Breath holding for 20 s following extended expiration is a practical, effective and robust standard when measuring cerebrovascular reactivity in healthy adults using BOLD fMRI at 3 T

Larsen, Jörg; Kallenberg, Kai; Rühlmann, Johanna; Baudewig, Jürgen; Nickel, E.; Knauth, Michael; Dechent, Peter

doi:10.1016/j.ynirp.2021.100021

Cited by 3 publications

(3 citation statements)

References 27 publications

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“…A series of repeated brief breath holds caused an increase in blood pressure 52 , 53 and a hypercapnic state 54 , 55 . As shown in Fig.…”

Section: Resultsmentioning

confidence: 90%

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Enhancing diffuse correlation spectroscopy pulsatile cerebral blood flow signal with near-infrared spectroscopy photoplethysmography

Wu,

Martin,

Renna

et al. 2023

Neurophoton.

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Combining near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) allows for quantifying cerebral blood volume, flow, and oxygenation changes continuously and non-invasively. As recently shown, the DCS pulsatile cerebral blood flow index (pCBF i ) can be used to quantify critical closing pressure (CrCP) and cerebrovascular resistance (CVR i ).Aim: Although current DCS technology allows for reliable monitoring of the slow hemodynamic changes, resolving pulsatile blood flow at large source-detector separations, which is needed to ensure cerebral sensitivity, is challenging because of its low signal-to-noise ratio (SNR). Cardiac-gated averaging of several arterial pulse cycles is required to obtain a meaningful waveform.Approach: Taking advantage of the high SNR of NIRS, we demonstrate a method that uses the NIRS photoplethysmography (NIRS-PPG) pulsatile signal to model DCS pCBF i , reducing the coefficient of variation of the recovered pulsatile waveform (pCBF i-fit ) and allowing for an unprecedented temporal resolution (266 Hz) at a large source-detector separation (>3 cm).Results: In 10 healthy subjects, we verified the quality of the NIRS-PPG pCBF i-fit during common tasks, showing high fidelity against pCBF i (R 2 0.98 AE 0.01). We recovered CrCP and CVR i at 0.25 Hz, >10 times faster than previously achieved with DCS.Conclusions: NIRS-PPG improves DCS pCBF i SNR, reducing the number of gate-averaged heartbeats required to recover CrCP and CVR i .

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“…A series of repeated brief breath holds caused an increase in blood pressure 52 , 53 and a hypercapnic state 54 , 55 . As shown in Fig.…”

Section: Resultsmentioning

confidence: 90%

“…A series of repeated brief breath holds caused an increase in blood pressure 52,53 and a hypercapnic state. 54,55 As shown in Fig. 5(b), the average response to a 20s BH task show increases in HbT (0.4 AE 0.8 μM), SO 2 (0.5% AE 0.8%), CBF i (14% AE 11%), and scalp BF i (23% AE 28%).…”

Section: Breath-holdingmentioning

confidence: 84%

Enhancing diffuse correlation spectroscopy pulsatile cerebral blood flow signal with near-infrared spectroscopy photoplethysmography

Wu,

Martin,

Renna

et al. 2023

Neurophoton.

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show abstract

“…In response to an end expiratory breath hold, typical physiological responses include an increase in blood pressure 57 , 58 and a hypercapnic state 64 , 65 . In Fig.…”

Section: Resultsmentioning

confidence: 99%

Portable, high speed blood flow measurements enabled by long wavelength, interferometric diffuse correlation spectroscopy (LW-iDCS)

Robinson

Renna

Ozana

et al. 2023

Sci Rep

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Diffuse correlation spectroscopy (DCS) is an optical technique that can be used to characterize blood flow in tissue. The measurement of cerebral hemodynamics has arisen as a promising use case for DCS, though traditional implementations of DCS exhibit suboptimal signal-to-noise ratio (SNR) and cerebral sensitivity to make robust measurements of cerebral blood flow in adults. In this work, we present long wavelength, interferometric DCS (LW-iDCS), which combines the use of a longer illumination wavelength (1064 nm), multi-speckle, and interferometric detection, to improve both cerebral sensitivity and SNR. Through direct comparison with long wavelength DCS based on superconducting nanowire single photon detectors, we demonstrate an approximate 5× improvement in SNR over a single channel of LW-DCS in the measured blood flow signals in human subjects. We show equivalence of extracted blood flow between LW-DCS and LW-iDCS, and demonstrate the feasibility of LW-iDCS measured at 100 Hz at a source-detector separation of 3.5 cm. This improvement in performance has the potential to enable robust measurement of cerebral hemodynamics and unlock novel use cases for diffuse correlation spectroscopy.

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Using respiratory challenges to modulate CSF movement across different physiological pathways: An fMRI study

Nair,

Diorio,

Wen

et al. 2024

Imaging Neuroscience

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With growing evidence signifying the impact of cerebrospinal fluid (CSF) flow in facilitating waste clearance from the brain and potential pathophysiological links to neurodegenerative disorders, it is of vital importance to develop effective methods to modulate CSF flow in the brain. Here, we attempt this by means of simple commonly used respiratory challenges—paced breathing and breath holding. Functional Magnetic Resonance Imaging scans of the brain and neck respectively were used to record the craniad and caudad CSF movements at the fourth ventricle from eight healthy volunteers during paced breathing and breath holding. Further, we utilized a novel approach for the first time to combine these separately acquired unidirectional CSF movement signals to compare the CSF flow in both directions (in the fourth ventricle) with the respiratory stimuli as a physiological control. Our results demonstrate that these respiratory challenges enhance the magnitude as well as control the direction of CSF movement in the fourth ventricle. They also reveal the capability of blood CO2 concentration changes (induced by respiratory challenges) in the low-frequency range to bring about these CSF movement modulations. Finally, we also successfully report our novel approach where we use these breathing challenges as a unique control condition to detect the small net CSF flows from independently captured unidirectional signals.

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Breath holding for 20 s following extended expiration is a practical, effective and robust standard when measuring cerebrovascular reactivity in healthy adults using BOLD fMRI at 3 T

Cited by 3 publications

References 27 publications

Enhancing diffuse correlation spectroscopy pulsatile cerebral blood flow signal with near-infrared spectroscopy photoplethysmography

Enhancing diffuse correlation spectroscopy pulsatile cerebral blood flow signal with near-infrared spectroscopy photoplethysmography

Portable, high speed blood flow measurements enabled by long wavelength, interferometric diffuse correlation spectroscopy (LW-iDCS)

Using respiratory challenges to modulate CSF movement across different physiological pathways: An fMRI study

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