated in patients with MMD nor against cerebrovascular reserve (CVR). The aim of this study was to assess whether any associations between spatial CoVCBF, skewness, kurtosis, and ATAvol are present and to analyze any potential associations with CVR, derived from single-delay ASL in patients with MMD. Fifteen MMD patients were included before or after revascularization surgery. Cerebral blood flow (CBF) maps were acquired using pseudo-continuous ASL before, and 5, 15, and 25 min after an intravenous acetazolamide injection. CVRmax was defined as the highest percentual increase in CBF at any of the three post-injection time points. A vascular territory template was spatially normalized to each patient, including the bilateral anterior, middle, and posterior cerebral arteries. All affected anterior and middle cerebral artery regions and all unaffected posterior cerebral artery regions were included, based on Suzuki grading by digital subtraction angiography. Significant differences between affected and unaffected regions were found for CBF, CVRmax, and ATAvol. No association was found between CVRmax and any other parameter. High correlations were found between spatial CoVCBF, skewness and ATAvol. Spatial CoVCBF derived from single-delay ASL does not correlate with CVR in patients with MMD. Moreover, skewness and kurtosis did not provide additional information of clinical value.

Abstract TP95: Utility Of Automated Artificial Intelligence Software In The Analysis Of Ct Perfusion With Acetazolamide Challenge For The Assessment Of Cerebrovascular Reserve In Patients With Cervico-cranial Arterial Stenoses And Occlusions

Background: Cerebrovascular reserve (CVR) assessment is valuable in predicting stroke risk in patients with cranio-cervical stenoses and occlusions. CTP with Acetazolamide challenge (AC) allows a qualitative and quantitative assessment of CVR but is limited by ROI positioning, motion and software. Artificial intelligence (AI) automated software with delay in arrival correction has been validated for the processing of CTP data for acute stroke and may more easily detect abnormal CVR. We sought to compare the results of image-processing with a standard platform (Vitrea™) and AI platform (RAPID™). Methods: Retrospective analysis of an IRB approved prospective database of patients who had CTP with acetazolamide (1g IV) who also had a stenosis/occlusion of the internal carotid or middle cerebral arteries was performed. Symptomatic status was defined as recurrent symptoms related to the vessel of interest within 6 months of scan. Two readers, blinded to the clinical scenario, independently reviewed the CTP datasets and identified CBF regional abnormalities and changes post AC using the 2 different platforms. Abnormal CVR was defined as an increase of CBF post AC of <25% of the baseline in the region of interest with Vitrea™, and an expansion of the volume of tissue with CBF<30% using RAPID™. CTP analyses were correlated with the clinical presentation. Results: Thirty patients fulfilling criteria received CTP before and after AC. 24 patients (80%) were symptomatic. Vitrea™ detected decrease in CBF pre-AC in 27 patients and worsening CBF value post-AC in 19 patients. 10 Patients had an increase >25% in CBF post AC. Rapid™ detected 5 patients with CBF lesion <30% pre-AC. Expansion of the CBF lesion occurred in 8 patients post-AC with a mean change in volume of 7.7 ml (P-value=0.002). The sensitivity for the detection of poor CVR in patients with recurrent symptoms was 80% (95% CI 59.30 - 93.17) with Vitrea™ and 45% (95% CI 25.55%-67.18%) with RAPID™. Conclusion: Automated post processing software with delay in arrival correction algorithm is less sensitive to abnormal CVR and has lower correlation with clinical presentation in this small cohort. Further study is warranted to identify thresholds that may better correlate.

