Cerebrovascular Reactivity

This volume provides a comprehensive overview of the methodology, physiology, and contemporary and novel applications of cerebrovascular reactivity (CVR) measurements.

Cerebrovascular Reactivity

This volume provides a comprehensive overview of the methodology, physiology, and contemporary and novel applications of cerebrovascular reactivity (CVR) measurements. The chapters in this book cover topics such as an introduction of the neurophysiology, neuroimaging, and clinical methods for CVR measurement; the use of CVR methods in the study of aging, cerebrovascular dysfunction, dementia, and brain tumors; and recommendations for measurement protocols and future applications in clinical translation. In Neuromethods series style, chapters include the kind of detail and key advice from the specialists needed to get successful results in your research center and clinical investigation. Thorough and comprehensive, Cerebrovascular Reactivity: Methodological Advances and Clinical Applications is a valuable tool that provides researchers in neuroscience and neurology with the latest resources on the measurement, interpretation, and application of CVR measurement.

Imaging Cerebrovascular Reactivity Physiology Physics and Therapy

Topic Editor Prof. James Duffin contributed to the development of an automated end-tidal targeting device, RespirActTM and is employed by Thornhill Medical Inc. (Toronto, Canada).

Imaging Cerebrovascular Reactivity  Physiology  Physics and Therapy

Topic Editor Prof. James Duffin contributed to the development of an automated end-tidal targeting device, RespirActTM and is employed by Thornhill Medical Inc. (Toronto, Canada). RespirActTM is currently a non-commercial research tool assembled and made available by TMI to research institutions to enable CVR studies. All other Topic Editors declare no competing interests with regards to the Research Topic subject.

QUANTITATIVE ASSESSMENT OF CEREBROVASCULAR REACTIVITY USING BRAIN SPECT

Background and Aims: The study aimed to develop the quantitative cerebrovascular reactivity (CVR) assessment tool using acetazolamide (ACZ) single photon emission computed tomography (SPECT), helping in the treatment and/or prevention of ...

QUANTITATIVE ASSESSMENT OF CEREBROVASCULAR REACTIVITY USING BRAIN SPECT

Background and Aims: The study aimed to develop the quantitative cerebrovascular reactivity (CVR) assessment tool using acetazolamide (ACZ) single photon emission computed tomography (SPECT), helping in the treatment and/or prevention of cerebrovascular diseases and playing a role as a useful tool for communication between doctors as well as patients. Methods: The quantitative CVR (qCVR) is measured with the ratio of u2018Base-SPECTu2019 and u2018ACZ-SPECTu2019 data. Automated preprocessing steps for creating CVR map. Here, CVR values were calculated with two approaches, u201cROI-basedu201d and u201cVoxel-basedu201d. The regional CVR (rCVR) value (%) and qCVR (from 0 to 1) were further calculated with the formulas, respectively, to remove individual difference in reactivity, basal blood flow and blood vessel perfusion. Furthermore, the nuclear medical specialists assessed the severity of patients with and without the calculated CVR values. The calculated qCVR values in all ROI regions were also ranked for further analysis.Results: Distribution of qCVR values in all regions of a representative subject was shown in Fig. 1 in which only u201cVoxel-basedu201d CVR provided the CVR distribution.Conclusions: The developed qCVR program provided not only quantitative assessment, but also improved user's convenience by configuring software program with GUI. When the distribution of u201cVoxel-basedu201d CVR values is analyzed, the range of normal subjects would be determined statistically and it would be utilized as a quantitative analysis technique to predict the risk factor related with the reduced range of CVR values in patients.

Cerebrovascular Reactivity Rat Studies in Rheoencephalography

Here we describe a correlative study of cerebra! blood flow (CBF) using global, local CBF and carotid flow measurements. The primary objective of this study was to establish a relationship between REG and CBF autoregulation.

Cerebrovascular Reactivity  Rat Studies in Rheoencephalography

Here we describe a correlative study of cerebra! blood flow (CBF) using global, local CBF and carotid flow measurements. The primary objective of this study was to establish a relationship between REG and CBF autoregulation. Rheoencephalography (REG), a rarely used method to measure CBF, is a potential tool of non-invasive continuous life sign monitoring and detection of early cerebrovascular alteration. However, the anatomical background of REG is not clearly understood. Two experimental studies were undertaken on anesthetized rats to define two CBF measurements: CO2 inhalation, and, clamping of common carotid arteries. Measurement of CBF was taken with REG, laser Doppler flowmetry (LDF), and carotid flow by Doppler ultrasound. Data were off-line processed. During CO2 inhalation, the increases in REG and LDF were significant (p = 0.0001), while carotid flow and systemic arterial pressure decreased. During carotid artery clamping, the decrease in REG and Doppler ultrasound were significant (p = 0.0001).

