scholarly journals Cerebrovascular Reactivity in the Brain White Matter: Magnitude, Temporal Characteristics, and Age Effects

2013 ◽  
Vol 34 (2) ◽  
pp. 242-247 ◽  
Author(s):  
Binu P Thomas ◽  
Peiying Liu ◽  
Denise C Park ◽  
Matthias JP van Osch ◽  
Hanzhang Lu
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
Structural Characteristics ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Tissue Ischemia ◽  
Brain White Matter ◽  
Oxygenation Level ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain

White matter (WM) comprises about half of the brain and its dysfunction is implicated in many brain disorders. While structural properties in healthy and diseased WM have been extensively studied, relatively little is known about the physiology underlying these structural characteristics. Recent advances in magnetic resonance (MR) technologies provided new opportunities to better understand perfusion and microvasculature in the WM. Here, we aim to evaluate vasodilatory capacity of the WM vasculature, which is thought to be important in tissue ischemia and autoregulation. Fifteen younger and fifteen older subjects performed a CO2 inhalation task while blood-oxygenation-level-dependent (BOLD) magnetic resonance imaging (MRI) images were continuously collected. The cerebrovascular reactivity (CVR) index showed that the value of CVR in the WM (0.03±0.002%/mm Hg) was positive, but was significantly lower than that in the gray matter (GM) (0.22±0.01%/mm Hg). More strikingly, the WM response showed a temporal delay of 19±3 seconds compared with GM, which was attributed to the longer time it takes for extravascular CO2 to change. With age, WM CVR response becomes greater and faster, which is opposite to the changes seen in the GM. These data suggest that characteristics of WM CVR are different from that of GM and caution should be used when interpreting pathologic WM CVR results.

scholarly journals Assessing Cerebrovascular Reactivity in Carotid Steno-Occlusive Disease Using MRI BOLD and ASL Techniques

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Renata F. Leoni ◽  
Kelley C. Mazzetto-Betti ◽  
Afonso C. Silva ◽  
Antonio C. dos Santos ◽  
Draulio B. de Araujo ◽  
...  
Keyword(s):  
Cerebrovascular Diseases ◽  
Blood Oxygenation ◽  
Occlusive Disease ◽  
Cerebrovascular Reactivity ◽  
Vascular Regulation ◽  
Oxygenation Level ◽  
Biochemical Mechanisms ◽  
Magnetic Resonance Imaging Mri ◽  
Source Of Information ◽  
Reliable Methods

Impaired cerebrovascular reactivity (CVR), a predictive factor of imminent stroke, has been shown to be associated with carotid steno-occlusive disease. Magnetic resonance imaging (MRI) techniques, such as blood oxygenation level-dependent (BOLD) and arterial spin labeling (ASL), have emerged as promising noninvasive tools to evaluate altered CVR with whole-brain coverage, when combined with a vasoactive stimulus, such as respiratory task or injection of acetazolamide. Under normal cerebrovascular conditions, CVR has been shown to be globally and homogenously distributed between hemispheres, but with differences among cerebral regions. Such differences can be explained by anatomical specificities and different biochemical mechanisms responsible for vascular regulation. In patients with carotid steno-occlusive disease, studies have shown that MRI techniques can detect impaired CVR in brain tissue supplied by the affected artery. Moreover, resulting CVR estimations have been well correlated to those obtained with more established techniques, indicating that BOLD and ASL are robust and reliable methods to assess CVR in patients with cerebrovascular diseases. Therefore, the present paper aims to review recent studies which use BOLD and ASL to evaluate CVR, in healthy individuals and in patients with carotid steno-occlusive disease, providing a source of information regarding the obtained results and the methodological difficulties.

scholarly journals Correlated Functional Connectivity and Glucose Metabolism in Brain White Matter Revealed by Simultaneous MRI/PET

2021 ◽  
Author(s):  
Bin Guo ◽  
Fugen Zhou ◽  
Muwei Li ◽  
John C Gore ◽  
Zhaohua Ding
Keyword(s):  
White Matter ◽  
Resting State ◽  
Low Frequency ◽  
Blood Oxygenation ◽  
Vascular Density ◽  
Metabolic Demand ◽  
Spatially Correlated ◽  
Brain White Matter ◽  
Oxygenation Level ◽  
The Relationship

Blood oxygenation level-dependent (BOLD) signals in white matter (WM) have usually been ignored or undetected, consistent with the lower vascular density and metabolic demands in WM than in gray matter (GM). Despite converging evidence demonstrating the reliable detection of BOLD signals in WM evoked by neural stimulation and in a resting state, few studies have examined the relationship between BOLD functional signals and tissue metabolism in WM. By analyzing simultaneous recordings of MRI and PET data, we found that the correlations between low frequency resting state BOLD signals in WM are spatially correlated with local glucose uptake, which also covaried with the amplitude of spontaneous low frequency fluctuations in BOLD signals. These results provide further evidence that BOLD signals in WM reflect variations in metabolic demand associated with neural activity, and suggest they should be incorporated into more complete models of brain function.