Abstract TMP66: Correlation Of Cerebrovascular Reserve Assessed By Acetazolamide-stress Spect With Collaterals On Arterial Spin-labeling MRI In Patients With Carotid Occlusive Disease

Introduction: We investigated the relationship between the level of cerebral collateral circulation on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) and cerebrovascular reserve (CVR) on acetazolamide (ACZ)-stress single photon emission computed tomography (SPECT) brain scans in internal carotid artery (ICA) stenosis. Methods: This study enrolled 129 patients with severe ICA stenosis (>70%). Collateral circulation was assessed in pulsed ASL images based on the presence of arterial transit artifact (ATA) that late-arriving flow appears as serpiginous high ASL signal within cortical vessels. CVR based on rest-SPECT and ACZ-stress SPECT with Tc-99m-ECD was calculated. The ASL CBF maps were independently assessed by two neuroradiologists blinded to clinical information. The two neuroradiologists graded on two slices of ASL images corresponding to Alberta Stroke Program Early Computed Tomography Score (ASPECTS) location using a 4-point scale for ASL intensity. Results: With ACZ-stress SPECT, the 88/129 (68%) patients showed normal CVR and 41/129 (32%) patients showed decreased CVR. In 73/88 (82%) of the normal CVR group patients, ASL showed ATA in ipsilateral to the stenosis. In 19/41 (46%) of the decreased CVR group patients, ASL showed no evidence of ATA in ipsilateral to the stenosis. Significant positive relationship was observed between the normal CVR group and the ATA showing group in ICA stenosis patients (p = 0.001, chi-square test). The ASL-based ASPECTS scores of brain in the ipsilateral side was lower than the scores in the contralateral side to the ICA stenosis (p < 0.0001, Wilcoxon signed rank test). The ASL-based ASPECTS scores of brain ipsilateral side to the ICA stenosis was lower in the reduced CVR group than normal CVR group (p = 0.005). Conclusion: This study demonstrated the statistically significant positive correlation between good collaterals on ASL MRI and intact CVR in patients with ICA stenosis.

Correlation between cognitive function and cerebrovascular reserve in patients with steno-occlusive disease of a main cerebral artery

Correlation between cognitive function and cerebrovascular reserve in patients with steno-occlusive disease of a main cerebral artery

Effect and safety of acupuncture on cerebrovascular reserve in patients with acute cerebral infarction: A protocol for systematic review and meta-analysis.

Background:As far as we know, no evidence has been established to assess the effects of acupuncture for acute cerebral infarction patients. Therefore, this systematic review and meta-analysis will be conducted to assess the efficacy and safety of acupuncture on cerebrovascular reserve in patients with acute cerebral infarction.Methods:On June 20, 2021, the authors will perform a preliminary search in the PubMed, Embase, and Scopus databases using the following keywords: “acupuncture,” “acute cerebral infarction.” We will also examine the Clinical Trials Registry for other ongoing and unpublished studies. The inclusion criteria included (1) patients with acute cerebral infarction, (2) patients who received acupuncture, and (3) studies assessed cerebrovascular reserve, breath-holding index, Barthel index, and adverse events. All English language randomized controlled trials published within the last 20 years were eligible for inclusion. Primary outcome measures in our study are cerebrovascular reserve, and secondary outcome measures include the breath-holding index, Barthel index, and adverse events. All outcomes are pooled on a random-effect model.Results:The results of this research will be delivered in a peer-reviewed journal.OSF registration number:10.17605/OSF.IO/7M4BK.

Abstract WMP41: The Value of Arterial Spin-Labeling Imaging in the Cerebral Collateral Circulation Evaluation of Carotid Occlusive Disease; Correlation Study With Acetazolamide-Stress Single Photon Emission Computed Tomography

