A novel perspective to calibrate temporal delays in cerebrovascular reactivity using hypercapnic and hyperoxic respiratory challenges

Champagne, Allen A.; Bhogal, Alex A.; Coverdale, Nicole S.; Mark, Clarisse I.; Cook, Douglas J.

doi:10.1016/j.neuroimage.2017.11.044

Cited by 22 publications

(29 citation statements)

References 49 publications

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“…Similar clustering results were also reported in a recent work by (Champagne et al, 2017). In this work, the authors employed a novel protocol, which involved hyperoxic gas challenges, to obtain step hypercapnia-induced response delay maps calibrated for blood arrival time.…”

Section: The Dcvr Curve Shape and Its Relation To The Underlying Anatomysupporting

confidence: 84%

“…those with an initial undershoot followed by a larger overshoot) possibly reflect a delayed response to CO2 challenges as well. These shapes were mainly associated with cluster 2, which in most subjects overlaps with the voxel clusters with long hypercapnia-induced response delay in (Champagne et al, 2017). However, differentiation of possible causes for the longer temporal delays during CO2 challenges was not feasible using the data analyzed in our work and remains to be studied in future research.…”

Section: The Dcvr Curve Shape and Its Relation To The Underlying Anatomymentioning

confidence: 90%

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Modeling of dynamic cerebrovascular reactivity to spontaneous and externally induced CO2 fluctuations in the human brain using BOLD-fMRI

et al. 2019

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In this work, we investigate the regional characteristics of the dynamic interactions between arterial CO2 and BOLD (dynamic cerebrovascular reactivity-dCVR) during normal breathing and hypercapnic, externally induced step CO2 challenges. To obtain dCVR curves at each voxel, we use a custom set of basis functions based on the Laguerre and gamma basis sets. This allows us to obtain robust dCVR estimates both in larger regions of interest (ROIs), as well as in individual voxels. We also implement classification schemes to identify brain regions with similar dCVR characteristics. Our results reveal considerable variability of dCVR across different brain regions, as well as during different experimental conditions (normal breathing and hypercapnic challenges), suggesting a differential response of cerebral vasculature to spontaneous CO2 fluctuations and larger, externally induced CO2 changes. The clustering results suggest that anatomically distinct brain regions exhibit different dCVR curves that do not exhibit the standard, positive valued curves that have been previously reported. They also revealed a consistent set of dCVR cluster shapes for resting and forcing conditions that exhibited different distribution patterns across brain voxels.

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Section: The Dcvr Curve Shape and Its Relation To The Underlying Anatomysupporting

confidence: 84%

Section: The Dcvr Curve Shape and Its Relation To The Underlying Anatomymentioning

confidence: 90%

Modeling of dynamic cerebrovascular reactivity to spontaneous and externally induced CO2 fluctuations in the human brain using BOLD-fMRI

et al. 2019

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“…For example, during the resting state, signals in WM were shown to have a delayed positive correlation with GM (Erdogan et al, 2016), an observation that has been attributed to a longer vascular transit time in WM (Tong et al, 2017). Delayed effects in WM have also been observed during respiratory CO 2 challenges (Champagne et al, 2017;Thomas et al, 2014). At the same time, WM and GM have also been found to show opposing correlations with a peripherally measured (fingertip) PPG and NIRS signals (van Houdt et al, 2010;Tong et al, 2013), as well as with respiratory challenges (Bright et al, 2014).…”

Section: Introductionmentioning

confidence: 98%

Contribution of systemic vascular effects to fMRI activity in white matter

et al. 2018

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To investigate a potential contribution of systemic physiology to recently reported BOLD fMRI signals in white matter, we compared photo-plethysmography (PPG) and whole-brain fMRI signals recorded simultaneously during long resting-state scans from an overnight sleep study. We found that intermittent drops in the amplitude of the PPG signal exhibited strong and widespread correlations with the fMRI signal, both in white matter (WM) and in gray matter (GM). The WM signal pattern resembled that seen in previous resting-state fMRI studies and closely tracked the location of medullary veins. Its temporal cross-correlation with the PPG amplitude was bipolar, with an early negative value. In GM, the correlation was consistently positive. Consistent with previous studies comparing physiological signals with fMRI, these findings point to a systemic vascular contribution to WM fMRI signals. The PPG drops are interpreted as systemic vasoconstrictive events, possibly related to intermittent increases in sympathetic tone related to fluctuations in arousal state. The counter-intuitive polarity of the WM signal is explained by long blood transit times in the medullary vasculature of WM, which cause blood oxygenation loss and a substantial timing mismatch between blood volume and blood oxygenation effects. A similar mechanism may explain previous findings of negative WM signals around large draining veins during both task- and resting-state fMRI.

