Abstract 2762: Asymmetry of The Blood Oxygen Level-Dependent fMRI Response During Hypercapnia Is Reliable to Evaluate Cerebrovascular Reactivity in Patients with Severe Unilateral Carotid Stenosis

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Kelley C Mazzetto-Betti ◽  
Luis H Castro-Afonso ◽  
Pedro T Pinto ◽  
Antonio C dos Santos ◽  
Daniel Abud ◽  
...  
Keyword(s):  
Carotid Stenosis ◽  
Auditory Stimulus ◽  
Onset Time ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Bold Signal ◽  
Blood Oxygen Level ◽  
Time To Peak ◽  
Width Difference

Background and Purpose: Previous transcranial Doppler studies have suggested that, in patients with severe carotid stenosis, the lack of cerebrovascular reactivity (CVR) is an independent predictor of ipsilateral stroke. The BOLD (Blood Oxygenation Level-Dependent) fMRI contrast can be used to assess the CVR during normal condition and during hemodynamic stress, like hypercapnia. The purpose of this study is to evaluate the BOLD signal parameters on the Middle Cerebral Artery (MCA) territory, induced by auditory stimulus, during different levels of hypercapnia in patients with severe unilateral carotid stenosis, comparing the ipsilateral hemisphere (IH) to the contralateral hemisphere (CH). Methods: The images were obtained from 16 patients with severe unilateral carotid stenosis. Patients were submitted to an auditory stimulus (3s) in three different conditions: normocapnia and at EtCO2 increase of 5 and 10mmHg. The images were acquired with a 3T Philips MR, preprocessed and analyzed using an autoregressive method. Results: The BOLD signal from the IH was different from the CH during the basal condition and at 5mmHg (p<0.0001), but not at the 10mmHg ETCO2 increase. For each BOLD parameter, the major differences between the hemispheres were seen on the onset time (p<0.0001) and amplitude of BOLD signal (p<0.0001). The width difference was significant between the basal and 10mmhHg increase (p<0.01). In these three parameters, the BOLD signal of the IH presented no significant variations with the CO2 increment. However, the BOLD signal for CH showed an increase on the time-to-onset and width and amplitude decrease. The time to peak parameters of the BOLD signal showed no differences between the hemispheres and at hypercapnic conditions. Conclusion: In our results the IH did not respond to the hypercapnic stress as the CH. Therefore, among patients with severe carotid stenosis, BOLD can reliably identify some that have an exhausted CVR, which cannot respond to a vasodilatory stress like hypercapnia. Future studies using this technique may help to select patients for recanalization procedures.

scholarly journals A novel method of quantifying hemodynamic delays to improve hemodynamic response, and CVR estimates in CO2 challenge fMRI

2021 ◽  
pp. 0271678X2097858
Author(s):  
Jinxia (Fiona) Yao ◽  
Ho-Ching (Shawn) Yang ◽  
James H Wang ◽  
Zhenhu Liang ◽  
Thomas M Talavage ◽  
...  
Keyword(s):  
Arrival Time ◽  
Stress Test ◽  
Low Frequency ◽  
Hemodynamic Response ◽  
Blood Oxygen Level Dependent ◽  
Cerebrovascular Reactivity ◽  
Bold Signal ◽  
Hemodynamic Response Function ◽  
Carbon Dioxide Co2 ◽  
Co2 Challenge

Elevated carbon dioxide (CO2) in breathing air is widely used as a vasoactive stimulus to assess cerebrovascular functions under hypercapnia (i.e., “stress test” for the brain). Blood-oxygen-level-dependent (BOLD) is a contrast mechanism used in functional magnetic resonance imaging (fMRI). BOLD is used to study CO2-induced cerebrovascular reactivity (CVR), which is defined as the voxel-wise percentage BOLD signal change per mmHg change in the arterial partial pressure of CO2 (PaCO2). Besides the CVR, two additional important parameters reflecting the cerebrovascular functions are the arrival time of arterial CO2 at each voxel, and the waveform of the local BOLD signal. In this study, we developed a novel analytical method to accurately calculate the arrival time of elevated CO2 at each voxel using the systemic low frequency oscillations (sLFO: 0.01-0.1 Hz) extracted from the CO2 challenge data. In addition, 26 candidate hemodynamic response functions (HRF) were used to quantitatively describe the temporal brain reactions to a CO2 stimulus. We demonstrated that our approach improved the traditional method by allowing us to accurately map three perfusion-related parameters: the relative arrival time of blood, the hemodynamic response function, and CVR during a CO2 challenge.