Introduction: We investigated the relationship between the level of cerebral collateral circulation on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) and cerebrovascular reserve (CVR) on acetazolamide (ACZ)-stress single photon emission computed tomography (SPECT) brain scans in internal carotid artery (ICA) stenosis. Methods: This study enrolled 129 patients with severe ICA stenosis (>70%). Collateral circulation was assessed in pulsed ASL images based on the presence of arterial transit artifact (ATA) that late-arriving flow appears as serpiginous high ASL signal within cortical vessels. CVR based on rest-SPECT and ACZ-stress SPECT with Tc-99m-ECD was calculated. The ASL CBF maps were independently assessed by two neuroradiologists blinded to clinical information. The two neuroradiologists graded on two slices of ASL images corresponding to Alberta Stroke Program Early Computed Tomography Score (ASPECTS) location using a 4-point scale for ASL intensity. Results: With ACZ-stress SPECT, the 88/129 (68%) patients showed normal CVR and 41/129 (32%) patients showed decreased CVR. In 73/88 (82%) of the normal CVR group patients, ASL showed ATA in ipsilateral to the stenosis. In 19/41 (46%) of the decreased CVR group patients, ASL showed no evidence of ATA in ipsilateral to the stenosis. Significant positive relationship was observed between the normal CVR group and the ATA showing group in ICA stenosis patients (p = 0.001, chi-square test). The ASL-based ASPECTS scores of brain in the ipsilateral side was lower than the scores in the contralateral side to the ICA stenosis (p < 0.0001, Wilcoxon signed rank test). The ASL-based ASPECTS scores of brain ipsilateral side to the ICA stenosis was lower in the reduced CVR group than normal CVR group (p = 0.005). Conclusion: This study demonstrated the statistically significant positive correlation between good collaterals on ASL MRI and intact CVR in patients with ICA stenosis.

Occlusive radiation cerebral vasculopathy implies medical complexity: a case report

BackgroundCranial irradiation is one of the main treatment modalities for central nervous system tumors. It carries many complications, one being occlusive radiation vasculopathy of large vessels. It is an underrecognized etiology for stroke, especially in the younger population. The pathophysiological process is controversial, but there is much literature supporting the theory of its being a secondary form of moyamoya disease.Case presentationA 31-year-old Caucasian man with a history of pineal blastoma at the age of 3 years, which was treated with resection, radiotherapy, and chemotherapy, presented to our institution with right M1 stroke. Further assessment by computed tomographic perfusion study with acetazolamide demonstrated steal phenomenon of the right middle cerebral artery territory (type III response) with a small internal region of matched cerebral blood volume defect (that is, infarct core). Coincidentally, he was found to have multiple brain masses consistent with meningiomas. Occlusive radiation vasculopathy was the most likely culprit of the patient’s stroke. The patient was treated medically with “baby” acetylsalicylic acid and clopidogrel for 3 months, then continued only on baby acetylsalicylic acid.ConclusionLate-onset occlusive radiation vasculopathy is a potentially severe iatrogenic manifestation of radiotherapy that requires a high index of suspicion as an etiology of stroke in young population, especially those with coexistent meningioma that might be a strong indicator for occlusive radiation vasculopathy as the stroke culprit. We reviewed the available literature to better understand the pathogenesis, clinical presentation, and treatment options of occlusive radiation vasculopathy. Applying perfusion studies with acetazolamide measures the cerebrovascular reserve in patients with occlusive radiation vasculopathy, which could help in determining the appropriate available treatment option.

Predictive Value of Cerebrovascular Reserve in Patients with Carotid Artery Stenosis for Choosing Treatment Strategy

The choice of treatment of carotid artery stenosis is firstly based on assessment of the degree of stenosis and embologeneity of the atherosclerotic plaque. But even in 'good-risk' population it is still difficult to identify the patients who are particularly at high threat of stroke and would most benefit from carotid reconstruction. Along with common criteria numerous studies also focus on a prognostic role of a cerebrovascular reserve (CVR) and its state which allows to carry out more objective and pathogenetically substantiated selection of cases for surgical and medical treatment.