scholarly journals Intraoperative BOLD-fMRI Cerebrovascular Reactivity Assessment

2021 ◽  
pp. 139-143
Author(s):  
Giovanni Muscas ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Martina Sebök ◽  
Giuseppe Esposito ◽  
Luca Regli ◽  
...  
Keyword(s):  
Cerebrovascular Diseases ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Hemodynamic State ◽  
Neurosurgical Patients ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Ischemic Cerebrovascular Diseases ◽  
Brain Gliomas ◽  
The Brain

AbstractBlood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) has gained attention in recent years as an effective way to investigate CVR, a measure of the hemodynamic state of the brain, with high spatial and temporal resolution. An association between impaired CVR and diverse pathologies has been observed, especially in ischemic cerebrovascular diseases and brain gliomas. The ability to obtain this information intraoperatively is novel and has not been widely tested. We report our first experience with this intraoperative technique in vascular and oncologic neurosurgical patients, discuss the results of its feasibility, and the possible developments of the intraoperative employment of BOLD-CVR.

An overview of functional magnetic-resonance imaging

1996 ◽  
Vol 54 ◽  
pp. 886-887
Author(s):  
Xiaoping Hu ◽  
Tuong Le ◽  
Seong-Gi Kim ◽  
Kamil Ugurbil
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Blood Oxygenation ◽  
Local Concentration ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Cortical Function ◽  
Oxygenation Level ◽  
Magnetic Resonance Imaging Mri

In the past few years, one of the most significant developments in magnetic resonance imaging (MRI) is the use of MR imaging to non-invasively map human cortical function without the use of exogenous contrast agents . Since its introduction in 1992, functional magnetic resonance imaging (fMRI) has emerged as a powerful tool for studying neuronal function and generated an enormous amount of interest among neuroscientists, NMR scientists, and clinicians. The purpose of this paper is to outline the principle of fMRI and the associated technical issues and illustrate the utility of fMRI with representative applications.The basis of fMRI is the blood oxygenation level dependent (BOLD) contrast which is derived from the fact that deoxyhemoglobin is paramagnetic and changes in the local concentration of deoxyhemoglobin within the brain lead to alterations in the magnetic resonance signal. Neuronal activation within the cerebral cortex causes an increase in blood flow without a commensurate increase in oxygen extraction.

scholarly journals Hemodynamic Response Function in Brain White Matter in a Resting State

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Ting Wang ◽  
D Mitchell Wilkes ◽  
Muwei Li ◽  
Xi Wu ◽  
John C Gore ◽  
...  
Keyword(s):  
White Matter ◽  
Response Function ◽  
Gray Matter ◽  
Resting State ◽  
Hemodynamic Response ◽  
Temporal Variations ◽  
Blood Oxygenation ◽  
Hemodynamic Response Function ◽  
Brain White Matter ◽  
Oxygenation Level

Abstract The hemodynamic response function (HRF) characterizes temporal variations of blood oxygenation level-dependent (BOLD) signals. Although a variety of HRF models have been proposed for gray matter responses to functional demands, few studies have investigated HRF profiles in white matter particularly under resting conditions. In the present work we quantified the nature of the HRFs that are embedded in resting state BOLD signals in white matter, and which modulate the temporal fluctuations of baseline signals. We demonstrate that resting state HRFs in white matter could be derived by referencing to intrinsic avalanches in gray matter activities, and the derived white matter HRFs had reduced peak amplitudes and delayed peak times as compared with those in gray matter. Distributions of the time delays and correlation profiles in white matter depend on gray matter activities as well as white matter tract distributions, indicating that resting state BOLD signals in white matter encode neural activities associated with those of gray matter. This is the first investigation of derivations and characterizations of resting state HRFs in white matter and their relations to gray matter activities. Findings from this work have important implications for analysis of BOLD signals in the brain.

