scholarly journals Global fluctuations of cerebral blood flow indicate a global brain network independent of systemic factors

2017 ◽  
Vol 39 (2) ◽  
pp. 302-312 ◽  
Author(s):  
Li Zhao ◽  
David C Alsop ◽  
John A Detre ◽  
Weiying Dai
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Networks ◽  
Blood Oxygenation ◽  
Regional Network ◽  
Electrical Measurements ◽  
Regional Networks ◽  
Systemic Factors ◽  
Band Limited ◽  
Global Fluctuations

Global synchronization across specialized brain networks is a common feature of network models and in-vivo electrical measurements. Although the imaging of specialized brain networks with blood oxygenation sensitive resting state functional magnetic resonance imaging (rsfMRI) has enabled detailed study of regional networks, the study of globally correlated fluctuations with rsfMRI is confounded by spurious contributions to the global signal from systemic physiologic factors and other noise sources. Here we use an alternative rsfMRI method, arterial spin labeled perfusion MRI, to characterize global correlations and their relationship to correlations and anti-correlations between regional networks. Global fluctuations that cannot be explained by systemic factors dominate the fluctuations in cerebral blood flow. Power spectra of these fluctuations are band limited to below 0.05 Hz, similar to prior measurements of regional network fluctuations in the brain. Removal of these global fluctuations prior to measurement of regional networks reduces all regional network fluctuation amplitudes to below the global fluctuation amplitude and changes the strength and sign of inter network correlations. Our findings support large amplitude, globally synchronized activity across networks that require a reassessment of regional network amplitude and correlation measures.

scholarly journals Acute effect of glucose on cerebral blood flow, blood oxygenation, and oxidative metabolism

2014 ◽  
Vol 36 (2) ◽  
pp. 707-716 ◽  
Author(s):  
Feng Xu ◽  
Peiying Liu ◽  
Juan M Pascual ◽  
Guanghua Xiao ◽  
Hao Huang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Oxidative Metabolism ◽  
Acute Effect ◽  
Blood Oxygenation ◽  
Effect Of Glucose

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 Single-vessel cerebral blood flow fMRI to map blood velocity by phase-contrast imaging

2020 ◽  
Author(s):  
Xuming Chen ◽  
Yuanyuan Jiang ◽  
Sangcheon Choi ◽  
Rolf Pohmann ◽  
Klaus Scheffler ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
High Resolution ◽  
High Field ◽  
Phase Contrast ◽  
Blood Oxygenation ◽  
Contrast Imaging ◽  
Velocity Mapping ◽  
Single Vessel ◽  
Mapping Scheme

AbstractCurrent approaches to high-field fMRI provide two means to map hemodynamics at the level of single vessels in the brain. One is through changes in deoxyhemoglobin in venules, i.e., blood oxygenation level-dependent (BOLD) fMRI, while the second is through changes in arteriole diameter, i.e., cerebral blood volume (CBV) fMRI. Here we introduce cerebral blood flow (CBF)-fMRI, which uses high-resolution phase-contrast MRI to form velocity measurements of flow and demonstrate CBF-fMRI in single penetrating microvessels across rat parietal cortex. In contrast to the venule-dominated BOLD and arteriole-dominated CBV fMRI signal, the phase-contrast -based CBF signal changes are highly comparable from both arterioles and venules. Thus, we have developed a single-vessel fMRI platform to map the BOLD, CBV, and CBF from penetrating microvessels throughout the cortex. This high-resolution single-vessel fMRI mapping scheme not only enables the vessel-specific hemodynamic mapping in diseased animal models but also presents a translational potential to map vascular dementia in diseased or injured human brains with ultra-high field fMRI.SummaryWe established a high-resolution PC-based single-vessel velocity mapping method using the high field MRI. This PC-based micro-vessel velocity measurement enables the development of the single-vessel CBF-fMRI method. In particular, in contrast to the arteriole-dominated CBV and venule-dominated BOLD responses, the CBF-fMRI shows similar velocity changes in penetrating arterioles and venules in activated brain regions. Thus, we have built a noninvasive single-vessel fMRI mapping scheme for BOLD, CBV, and CBF hemodynamic parameter measurements in animals.