Evaluation of cerebrovascular reserve in patients with cerebrovascular diseases using resting-state MRI: A feasibility study

PurposeTo demonstrate the feasibility of mapping cerebrovascular reactivity (CVR) using resting-state functional MRI (fMRI) data without gas or other challenges in patients with cerebrovascular diseases and to show that brain regions affected by the diseases have diminished vascular reactivity. Materials and methodsTwo sub-studies were performed on patients with stroke and Moyamoya disease. In Study 1, 20 stroke patients (56.3 ± 9.7 years, 7 females) were enrolled and resting-state blood‑oxygenation-level-dependent (rs-BOLD) fMRI data were collected, from which CVR maps were computed. CVR values were compared across lesion, perilesional and control ROIs defined on anatomic images. Reproducibility of the CVR measurement was tested in 6 patients with follow-up scans. In Study 2, rs-BOLD fMRI and dynamic susceptibility contrast (DSC) MRI scans were collected in 5 patients with Moyamoya disease (32.4 ± 8.2 years, 4 females). Cerebral blood flow (CBF), cerebral blood volume (CBV), and time-to-peak (TTP) maps were obtained from the DSC MRI data. CVR values were compared between stenotic brain regions and control regions perfused by non-stenotic arteries. ResultsIn stroke patients, lesion CVR (0.250 ± 0.055 relative unit (r.u.)) was lower than control CVR (0.731 ± 0.088 r.u., p = 0.0002). CVR was also lower in the perilesional regions in a graded manner (perilesion 1 CVR = 0.422 ± 0.051 r.u., perilesion 2 CVR = 0.492 ± 0.046 r.u.), relative to that in the control regions (p = 0.005 and 0.036, respectively). In the repeatability analysis, a strong correlation was observed between lesion CVR (r2 = 0.91, p = 0.006) measured at two time points, as well as between control CVR (r2 = 0.79, p = 0.036) at two time points. In Moyamoya patients, CVR in the perfusion deficit regions delineated by DSC TTP maps (0.178 ± 0.189 r.u.) was lower than that in the control regions (0.868 ± 0.214 r.u., p = 0.013). Furthermore, the extent of reduction in CVR was significantly correlated with the extent of lengthening in TTP (r2 = 0.91, p = 0.033). ConclusionOur findings suggested that rs-BOLD data can be used to reproducibly evaluate CVR in patients with cerebrovascular diseases without the use of any vasoactive challenges.

Abstract 138: Correlation of Cerebrovascular Reserve Assessed by Acetazolamide-stress SPECT With Collaterals on Arterial Spin-labeling MRI in Patients With Carotid Occlusive Disease

Purpose: We evaluated the correlation between cerebrovascular reserve (CVR) on acetazolamide (ACZ) -stress single photon emission computed tomography (SPECT) brain scans and collaterals on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) in internal carotid artery (ICA) stenosis. Materials and Methods: 86 patients with ICA stenosis (>70%) were enrolled in this study. Including pulsed ASL, MRI was acquired on a 3 tesla system. On ASL, late-arriving flow appears as serpiginous high ASL signal within cortical vessels, which has been termed arterial transit artifact (ATA). Images were interpreted for the presence of ATA. 82/86 ICA stenosis patients underwent SPECT imagings with Tc-99m-ECD in the resting and after ACZ challenge. We observed the presence of intracranial collaterals, which are manifested by ATA, on ASL brain perfusion scan. CVR based on rest-SPECT and ACZ-stress SPECT was calculated. With ACZ-stress SPECT, the 82 patients were grouped as either showing or not showing evidence of decreased CVR. We assessed the relationship between reduced CVR and intracranial collaterals shown as ATA on ASL brain perfusion. Results: In 61/86 (70%) of the ICA stenosis patients, ASL showed ATA in ipsilateral to the stenosis. With acetazolamide stress SPECT, the 27/82 (32%) patients showed evidence of decreased CVR. In 45/55 (81%) of the normal CVR group and 16/27 (59%) of the reduced CVR from the SPECT results, pulsed ASL showed ATA in ipsilateral to the stenosis. Significant positive relationship was observed between normal CVR group and ATA showing group in ICA stenosis patients on ASL brain perfusion (p=0.035, chi-square test). Conclusion: The ATA with ASL imaging as a noninvasive and no contrast demanding technique, can depict slow flow in excellent collateral vessels and has clinical utility in detecting CVR in patients with ICA stenosis.