scholarly journals Brain reactivity using fMRI to insomnia stimuli in insomnia patients with discrepancy between subjective and objective sleep

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Young-Bo Kim ◽  
Nambeom Kim ◽  
Jae Jun Lee ◽  
Seo-Eun Cho ◽  
Kyoung-Sae Na ◽  
...  
Keyword(s):  
Brain Activity ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Cognitive Distortion ◽  
Sleep Diary ◽  
Bold Signal ◽  
Blood Oxygen Level ◽  
General Anxiety ◽  
Sleep Deficit ◽  
Perception Of Sleep

AbstractSubjective–objective discrepancy of sleep (SODS) might be related to the distorted perception of sleep deficit and hypersensitivity to insomnia-related stimuli. We investigated differences in brain activation to insomnia-related stimuli among insomnia patients with SODS (SODS group), insomnia patients without SODS (NOSODS group), and healthy controls (HC). Participants were evaluated for subjective and objective sleep using sleep diary and polysomnography. Functional magnetic resonance imaging was conducted during the presentation of insomnia-related (Ins), general anxiety-inducing (Gen), and neutral (Neu) stimuli. Brain reactivity to the contrast of Ins vs. Neu and Gen vs. Neu was compared among the SODS (n = 13), NOSODS (n = 15), and HC (n = 16) groups. In the SODS group compared to other groups, brain areas including the left fusiform, bilateral precuneus, right superior frontal gyrus, genu of corpus callosum, and bilateral anterior corona radiata showed significantly increased blood oxygen level dependent (BOLD) signal in the contrast of Ins vs. Neu. There was no brain region with significantly increased BOLD signal in the Gen vs. Neu contrast in the group comparisons. Increased brain activity to insomnia-related stimuli in several brain regions of the SODS group is likely due to these individuals being more sensitive to sleep-related threat and negative cognitive distortion toward insomnia.

Blood oxygen-level dependent functional assessment of cerebrovascular reactivity: Feasibility for intraoperative 3 Tesla MRI

2016 ◽  
Vol 77 (2) ◽  
pp. 806-813 ◽  
Author(s):  
Jorn Fierstra ◽  
Jan-Karl Burkhardt ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Marco Piccirelli ◽  
Athina Pangalu ◽  
...  
Keyword(s):  
Functional Assessment ◽  
Blood Oxygen Level Dependent ◽  
Cerebrovascular Reactivity ◽  
3 Tesla ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
3 Tesla Mri

scholarly journals Arterial Spin Labeling and Blood Oxygen Level-Dependent MRI Cerebrovascular Reactivity in Cerebrovascular Disease: A Systematic Review and Meta-Analysis

2016 ◽  
Vol 42 (3-4) ◽  
pp. 288-307 ◽  
Author(s):  
Diederik P.J. Smeeing ◽  
Jeroen Hendrikse ◽  
Esben T. Petersen ◽  
Manus J. Donahue ◽  
Jill B. de Vis
Keyword(s):  
Cerebrovascular Disease ◽  
Arterial Spin Labeling ◽  
Meta Analysis ◽  
Spin Labeling ◽  
Blood Oxygen Level Dependent ◽  
Cerebrovascular Reactivity ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Occlusive Vascular Disease

Background: The cerebrovascular reactivity (CVR) results of blood oxygen level-dependent (BOLD) and arterial spin labeling (ASL) MRI studies performed in patients with cerebrovascular disease (steno-occlusive vascular disease or stroke) were systematically reviewed. Summary: Thirty-one articles were included. Twenty-three (74.2%) studies used BOLD MRI to evaluate the CVR, 4 (12.9%) studies used ASL MRI and 4 (12.9%) studies used both BOLD and ASL MRI. Thirteen studies (3 significant) found a lower BOLD CVR, 2 studies found a similar CVR and 3 studies found a higher CVR in the ipsilateral compared to the contralateral hemisphere. Nine (5 significant) out of 10 studies found a lower BOLD CVR in the ipsilateral hemispheres of patients compared to controls. Six studies (2 significant) found a lower ASL CVR in the ipsilateral compared to the contralateral hemispheres. Three out of 5 studies found a significant lower ASL CVR in the ipsilateral hemispheres of patients compared to controls. Key Messages: This review brings support for a reduced BOLD and ASL CVR in the ipsilateral hemisphere of patients with cerebrovascular disease. We suggest that future studies will be performed in a uniform way so reference values can be established and could be used to guide treatment decisions in patients with cerebrovascular disease.

scholarly journals Functional magnetic resonance imaging evaluation of lumbosacral radiculopathic pain

