Modeling the dynamics of cerebrovascular reactivity to carbon dioxide in fMRI under task and resting-state conditions

Shams, Seyedmohammad; Prokopiou, Prokopis C.; Esmaelbeigi, Azin; Mitsis, Georgios D.; Chen, Jean

doi:10.1016/j.neuroimage.2022.119758

Cited by 2 publications

(2 citation statements)

References 67 publications

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“…The former reflects both systemic blood-flow velocity and transit through the main cerebrovascular arteries, while the latter reflects localized vascular elasticity. It is unfortunately not possible to separate these two quantities unless a deconvolution is performed, presenting its own technical challenges [Atwi et al, 2019;Shams et al, 2022]. The chief alternative reference signal, in the absence of the respiration belt recordings, is the whole-grey-matter BOLD signal [Zvolanek et al, 2023], especially as the global BOLD signal variations during a BH task is largely driven by breathing.…”

Section: Estimation and Interpretation Of Cvr Delaymentioning

confidence: 99%

Robust estimation of dynamic cerebrovascular reactivity using breath-holding fMRI: application in diabetes and hypertension

Nanayakkara

Meusel

Anderson

et al. 2023

Preprint

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Breath-holding (BH) tasks during functional magnetic resonance imaging (fMRI) acquisitions are gaining popularity for non-invasive mapping of carbon-dioxide (CO2) driven cerebrovascular reactivity (CVR), which is a valuable clinical marker of vascular function. However, compliance to BH tasks is often unclear, and the ability to record end-tidal CO2often limited, rendering the optimal analysis of BH fMRI data a challenge. In this work, we demonstrate an adaptive data-driven approach for estimating CVR from BH fMRI data that minimizes errors due to subject non-compliance and regional CVR time delay variability. Building on previous work, we propose a frequency-domain-based approach for CVR estimation without the need for end-tidal CO2(PETCO2) recordings. CVR amplitude is estimated in units of %ΔBOLD directly from the data-driven BH frequency. Serious deviations from the designed task paradigm were suppressed and thus did not bias the estimated CVR values. We demonstrate our method in detecting regional CVR amplitude and time-lag differences in a group of 56 individuals, consisting of healthy (CTL), hypertensive (HT) and diabetic-hypertensive (DM+HT) groups of similar ages and sex ratios. The CVR amplitude was lowest in HT+DM, and HT had a lower CVR amplitude than CTL regionally but the voxelwise comparison did not yield statistical significance. Notably, we demonstrate that the voxelwise CVR time delay estimated in Fourier domain is a more sensitive marker of vascular dysfunction than CVR amplitude. While HT+DM seems to confer longer CVR delays, HT seems to confer shorter delays than CTL. These are the first MRI-based observations of CVR time delay differences between diabetic-hypertensive patients and healthy controls. These results demonstrate the feasibility of extracting CVR amplitude and CVR time delay using BH challenges without PETCO2recordings, and the unique clinical value of CVR time-delay information.

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Section: Estimation and Interpretation Of Cvr Delaymentioning

confidence: 99%

Robust estimation of dynamic cerebrovascular reactivity using breath-holding fMRI: application in diabetes and hypertension

Nanayakkara

Meusel

Anderson

et al. 2023

Preprint

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“…To quantify the mediating mechanism of the HRV and RVT on BOLD signal dynamics, the cardiac response function (CRF) and respiratory response function (RRF). For each subject, the mean signal from each neurofluid ROI as well a the GGMS and CSF velocity time series were deconvolved by the corresponding HRV and RVT using the Laguerre expansion (Prokopiou et al, 2018; Shams et al, 2022) for all macrovascular and CSF ROIs as well as GGMS listed above across three capnias.…”

Section: Methodsmentioning

confidence: 99%

The influence of basal CO₂on neurofluid dynamics measured using resting-state BOLD fMRI

Zhong,

Chang,

Chen

2024

Preprint

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An understanding of neurofluid dynamics has been gaining importance, in part given the link between neurofluid dynamics and glymphatic flow. As carbon dioxide (CO2) strongly modulates cerebral blood volume (CBV) and cerebrospinal fluid (CSF) flow, modulation of basal CO2 through different capnic conditions may offer insight into the mechanisms through which neurofluid dynamics are influenced. In this work, we report observations of neurofluid dynamics at normocapnia as well as during short-term hyper- and hypocapnia. We use the resting-state BOLD fMRI signal in neurofluid regions of interest (i.e. blood vessels, CSF compartments) as a surrogate of neurofluid dynamics. From these BOLD signals, we extract the power and central frequency of signal oscillations. We found that 1) Relative to a normocapnic steady state, both hypocapnic and hypercapnic steady states are associated with increased BOLD signal power and shifts in BOLD signal frequency in vascular ROIs in a band-dependent manner; 2) Relative to hypocapnia, hypercapnia is associated with both increased and decreased BOLD signal power in vascular ROIs, depending on the frequency band; 3) these trends are largely reproduced in the CSF ROIs and in the CSF velocity dynamics; 4) these power and frequency variations across capnic conditions are mostly driven by respiratory and heart-rate differences rather than by steady-state CO2and associated vascular-tone variations; 5) the cardiac and respiratory response functions differ substantially across capnic conditions. This work contributes to the establishment of the BOLD signal as a surrogate for neurofluid flow, and highlight the role of the autonomic nervous system (ANS) in linking vascular and CSF dynamics in the brain. The findings suggest that the ANS is also instrumental in the regulation of neurofluid flow in response to alterations of cerebral hemodynamic homeostasis. Furthermore, our findings suggest that this mechanism of ANS regulation differs across capnic states, or more broadly, across individuals with different basal capnic states.

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Modeling the dynamics of cerebrovascular reactivity to carbon dioxide in fMRI under task and resting-state conditions

Cited by 2 publications

References 67 publications

Robust estimation of dynamic cerebrovascular reactivity using breath-holding fMRI: application in diabetes and hypertension

Robust estimation of dynamic cerebrovascular reactivity using breath-holding fMRI: application in diabetes and hypertension

The influence of basal CO₂on neurofluid dynamics measured using resting-state BOLD fMRI

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Modeling the dynamics of cerebrovascular reactivity to carbon dioxide in fMRI under task and resting-state conditions

Cited by 2 publications

References 67 publications

Robust estimation of dynamic cerebrovascular reactivity using breath-holding fMRI: application in diabetes and hypertension

Robust estimation of dynamic cerebrovascular reactivity using breath-holding fMRI: application in diabetes and hypertension

The influence of basal CO2on neurofluid dynamics measured using resting-state BOLD fMRI

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The influence of basal CO₂on neurofluid dynamics measured using resting-state BOLD fMRI