Predictors of poor cerebral collaterals and cerebrovascular reserve in patients with chronic total carotid occlusion

Background: This study aims to investigate the relationship between cerebrovascular reserve (CVR) capacity, as measured by single-photon emission computed tomography (SPECT) and collateral blood flow, according to a transcranial colour-coded duplex(TCCD), in patients with symptomatic total carotid occlusion (TCO). Additionally, the study aims to determine whether vascular risk factors have an effect on collateral blood flow, as well as on the CVR.Methods: Thirty-four patients with chronic TCO, diagnosed by carotid duplex scanning and confirmed by other vascular imaging modalities, who had ischaemic symptoms either as stroke or transient ischaemic attack, were subjected to clinical assessment, SPECT under dipyridamole stress, and grading of cerebral collateral blood flow using TCCD. Demographics and vascular risk factors were correlated with SPECT and TCCD findings.Results: CVR showed a significant positive correlation with the intensity of collaterals with P value <0.001 and a Spearman correlation coefficient of 0.686. Hypertension was the only predictor of poor collaterals (p value =0.049; OR =11.5 with 95% CI 1.01–131.16).Smoking was predictive of poor CVR as measured by qualitative SPECT (p value =0.02; OR =13.2 with 95% CI 1.4–120.6).Conclusion: Cerebral collaterals have an important role in the maintenance of CVR in patients with TCO. Preventive measures should be directed towards hypertension and smoking to preserve cerebral collateral patency and consequently improve CVR in patients with TCO.

Reduced Cerebrovascular Reserve Capacity in Adults with Sickle Cell Disease

Introduction: Sickle Cell Disease (SCD) is frequently complicated by stroke. Although transcranial Doppler effectively identifies children at risk for stroke, adult patients do not benefit from this test. In SCD, chronic hemolytic anemia leads to cerebral vasodilation, elevated cerebral blood flow (CBF) and subsequently, impaired cerebrovascular reserve (CVR) capacity. CVR represents the maximum increase in CBF in response to metabolic stressors. CVR mapping is a promising imaging biomarker for stroke risk assessment, potentially identifying patients with preclinical hemodynamic impairment. Our laboratory performs CVR mapping by measuring CBF prior to and following maximum cerebral vasodilation with acetazolamide (ACZ). The primary aim of this study was to quantitatively assess CVR in adult patients with SCD compared to healthy controls.Methods: Adult SCD patients (HbSS/HbSβ0) were recruited for this IRB-approved study with ACZ-induced vasodilation and venous blood sampling. Patients with a history of clinically overt stroke were excluded. Controls were selected from patients' friends and family members without SCD and matched on age, sex, and race. The following MRI images were acquired at 3T (Philips Healthcare, Best, NL): time of flight MRA for visualization of major cerebral vessels, T2 FLAIR for manual segmentation of white matter hyperintensities (WMHs), and pseudo-continuous arterial spin labeling (ASL) for CBF assessment. CBF was measured at baseline and 10min post ACZ (16mg/kg intravenous infusion over 3min). MRI images were processed with the ExploreASL toolbox, to obtain registered maps of quantified CBF and CVR (% change in CBF). We measured T1blood in each subject to improve quantification accuracy as these values can differ in SCD. Group comparisons were performed using non-parametric two-sample tests. Correlations were characterized by Spearman's rho (ρ). P<0.05 was considered significant. Median values with interquartile range (IQR) are reported for non-normally distributed variables, otherwise mean and standard deviation are reported.Results: 30 patients with SCD (mean age 33±12y,19M) and 11 controls (mean age 37±15y, 6M) were included in this cross-sectional controlled cohort study. Mean hemoglobin levels in patients with SCD were 8.8±1.4 g/dL and in healthy controls were 13.7±1.3 g/dL. Patients with SCD had higher baseline CBF compared to healthy controls (median 73(IQR:25) vs 42(IQR:6) mL/100g/min, p<0.001, F1a). CBF was inversely related to hemoglobin (ρ=-0.84, p<0.001, F1b). ACZ elicited an increase in CBF(p<0.001) which was similar in magnitude in both groups (patients 29±16, controls 35±11, mL/100g/min, F1c), resulting in a lower mean CVR in patients compared to controls (41±24% vs 81±27%, p<0.001, F1d). Baseline CBF predicted CVR (ρ=-0.68, p<0.001, F1e). WMHs were present in both groups, and WMH volume correlated with age (ρ = 0.54, p<0.001). There were no statistical associations between WMH volume and CVR (ρ = -0.15, p=0.4) or CBF(ρ = 0.02, p=0.9), however, two patients with the largest WMH volume (>6 mL) had the lowest CVR (<20%).Discussion: This study shows that regional CVR can be measured using ASL-MRI with ACZ challenge. ACZ was well-tolerated and elicited a robust cerebrovasodilatory response in both groups. However, the relative increase in oxygen delivery (CVR) was much lower in SCD patients, which suggests that patients with SCD have nearly maximal cerebrovascular dilation at baseline. Our data suggest that chronic vasodilation due to anaemia has let to outward remodelling of vessels in adult patients, permitting a larger vascular bed to compensate their anemia. Our premise is that resting O2 delivery is normal in SCD patients; we showed that increasing CBF overcomes severe anemia. However, high resting CBF limits the brain's ability to recruit additional O2 under times of stress. SCD patients have many transient interruptions in O2 delivery including aplastic crisis, splenic sequestration and sleep apnea, as well as metabolic stressors such as fever, sickle cell crisis, infection, and seizure. While baseline CBF predicted global CVR, ASL provides information regarding regional O2 delivery that may offer insight into distribution of ischemic white matter damage. Further study is needed to determine the impact of blood transfusions and hydroxyurea on CVR and whether there is a critical CVR threshold that predicts stroke risk. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Effect of acupuncture on cerebrovascular reserve in patients with acute cerebral infarction: protocol for a randomized controlled pilot study