2016 ◽  
Vol 25 (4) ◽  
pp. 517-522
Author(s):  
Alex J. Koefman ◽  
Melissa Licari ◽  
Michael Bynevelt ◽  
Christopher R. P. Lind
Keyword(s):  
Objective Assessment ◽  
Blood Oxygen Level Dependent ◽  
Bold Signal ◽  
Blood Oxygen Level ◽  
Imaging Evaluation ◽  
Pain Experience ◽  
Lumbosacral Radiculopathy ◽  
Signal Change ◽  
Left Parietal Cortex ◽  
Straight Leg Raise

OBJECTIVE An objective biomarker for pain is yet to be established. Functional MRI (fMRI) is a promising neuroimaging technique that may reveal an objective radiological biomarker. The purpose of this study was to evaluate fMRI technology in the setting of lumbosacral radiculopathy and discuss its application in revealing a biomarker for pain in the future. METHODS A prospective, within-participant control study was conducted. Twenty participants with painful lumbosacral radiculopathy from intervertebral disc pathology were recruited. Functional imaging of the brain was performed during a randomly generated series of nonprovocative and provocative straight leg raise maneuvers. RESULTS With a statistical threshold set at p < 0.000001, 3 areas showed significant blood oxygen level–dependent (BOLD) signal change: right superior frontal gyrus (x = 2, y = 13, z = 48, k = 29, Brodmann area 6 [BA6]), left supramarginal cortex (x = −37, y = −44, z = 33, k = 1084, BA40), and left parietal cortex (x = −19, y = −41, z = 63, k = 354, BA5). With a statistical threshold set at p < 0.0002, 2 structures showed significant BOLD signal change: right putamen (x = 29, y = −11, z = 6, k = 72) and bilateral thalami (right: x = 23, y = −11, z = 21, k = 29; x = 8, y = −11, z = 9, k = 274; and left: x = −28, y = −32, z = 6, k = 21). CONCLUSIONS The results in this study compare with those in previous studies and suggest that fMRI technology can provide an objective assessment of the pain experience.

scholarly journals Distinct neurophysiological correlates of the fMRI BOLD signal in the hippocampus and neocortex

2021 ◽  
Author(s):  
Paul F. Hill ◽  
Sarah E. Seger ◽  
Hye Bin Yoo ◽  
Danielle R. King ◽  
Bradley C. Lega ◽  
...  
Keyword(s):  
Neural Activity ◽  
Blood Oxygen Level Dependent ◽  
Gamma Band ◽  
Bold Signal ◽  
Blood Oxygen Level ◽  
Indirect Measure ◽  
Neural Architecture ◽  
High Gamma ◽  
Gamma Band Activity ◽  
Band Activity

AbstractFunctional magnetic resonance imaging (fMRI) is among the foremost methods for mapping human brain function but provides only an indirect measure of underlying neural activity. Recent findings suggest that the neurophysiological correlates of the fMRI blood-oxygen-level-dependent (BOLD) signal might be regionally specific. We examined the neurophysiological correlates of the fMRI BOLD signal in the hippocampus and neocortex, where differences in neural architecture might result in a different relationship between the respective signals. Fifteen human neurosurgical patients (10 female, 5 male) implanted with depth electrodes performed a verbal free recall task while electrophysiological activity was recorded simultaneously from hippocampal and neocortical sites. The same patients subsequently performed a similar version of the task during a later fMRI session. Subsequent memory effects (SMEs) were computed for both imaging modalities as patterns of encoding-related brain activity predictive of later free recall. Linear mixed-effects modelling revealed that the relationship between BOLD and gamma-band SMEs was moderated by the lobar location of the recording site. BOLD and high gamma (70-150 Hz) SMEs positively covaried across much of the neocortex. This relationship was reversed in the hippocampus, where a negative correlation between BOLD and high gamma SMEs was evident. We also observed a negative relationship between BOLD and low gamma (30-70 Hz) SMEs in the medial temporal lobe more broadly. These results suggest that the neurophysiological correlates of the BOLD signal in the hippocampus differ from those observed in the neocortex.Significance StatementThe blood-oxygen-level-dependent (BOLD) signal forms the basis of fMRI but provides only an indirect measure of neural activity. Task-related modulation of BOLD signals are typically equated with changes in gamma-band activity; however, relevant empirical evidence comes largely from the neocortex. We examined neurophysiological correlates of the BOLD signal in the hippocampus, where the differing neural architecture might result in a different relationship between the respective signals. We identified a positive relationship between encoding-related changes in BOLD and gamma-band activity in frontal, temporal, and parietal cortex. This effect was reversed in the hippocampus, where BOLD and gamma-band effects negatively covaried. These results suggest regional variability in the transfer function between neural activity and the BOLD signal in the hippocampus and neocortex.