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“…reaction time. As BOLD delay time assessment provides us with two important measures of cerebrovascular health, the technique has gained increasing attention ( Christen et al., 2015b ; Cogswell et al., 2017 ; Liu et al., 2017b ; Donahue et al., 2015 ; Champagne et al., 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Effect sizes of BOLD CVR, resting-state signal fluctuations and time delay measures for the assessment of hemodynamic impairment in carotid occlusion patients

et al. 2018

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Background and purposeThe BOLD signal amplitude as a response to a hypercapnia stimulus is commonly used to assess cerebrovascular reserve. Despite recent advances, the implementation remains cumbersome and alternative ways to assess hemodynamic impairment are desirable. Resting-state BOLD signal fluctuations (rsBOLD) have been proposed however data on its sensitivity and dependence on baseline venous cerebral blood volume (vCBV) is limited. The primary aim of this study was to compare the effect sizes of resting-state and hypercapnia induced BOLD signal changes in the detection of hemodynamic impairment. The second aim of the study was to assess the dependence of BOLD signal variability on vCBV.Materials and methodsFifteen patients with internal carotid artery occlusive disease and 15 matched healthy controls were included in this study. The BOLD signal was derived from a dual-echo gradient-echo echo-planar sequence during hypercapnia (HC) and hyperoxia (HO) gas modulations. BOLD (fractional) amplitude of low frequency fluctuations ((f)ALFF) was compared to HC-BOLD, BOLD response delays derived from time delay analysis and ΔBOLD in response to progressively increasing HC. Effect sizes (i.e. the standard mean difference between patients and controls) were calculated. HO-BOLD was used to estimate vCBV, and its contribution to the variability in rsBOLD signal was evaluated.ResultsThe effect sizes of ALFF and fALFF (0.61 and 0.72) were lower than the effect sizes related to hypercapnia-based hemodynamic assessment analysis; 1.62, 1.56 and 0.90 for HC-BOLD, BOLD response delays and ΔBOLD in response to progressively increasing HC. A moderate relation was found between (f)ALFF and HC-BOLD in controls (R2 of 0.61 and 0.42), but this relation decreased in patients (R2 of 0.33 and 0.15). (f)ALFF did not differ between patients and controls whereas HC-BOLD did (p < 0.005). The ΔBOLD response to progressively increasing HC was significantly different in between patients and controls for ΔEtCO2 values ≥ 2 mmHg (at +2 mmHg F(1, 18) = 5.85, p = 0.026). Up to 31% and 53% of the variance in the ALFF and HC-BOLD spatial distribution could be explained by HO-BOLD.ConclusionALFF and fALFF demonstrated a moderate effect size to detect hemodynamic impairment whereas the effect size was large for methods employing a hypercapnia-based vascular stress stimulus. Based on our analysis of BOLD signal change as a response to a progressively increasing hypercapnia stimulus we can argue that a hypercapnia stimulus of at least 2 mmHg above baseline EtCO2 is necessary to evaluate hemodynamic impairment. We also demonstrated that a substantial amount of information imbedded in the rsBOLD and HC-BOLD was explained by HO-BOLD. HO-BOLD can serve as a proxy for vCBV and this thus indicates that one should be careful when adopting these techniques in disease cases with compromised CBV.

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A novel perspective to calibrate temporal delays in cerebrovascular reactivity using hypercapnic and hyperoxic respiratory challenges

Cited by 22 publications

References 49 publications

Modeling of dynamic cerebrovascular reactivity to spontaneous and externally induced CO2 fluctuations in the human brain using BOLD-fMRI

Modeling of dynamic cerebrovascular reactivity to spontaneous and externally induced CO2 fluctuations in the human brain using BOLD-fMRI

Contribution of systemic vascular effects to fMRI activity in white matter

Effect sizes of BOLD CVR, resting-state signal fluctuations and time delay measures for the assessment of hemodynamic impairment in carotid occlusion patients

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