BackgroundThe incidence of cerebral infarction has been growing year by year in China and around the world. According to clinical observation, acupuncture utilizing the “waking up the spirit” needling method is widely used in patients with cerebral infarction, though the underlying mechanisms remain unclear. Additionally, a number of studies have begun to focus on the relationship between cerebrovascular reserve (CVR) and cerebral infarction. The present study aims to investigate whether CVR is one of potential mechanisms underpinning this effect of acupuncture on patients with cerebral infarction.MethodsThis is a single-centre, prospective, single-blinded, randomized controlled pilot study. Sixty eligible patients will be randomized into an intervention group (waking up the spirit acupuncture) and a control group (hand and foot 12-meridian acupuncture) in a 1:1 ratio. All treatments will be conducted once a day on weekdays followed by a 2-day rest period on the weekend, over a total treatment course of 2 weeks. The primary outcome measures are cerebrovascular reserve (CVR) capacity and Breath-holding Index (BHI) which will be evaluated at baseline and 2 weeks after the first acupuncture treatment, and the secondary outcome measures are National Institutes of Health Stroke Scale (NIHSS) and Barthel Index scores which will be used to further evaluate the efficacy of the intervention.DiscussionCerebrovascular reserve is an independent risk factor for the occurrence, progression, and recurrence of cerebral infarction that requires attention. This trial aims to investigate whether acupuncture utilizing the waking up the spirit needling method can improve CVR capacity in patients with acute cerebral infarction, thus reducing NIHSS scores and preventing further progression of the disease. Furthermore, data and evidence gained from this study will be utilized in the development of future research projects regarding the effects of acupuncture in patients with acute cerebral infarction.Trial registrationISRCTN, ID: ISRCTN99117074. Registered on 20 April 2016.

Evaluation of cerebrovascular reserve in patients undergoing carotid artery stenting and its usefulness in predicting significant hemodynamic changes during temporary carotid occlusion.