scholarly journals Cerebrovascular reactivity assessment with O2-CO2 exchange ratio under brief breath hold challenge

2019 ◽  
Author(s):  
Suk Tak Chan ◽  
Karleyton C. Evans ◽  
Tian Yue Song ◽  
Juliett Selb ◽  
Andre van der Kouwe ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Partial Pressure ◽  
Cerebral Arteries ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Breath Holding ◽  
Breath Hold ◽  
Bold Signal ◽  
Signal Changes

AbstractHypercapnia during breath holding is believed to be the dominant driver behind the modulation of cerebral blood flow (CBF). Here we showed that the cerebrovascular responses to brief breath hold epochs were coupled not only with increased partial pressure of carbon dioxide (PCO2), but also with a decrease in partial pressure of oxygen (PO2). We used transcranial Doppler ultrasound to evaluate the CBF changes during breath holding by measuring the cerebral blood flow velocity (CBFv) in the middle cerebral arteries, a pair of cerebral arteries that supply most parts of the brain. The regional CBF changes during breath hold epochs were mapped with blood oxygenation level dependent (BOLD) signal changes as surrogate of CBF changes using functional magnetic resonance imaging (fMRI) technique. Given the interdependence of the dynamic changes between PCO2 and PO2, we found that the breath-by-breath O2-CO2 exchange ratio (bER), namely the ratio of changes in PO2 (ΔPO2) to changes in PCO2 (ΔPCO2) between end inspiration and end expiration, was superior to either ΔPO2 or ΔPCO2 alone in coupling with the changes of CBFv and BOLD signals under breath hold challenge. The regional cerebrovascular reactivity (CVR) results derived by regressing BOLD signal changes on bER under breath hold challenge resembled those derived by regressing BOLD signal changes on end-tidal partial pressure of CO2 (PETCO2) under exogenous CO2 challenge. Our findings provide a novel insight on the potential of using bER to better quantify CVR changes under breath hold challenge, although the physiological mechanisms of cerebrovascular changes underlying breath hold and exogenous CO2 challenges are potentially different.

scholarly journals Slowed Temporal and Parietal Cerebrovascular Response in Patients with Alzheimer’s Disease

2020 ◽  
Vol 47 (3) ◽  
pp. 366-373
Author(s):  
Kenneth R. Holmes ◽  
David Tang-Wai ◽  
Kevin Sam ◽  
Larissa McKetton ◽  
Julien Poublanc ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Vascular Dysfunction ◽  
Intermediate Stage ◽  
Blood Oxygen Level Dependent ◽  
Cerebrovascular Reactivity ◽  
Blood Oxygen Level ◽  
Cerebrovascular Function ◽  
Anatomical Images ◽  
Cortical Regions

ABSTRACT:Background:Recent investigations now suggest that cerebrovascular reactivity (CVR) is impaired in Alzheimer’s disease (AD) and may underpin part of the disease’s neurovascular component. However, our understanding of the relationship between the magnitude of CVR, the speed of cerebrovascular response, and the progression of AD is still limited. This is especially true in patients with mild cognitive impairment (MCI), which is recognized as an intermediate stage between normal aging and dementia. The purpose of this study was to investigate AD and MCI patients by mapping repeatable and accurate measures of cerebrovascular function, namely the magnitude and speed of cerebrovascular response (τ) to a vasoactive stimulus in key predilection sites for vascular dysfunction in AD.Methods:Thirty-three subjects (age range: 52–83 years, 20 males) were prospectively recruited. CVR and τ were assessed using blood oxygen level-dependent MRI during a standardized carbon dioxide stimulus. Temporal and parietal cortical regions of interest (ROIs) were generated from anatomical images using the FreeSurfer image analysis suite.Results:Of 33 subjects recruited, 3 individuals were excluded, leaving 30 subjects for analysis, consisting of 6 individuals with early AD, 11 individuals with MCI, and 13 older healthy controls (HCs). τ was found to be significantly higher in the AD group compared to the HC group in both the temporal (p = 0.03) and parietal cortex (p = 0.01) following a one-way ANCOVA correcting for age and microangiopathy scoring and a Bonferroni post-hoc correction.Conclusion:The study findings suggest that AD is associated with a slowing of the cerebrovascular response in the temporal and parietal cortices.

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