Magnetic Resonance Imaging of The Brain in Patients With Migraine

Cephalalgia ◽  
1991 ◽  
Vol 11 (2) ◽  
pp. 69-74 ◽  
Author(s):  
Hisaka Igarashi ◽  
Fumihiko Sakai ◽  
Shinichi Kan ◽  
Jun Okada ◽  
Yoshiaki Tazaki
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Young Patients ◽  
Proton Density ◽  
Resonance Imaging ◽  
Centrum Semiovale ◽  
Migraine Frequency ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain

Magnetic resonance imaging (MRI) was studied in 91 patients with migraine and in 98 controls. Risk factors known to cause MRI lesions were carefully examined. In 36 patients with migraine (39.6%), small foci of high intensity on T2-weighted and proton-density-weighted images were seen in the white matter. Of patients with migraine who were less than 40 years old and without any risk factor, 29.4% showed lesions on MRI; this was significantly higher than the 11.2% for the group of age-matched controls ( n = 98). The lesions were distributed predominantly in the centrum semiovale and frontal white matter in young patients, but extended to the deeper white matter at the level of basal ganglia in the older age group. The side of the MRI lesions did not always correspond to the side of usual aura or headache. Migraine-related variables such as type of migraine, frequency, duration or intensity of headache or consumption of ergotamine showed no significant correlation with the incidence of MRI abnormalities. Our data indicated that migraine may be associated with early pathologic changes in the brain.

scholarly journals Cerebrovascular reactivity mapping without hypercapnic challenge in patients with carotid artery stenosis

2019 ◽  
Vol 13 (2) ◽  
pp. 62
Author(s):  
Kaio Felippe Secchinato ◽  
Pedro Henrique Rodrigues Da Silva ◽  
Ana Paula Afonso Camargo ◽  
Octávio Marques Pontes-Neto ◽  
Renata Ferranti Leoni
Keyword(s):  
Resting State ◽  
Vascular Reactivity ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Breath Holding ◽  
Metabolic Demand ◽  
Additional Equipment ◽  
Oxygenation Level ◽  
Magnetic Resonance Imaging Mri ◽  
Carbon Dioxide Co2

Vascular reactivity represents the ability of the vascular smooth muscle to dilate or contract in response to changes in metabolic demand or vasoactive stimulus. More specifically, the cerebrovascular reactivity (CVR) has raised interest in several studies that point to its potential to predict stroke risk in patients with cerebrovascular disease. CVR mapping is typically performed using carbon dioxide (CO2) inhalation, breath-holding, or acetazolamide injection as vasoactive challenges, while magnetic resonance imaging (MRI) based on the blood oxygenation level-dependent (BOLD) contrast is acquired. However, such challenges of hypercapnia depend on additional equipment and cooperation of the subjects, limiting their applications, especially in elderly patients. Therefore, the objective of the present study was to map the CVR using resting-state MRI-BOLD, with no hypercapnic challenge, considering the variations in BOLD signal associated with variations in the arterial partial pressure of CO2. The CVR maps obtained with resting data showed a high correlation with those obtained by the conventional experiment with CO2 inhalation (r > 0.70). In addition, the CVR changes observed for the patients were consistent with their clinical reports. These results show that the mapping of CVR obtained with resting-state data may become a useful alternative in the detection of perfusion changes in clinical applications when the hypercapnic challenge is not feasible.

scholarly journals Prevalence of Cerebral Microbleeds in Thai Patients with Ischemic Stroke

2017 ◽  
Vol 08 (02) ◽  
pp. 216-220 ◽  
Author(s):  
Artit Potigumjon ◽  
Arvemas Watcharakorn ◽  
Pornpatr A. Dharmasaroja
Keyword(s):  
Ischemic Stroke ◽  
White Matter ◽  
Magnetic Resonance ◽  
White Matter Lesions ◽  
Cerebral Microbleeds ◽  
National Institutes Of Health ◽  
Asian Origin ◽  
Chinese Study ◽  
Japanese Studies ◽  
Magnetic Resonance Imaging Mri

ABSTRACT Background: With the widespread use of magnetic resonance imaging (MRI), cerebral microbleeds (CMBs) are commonly detected. Ethnicity seems to play a role in the prevalence of CMB, with higher prevalence in participants from Asian origin. The purpose of the study is to look for the prevalence of CMBs and associated factors in Thai patients with ischemic stroke. Methods: Patients with acute ischemic stroke who had MRI and magnetic resonance angiography during January–August 2014 were included in the study. T2*-weighted gradient-recalled echo was used to define CMBs. Baseline characteristics, stroke subtypes, and severity of white matter lesions were compared between patients with and without CMBs. Results: Two hundred patients were included in the study. Mean age of the patients was 61-year-old. Mean National Institutes of Health Stroke Scale was 8. The prevalence of CMBs was 20% (39/200 patients). Hypertension (odds ratio [OR] 3.05, 95% confidence interval [CI] 1.07–8.68, P = 0.037), and moderate-to-severe white matter lesions (Fazekas 2–3, OR 7.61, 95% CI 3.06–18.95, P < 0.001) were related to the presence of CMBs. Conclusions: CMBs were found in 20% of patients with ischemic stroke, which was lower than those reported from Japanese studies but comparable to a Chinese study. CMBs were associated with hypertension and severity of the white matter lesions.

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