We investigated the usefulness of cerebrovascular reserve (CVR) testing to predict severe hemodynamic changes during proximally protected carotid artery stenting. Of 90 patients referred, 63 eligible underwent complete evaluation of the extent of carotid artery disease and transcranial Doppler ultrasound (TCD) assessment of CVR by means of a breath-holding test and ophthalmic artery flow pattern evaluation. Periprocedural TCD monitoring of the ipsilateral middle cerebral artery flow was performed in 24 patients undergoing proximally protected procedure (requiring induction of flow arrest within internal carotid artery). Abnormal CVR was significantly less common in patients with unilateral compared to bilateral carotid artery disease (26.3 % vs. 76.9 %, p=0.02), while ophthalmic artery flow reversal was rare in patients with unilateral carotid artery disease (2.5 % vs. 42.9 %, p<0.01). During the induction of carotid flow arrest, the average mean flow velocity drop following external carotid artery occlusion was low (3.5 %, p=0.67) compared to the induction of complete flow arrest (32.8 %, p<0.01). Six patients had a total mean flow velocity drop >50 %, including 2 patients with normal pre-procedural CVR. Our results suggest that TCD evaluation of CVR is not a reliable predictor of hemodynamic changes induced during proximally protected carotid artery stenting in patients with unilateral carotid artery disease.

CO2BOLD assessment of moyamoya syndrome: Validation with single photon emission computed tomography and positron emission tomography imaging.

AIMTo compare the assessment of cerebrovascular reserve (CVR) using CO2BOLD magnetic resonance imaging (MRI) vs positron emission tomography (PET) and single photon emission computed tomography (SPECT) as reference standard.METHODSTen consecutive patients (8 women, mean age of 41 ± 26 years) with moyamoya syndrome underwent 14 pre-surgical evaluations for external-internal carotid artery bypass surgery. CVR was assessed using CO2BOLD and PET (4)/SPECT (11) with a maximum interval of 36 d, and evaluated by two experienced neuroradiologists.RESULTSThe inter-rater agreement was 0.81 for SPECT (excellent), 0.43 for PET (fair) and 0.7 for CO2BOLD (good). In 9/14 cases, there was a correspondence between CO2BOLD and PET/SPECT. In 4/14 cases, CVR was over-estimated in CO2BOLD, while in 1/14 case, CVR was underestimated in CO2BOLD. The sensitivity of CO2BOLD was 86% and a specificity of 43%.CONCLUSIONCO2BOLD can be used for pre-surgical assessment of CVR in patients with moyamoya syndrome and combines the advantages of absent irradiation, high availability of MRI and assessment of brain parenchyma, cerebral vessels and surrogate CVR in one stop.

Reduced CMRO₂ and cerebrovascular reserve in patients with severe intracranial arterial stenosis: a combined multiparametric qBOLD oxygenation and BOLD fMRI study.

Multiparametric quantitative blood oxygenation level dependent (mqBOLD) magnetic resonance Imaging (MRI) approach allows mapping tissular oxygen saturation (StO2 ) and cerebral metabolic rate of oxygen (CMRO2 ). To identify hemodynamic alteration related to severe intracranial arterial stenosis (SIAS), functional MRI of cerebrovascular reserve (CVR BOLD fMRI) to hypercapnia has been proposed. Diffusion imaging suggests chronic low grade ischemia in patients with impaired CVR. The aim of the present study was to evaluate how oxygen parameters (StO2 and CMRO2 ), assessed with mqBOLD approach, correlate with CVR in patients (n = 12) with SIAS and without arterial occlusion. The perfusion (dynamic susceptibility contrast), oxygenation, and CVR were compared. The MRI protocol conducted at 3T lasted approximately 1 h. Regions of interest measures on maps were delineated on segmented gray matter (GM) of middle cerebral artery territories. We have shown that decreased CVR is spatially associated with decreased CMRO2 in GM of patients with SIAS. Further, the degree of ipsilateral CVR reduction was well-correlated with the amplitude of the CMRO2 deficit. The altered CMRO2 suggests the presence of a moderate ischemia explained by both a decrease in perfusion and in CVR. CVR and mqBOLD method may be helpful in the selection of patients with SIAS to advocate for medical therapy or percutaneous transluminal angioplasty-stenting.