CONFOUNDING OF ASSESSMENT OF CEREBROVASCULAR REACTIVITY BY CHANGES IN BLOOD PRESSURE DURING BREATH HOLDING AND HYPERVENTILATION IN PATIENTS WITH TIA AND MINOR STROKE

IntroductionImpaired cerebrovascular reactivity (CVR) during breath-hold (BH) and hyperventilation (HV) is associated with cerebrovascular disease, but assessment might be confounded by changes in blood pressure (BP) during BH/HV.

CONFOUNDING OF ASSESSMENT OF CEREBROVASCULAR REACTIVITY BY CHANGES IN BLOOD PRESSURE DURING BREATH HOLDING AND HYPERVENTILATION IN PATIENTS WITH TIA AND MINOR STROKE

IntroductionImpaired cerebrovascular reactivity (CVR) during breath-hold (BH) and hyperventilation (HV) is associated with cerebrovascular disease, but assessment might be confounded by changes in blood pressure (BP) during BH/HV. We identified physiological determinants of CVR in consecutive TIA and minor stroke patients.MethodsAt the Oxford Vascular Study (OXVASC) 1-month follow-up, change (u2206) in middle cerebral artery mean flow velocity (u2206MFV) was measured by transcranial Doppler (TCD) after 30 seconds BH or HV. Two blinded reviewers independently scored quality. Dependence of u2206MFV on change in BP (beat-to-beat - u2206BP) and in end-tidal CO2 (u2206etCO2) was determined by linear regression and across quartiles.ResultsOf 602 patients with adequate bone windows and TCD recorded, 488 (81%) had good quality recordings (available more often in younger participants - 64.6 vs 68.7 years, p

Reduced Cerebrovascular Reactivity May Cause Increased Stroke Risk for Women

Features the full text of an article entitled "Reduced Cerebrovascular Reactivity May Cause Increased Stroke Risk for Women," provided online as a part of the Doctor's Guide, a service of the P\S\L Consulting Group, Inc.

Reduced Cerebrovascular Reactivity May Cause Increased Stroke Risk for Women

Features the full text of an article entitled "Reduced Cerebrovascular Reactivity May Cause Increased Stroke Risk for Women," provided online as a part of the Doctor's Guide, a service of the P\S\L Consulting Group, Inc. Notes that cerebrovascular reactivity decreases in women as they get older and therefore causes greater risk of stroke.

CEREBROVASCULAR REACTIVITY MAPPING WITHOUT GAS CHALLENGE IN PATIENTS WITH ASYMPTOMATIC CAROTID STENOSIS

Cerebrovascular Reactivity (CVR) mapping can be performed using vasoactive challenge, during the acquisition of blood oxygenation level dependent magnetic resonance images (BOLD-MRI).

CEREBROVASCULAR REACTIVITY MAPPING WITHOUT GAS CHALLENGE IN PATIENTS WITH ASYMPTOMATIC CAROTID STENOSIS

Cerebrovascular Reactivity (CVR) mapping can be performed using vasoactive challenge, during the acquisition of blood oxygenation level dependent magnetic resonance images (BOLD-MRI). Impaired CVR in patients with occlusion or stenosis of the carotid artery may contribute to ischemic stroke events. Due to the difficulties of the vasoactive challenge protocol3, our objective was to investigate the efficacy of a recently proposed method using resting-state MRI4 to map CVR of patients with asymptomatic carotid artery stenosis (ACAS). MRI was acquired in a 3T machine at the Clinical Hospital of the University of Su00e3o Paulo (HCFMRP-US). Experiment 1: Four patients with ACAS (table 1) underwent an MRI protocol with two BOLD-based sequences: one during inhalation of carbon dioxide, and one during resting-state. Experiment 2: Eleven patients with ACAS underwent an MRI protocol with BOLD acquisition during resting-state. The study was approved by the research ethics committee of the institution. We showed the possibility to map CVR of patients with ICA stenosis using BOLD-MRI acquired during resting state, i.e., without vasoactive challenge. Results were consistent with the conventional CO2 inhalation-based CVR maps.

EFFECT OF CILOSTAZOL AND ISOSORBIDE MONONITRATE ON CEREBROVASCULAR REACTIVITY IN LACUNAR STROKE THE LACI 1 TRIAL

IntroductionSmall vessel disease (SVD), including lacunar stroke, is associated with alterations in cerebrovascular function.