The Effect of Esmolol on Cerebral Blood Flow, Cerebral Vasoreactivity, and Cognitive Performance: A Functional Magnetic Resonance Imaging Study

2005 ◽  
Vol 102 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Wolfgang Heinke ◽  
Stefan Zysset ◽  
Margret Hund-Georgiadis ◽  
Derk Olthoff ◽  
D Yves von Cramon
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Magnetic Resonance Imaging ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Background Esmolol is often applied perioperatively to maintain stable hemodynamic conditions in neurosurgical patients. Little is known, however, about its effects on cerebral circulation. The authors employed functional magnetic resonance imaging based on blood oxygenation level-dependent contrast to explore the effect of esmolol on the human brain. The purpose of the study was to investigate the effect of esmolol on cerebral blood flow, cerebral vasoreactivity, and cognitive performance. Methods Ten healthy volunteers were investigated in two separate experimental sessions using functional magnetic resonance imaging. During the first experimental session, a hyperventilation task and a cognitive task, subjects had to perform both tasks twice, once after administration of an esmolol bolus of 1 mg/kg followed by a continuous infusion of 150 microg.kg.min and once without beta-blockade, in a random order. During the second experimental session subjects were scanned at resting state after administration of esmolol. Furthermore, the effect of the esmolol dose on hemodynamic changes caused by beta-adrenergic stimulation with orciprenaline was investigated. Results Esmolol decreased heart rate and blood pressure during the various experimental conditions and blunted the increase in heart rate and blood pressure caused by orciprenaline. Infusion of esmolol affects neither the blood oxygenation level-dependent contrast during the functional challenges nor the reaction times during the cognitive task. However, the esmolol bolus caused a brief blood oxygenation level-dependent contrast increase. Conclusion The results indicate that effective beta-blockade with esmolol does not affect cerebral blood flow, cerebrovascular reactivity, or cognitive performance.

scholarly journals Cerebral blood flow modulation insufficiency in brain networks in multiple sclerosis: A hypercapnia MRI study

2016 ◽  
Vol 36 (12) ◽  
pp. 2087-2095 ◽  
Author(s):  
Olga Marshall ◽  
Sanjeev Chawla ◽  
Hanzhang Lu ◽  
Louise Pape ◽  
Yulin Ge
Keyword(s):  
Multiple Sclerosis ◽  
Carbon Dioxide ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Networks ◽  
Cerebrovascular Reactivity ◽  
Functional Networks ◽  
Attention Networks ◽  
Default Mode ◽  
Multiple Sclerosis Patients

Cerebrovascular reactivity measures vascular regulation of cerebral blood flow and is responsible for maintaining healthy neurovascular coupling. Multiple sclerosis exhibits progressive neurodegeneration and global cerebrovascular reactivity deficits. This study investigates varied degrees of cerebrovascular reactivity impairment in different brain networks, which may be an underlying cause for functional changes in the brain, affecting long-distance projection integrity and cognitive function; 28 multiple sclerosis and 28 control subjects underwent pseudocontinuous arterial spin labeling perfusion MRI to measure cerebral blood flow under normocapnia (room air) and hypercapnia (5% carbon dioxide gas mixture) breathing. Cerebrovascular reactivity, measured as normocapnic to hypercapnic cerebral blood flow percent increase normalized by end-tidal carbon dioxide change, was determined from seven functional networks (default mode, frontoparietal, somatomotor, visual, limbic, dorsal, and ventral attention networks). Group analysis showed significantly decreased cerebrovascular reactivity in patients compared to controls within the default mode, frontoparietal, somatomotor, and ventral attention networks after multiple comparison correction. Regression analysis showed a significant correlation of cerebrovascular reactivity with lesion load in the default mode and ventral attention networks and with gray matter atrophy in the default mode network. Functional networks in multiple sclerosis patients exhibit varied amounts of cerebrovascular reactivity deficits. Such blood flow regulation abnormalities may contribute to functional communication disruption in multiple sclerosis.

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