Reduced Contralateral Cerebrovascular Reserve in Patients with Unilateral Steno-Occlusive Disease

The purpose of this study was to evaluate cerebrovascular reactivity (CVR) of major arterial vascular territories, particularly in the contralateral hemodynamically unaffected hemisphere, in patients with unilateral internal carotid artery (ICA) steno-occlusive disease compared to control subjects with risk factors for cerebrovascular disease. Methods: In this retrospective observational study, twenty-seven patients with right-sided unilateral ICA steno-occlusive disease (age range, 25 to 91 years; 17 males) and twenty-one patients with left-sided unilateral ICA steno-occlusive disease (age range, 24 to 83 years; 14 males) and 41 control subjects were studied. CVR was quantitated as the change in blood oxygen level dependent (BOLD) MRI signal (as a surrogate of cerebral blood flow), in response to a consistently applied step change in the arterial partial pressure of carbon dioxide (PaCO₂). The CVR of each major arterial vascular territory was assessed in the ipsilateral hemodynamically affected hemisphere and compared to the corresponding territory in the contralateral hemisphere. Results: In patients, a significant reduction in CVR was observed in the ipsilateral anterior circulation compared to that of the corresponding territory on the contralateral side (0.027 ± 0.083 vs. 0.109 ± 0.066% BOLD change/​mm Hg, p < 0.0001) and to controls (0.195 ± 0.054% BOLD change/mm Hg, p < 0.0001). The CVR of the contralateral anterior circulation was reduced on average by 50% compared to controls (p < 0.0001). Conclusions: The implication of these findings is that unilateral carotid stenosis affects the vascular reserve of both sides of the brain compared to control subjects. This indicates that the collateral blood flow support from the contralateral to the ipsilateral hemisphere comes at a cost of reduced reserve capacity in the contralateral hemisphere. The findings suggest that there may be a reduction in functional hyperemia associated with neuronal activation, not only affecting the hemisphere ipsilateral to an occlusion, but also the hemisphere contralateral to an occlusion. It remains to be determined if ‘stealing' from the ‘rich' to support the ‘poor' has clinical consequences over the long term.

Evaluation of cerebrovascular reserve using xenon-enhanced CT scanning in patients with symptomatic middle cerebral artery stenosis

Cerebrovascular reserve (CVR) is an important prognostic factor in patients with major cerebral arterial steno-occlusive disease. However, few studies have examined CVR in symptomatic intracranial stenosis without ipsilateral extracranial internal carotid artery stenosis. This study sought to evaluate CVR in patients with symptomatic middle cerebral artery (MCA) stenosis using xenon-enhanced computed tomography (Xe/CT) with acetazolamide (ACZ) challenge. Twelve patients with symptomatic MCA stenosis were recruited. All patients were examined by Xe/CT to quantitatively measure resting cerebral blood flow (CBF) and received ACZ challenge to evaluate CVR. For resting CBF, no significant differences were found between the sides in four regions of interest. After the ACZ challenge test, the CVR was significantly different between hemispheres (ipsilateral versus contralateral CVR: 12.9±24.3% versus 28.0±16.8%, respectively; p=0.005) and in the MCA territory (ipsilateral versus contralateral CVR: 8.7±24.7% versus 29.3±24%, respectively; p=0.003). However, no significant differences in CVR were detected between cortical comparisons and white matter comparisons from the two sides. Thus, ACZ-challenge Xe/CT is useful for the measurement of CBF and CVR in these patients. Impaired CVR is an important characteristic of patients with symptomatic MCA stenosis.

E-010 Prolonged Neurologic Deterioration Following Acetazolamide Testing in the Acute Phase Following Ischaemic Stroke

BackgroundAcetazolamide induces cerebral vasodilatation and may be used to measure cerebrovascular reserve in patients with cerebral arteriopathy. While acetazolamide is known to induce transient neurologic deficits as a result of...