EFFECT OF CILOSTAZOL AND ISOSORBIDE MONONITRATE ON CEREBROVASCULAR REACTIVITY IN LACUNAR STROKE  THE LACI 1 TRIAL

IntroductionSmall vessel disease (SVD), including lacunar stroke, is associated with alterations in cerebrovascular function. Cilostazol and isosorbide mononitrate (ISMN) have multiple actions that may improve cerebrovascular function and slow or prevent SVD. LACI-1 tested their ability to improve cerebrovascular reactivity (CVR). MethodsLACI-1 randomised patients with lacunar ischaemic stroke to cilostazol alone (100mg bd), ISMN alone (25mg bd) or both drugs immediate or 3 week delayed start (the initial 3 week drug-free period providing a u2018no drug controlu2019). We compared the median change in CVR, measured using hypercapnic BOLD MRI, between the baseline visit and after 8 weeks of treatment, or at end of u2018no drugu2019 period in the delayed start group. ResultsWe randomised 26 participants (mean age 68.5yrs, range 53-83; 44% female). In patients allocated ISMN (n=6) and cilostazol (n=5) CVR increased in the white matter (ISMN 49.5%; Cilostazol 23.6% relative increases) and the grey matter (ISMN 19.5%; Cilostazol 15.2% ). In the both drug and no drug groups CVR declined in white matter (both drugs -14.1%; no drugs -5.8% relative decreases) and grey matter (both drugs -6.8%; no drugs -12.3%). Lower both drugs compliance may be obscuring a treatment effect. There were no significant differences between treatment groups. Further analysis, including by treatment compliance will be performed in time for ESOC. ConclusionsLACI-1 suggests that pharmacological intervention can improve tissue-level CVR; lack of significance likely reflects lack of power. Larger studies are warranted to confirm this finding; the ongoing LACI-2 trial will assess if improved CVR translates to clinical improvements.

Cerebrovascular Reactivity and the FMRI BOLD Response in Cardiorespiratory Fitness

Accumulating evidence indicates that poorer vascular health accelerates cognitive decline and increases the likelihood of dementia in old age.

Cerebrovascular Reactivity and the FMRI BOLD Response in Cardiorespiratory Fitness

Accumulating evidence indicates that poorer vascular health accelerates cognitive decline and increases the likelihood of dementia in old age. Aerobic fitness, as a protective factor against vascular dysfunction, may thus serve to attenuate age-related cognitive pathology. The overarching aim of the current investigations was to determine the impact of cardiorespiratory fitness on cognition and its underlying neural substrates. Sedentary and endurance-trained middle-aged adults underwent general health assessment, neuropsychological testing, and functional magnetic resonance imaging (fMRI) during a working memory task and a hypercapnic (breath-hold) challenge. As compared with sedentary age-matched controls, the endurance-trained adults displayed a trend towards better executive function performance and faster reaction time on the working memory task, indicating enhanced speed of information processing. The neural substrates underlying fitness-related cognitive enhancement were explored by examining the blood oxygen level dependent (BOLD) response to a 2-Back working memory task. Additionally, breath-hold calibration of the working memory task was performed in order reduce vascular variance and provide a closer approximation of the neural contributions to the BOLD signal. After breath-hold calibration, the endurance-trained adults displayed greater working memory-related activation in the right middle frontal gyrus, indicating that fitness likely benefits the neural processes underlying cognition over and above global fitness-related changes in cerebrovascular reactivity. Finally, endothelial function was examined as a potential mechanism underlying fitness-related differences in cerebrovascular reactivity. Peripheral endothelial function failed to predict the BOLD signal to hypercapnia, suggesting that the response may be governed by nonendothelial-dependent vasoregulators. In summary, higher cardiorespiratory fitness at midlife may increase executive function abilities by enabling greater recruitment of neural resources during challenging cognitive tasks. Longitudinal studies will be instrumental in determining if these fitness-related changes are capable of modulating the trajectory of cognitive decline across the lifespan.

Cerebrovascular reactivity (CVR) is a measure of dilation capacity of cerebral vasculature.


CEREBRAL HAEMODYNAMIC PREDICTORS OF CHANGES IN CEREBROVASCULAR REACTIVITY FOLLOWING CAROTID ANGIOPLASTY AND STENTING

Background: Internal carotid artery high grade stenosis is a major cause of stroke.

CEREBRAL HAEMODYNAMIC PREDICTORS OF CHANGES IN CEREBROVASCULAR REACTIVITY FOLLOWING CAROTID ANGIOPLASTY AND STENTING

Background: Internal carotid artery high grade stenosis is a major cause of stroke. Carotid angioplasty and stenting (CAS) is a reasonable approach for treatment of certain patients. Cerebrovascular reactivity (CVR) evaluated through breath holding index test, can assess outcome following CAS. Aim: Evaluate changes in CVR before and after CAS. Subjects and method: Thirty-two patients with 35 symptomatic internal carotid artery high grade stenosis (>70%) were enrolled by the mean of ultrasound screening. Breath holding index test was done using transcranial Doppler ultrasound before and after CAS. Results: The study includes 32 patients (22 males and 10 females). Mean age was 61.91u00b16.59 years. All patients showed increase in mean flow velocity and BHI following CAS (P0.001) on both ipsilateral and contralateral side. Both groups (70-90% and 90% stenosis) showed similar improvement of CVR. Conclusion: CAS improves CVR in all high grades of internal carotid artery stenosis.