Noninvasive diffuse optical monitoring of cerebral blood flow and oxygenation responses to intermittent hypoxia in neonatal rats

Pegah Safavi; Mehrana Mohtasebi; Chowdhury Azimul Haque; Faezeh Akbari; Xuhui Liu; Yiqi Yuan; Li Chen; Lei Chen; Guoqiang Yu

doi:10.1117/1.JBO.31.4.047001

Noninvasive diffuse optical monitoring of cerebral blood flow and oxygenation responses to intermittent hypoxia in neonatal rats

Pegah Safavi
, Mehrana Mohtasebi
, Chowdhury Azimul Haque
, Faezeh Akbari
, Xuhui Liu
, Yiqi Yuan
, Li Chen
, Lei Chen
, Guoqiang Yu

Research output: Contribution to journal › Article › peer-review

Abstract

Significance: Intermittent hypoxia (IH) is common in preterm neonates and can cause hypoxic–ischemic brain injury. Simultaneous monitoring of cerebral blood flow (CBF) and oxygenation is essential to detect oxygen delivery-extraction mismatches and guide intervention. Aim: We aimed to adapt and test an innovative diffuse speckle contrast flow oximetry (DSCFO) system for continuous monitoring of cerebral hemodynamics during IH in neonatal rats, a model approximating human neonates. Approach: Two compact laser diodes and a miniature CMOS camera were integrated into a fiber-free probe for continuous monitoring of changes in relative CBF (rCBF) and oxy- and deoxy-hemoglobin concentrations (Δ[HbO₂] and Δ[Hb]) in 8-day-old neonatal rats. Sham rats (n=6) underwent 10 min of normoxia, whereas IH rats (n=8) experienced 10 cycles of sequential 2-min hypoxia (8% O₂) and 2-min hyperoxia (100% O₂). Results: Sham rats maintained stable cerebral hemodynamics under normoxia, whereas IH rats exhibited pronounced periodic fluctuations during IH. Hypoxic episodes caused instantaneous decreases in rCBF and Δ[HbO₂] and increases in Δ[Hb], whereas hyperoxic episodes reversed these effects, reducing hypoxic stress. However, the pronounced cerebral hemodynamic fluctuations during IH may still contribute to brain injury. Conclusions: We demonstrate an affordable, noninvasive, wearable, fiber-free DSCFO system for continuous monitoring of rCBF, Δ[HbO₂], and Δ[Hb] during IH in neonatal rats. The system captured hypoxia-induced cerebral deoxygenation and hyperoxia-driven recovery, revealing episode-dependent protective and disruptive mechanisms. Future work will correlate DSCFO findings with neurological and histological outcomes to guide IH interventions in large neonatal animal models and human infants.

Original language	English
Article number	047001
Journal	Journal of Biomedical Optics
Volume	31
Issue number	4
DOIs	https://doi.org/10.1117/1.JBO.31.4.047001
State	Published - Apr 1 2026

Bibliographical note

Publisher Copyright:
© The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Funding

We acknowledge financial support from the National Institutes of Health (NIH) (Grant Nos. R01 EB028792, R01-HD101508, R41-NS122722, and R42-MH135825) (G.Y.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Funders	Funder number
National Institutes of Health (NIH)	R01 EB028792, R01-HD101508, R42-MH135825, R41-NS122722

Keywords

brain injury
cerebral blood flow
cerebral blood oxygenation
diffuse laser speckle contrast
intermittent hypoxia
preterm infant

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Biomaterials
Atomic and Molecular Physics, and Optics
Biomedical Engineering

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10.1117/1.JBO.31.4.047001

Cite this

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title = "Noninvasive diffuse optical monitoring of cerebral blood flow and oxygenation responses to intermittent hypoxia in neonatal rats",

abstract = "Significance: Intermittent hypoxia (IH) is common in preterm neonates and can cause hypoxic–ischemic brain injury. Simultaneous monitoring of cerebral blood flow (CBF) and oxygenation is essential to detect oxygen delivery-extraction mismatches and guide intervention. Aim: We aimed to adapt and test an innovative diffuse speckle contrast flow oximetry (DSCFO) system for continuous monitoring of cerebral hemodynamics during IH in neonatal rats, a model approximating human neonates. Approach: Two compact laser diodes and a miniature CMOS camera were integrated into a fiber-free probe for continuous monitoring of changes in relative CBF (rCBF) and oxy- and deoxy-hemoglobin concentrations (Δ[HbO2] and Δ[Hb]) in 8-day-old neonatal rats. Sham rats (n=6) underwent 10 min of normoxia, whereas IH rats (n=8) experienced 10 cycles of sequential 2-min hypoxia (8\% O2) and 2-min hyperoxia (100\% O2). Results: Sham rats maintained stable cerebral hemodynamics under normoxia, whereas IH rats exhibited pronounced periodic fluctuations during IH. Hypoxic episodes caused instantaneous decreases in rCBF and Δ[HbO2] and increases in Δ[Hb], whereas hyperoxic episodes reversed these effects, reducing hypoxic stress. However, the pronounced cerebral hemodynamic fluctuations during IH may still contribute to brain injury. Conclusions: We demonstrate an affordable, noninvasive, wearable, fiber-free DSCFO system for continuous monitoring of rCBF, Δ[HbO2], and Δ[Hb] during IH in neonatal rats. The system captured hypoxia-induced cerebral deoxygenation and hyperoxia-driven recovery, revealing episode-dependent protective and disruptive mechanisms. Future work will correlate DSCFO findings with neurological and histological outcomes to guide IH interventions in large neonatal animal models and human infants.",

keywords = "brain injury, cerebral blood flow, cerebral blood oxygenation, diffuse laser speckle contrast, intermittent hypoxia, preterm infant",

author = "Pegah Safavi and Mehrana Mohtasebi and \{Azimul Haque\}, Chowdhury and Faezeh Akbari and Xuhui Liu and Yiqi Yuan and Li Chen and Lei Chen and Guoqiang Yu",

note = "Publisher Copyright: {\textcopyright} The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.",

year = "2026",

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T1 - Noninvasive diffuse optical monitoring of cerebral blood flow and oxygenation responses to intermittent hypoxia in neonatal rats

AU - Safavi, Pegah

AU - Mohtasebi, Mehrana

AU - Azimul Haque, Chowdhury

AU - Akbari, Faezeh

AU - Liu, Xuhui

AU - Yuan, Yiqi

AU - Chen, Li

AU - Chen, Lei

AU - Yu, Guoqiang

N1 - Publisher Copyright: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

PY - 2026/4/1

Y1 - 2026/4/1

N2 - Significance: Intermittent hypoxia (IH) is common in preterm neonates and can cause hypoxic–ischemic brain injury. Simultaneous monitoring of cerebral blood flow (CBF) and oxygenation is essential to detect oxygen delivery-extraction mismatches and guide intervention. Aim: We aimed to adapt and test an innovative diffuse speckle contrast flow oximetry (DSCFO) system for continuous monitoring of cerebral hemodynamics during IH in neonatal rats, a model approximating human neonates. Approach: Two compact laser diodes and a miniature CMOS camera were integrated into a fiber-free probe for continuous monitoring of changes in relative CBF (rCBF) and oxy- and deoxy-hemoglobin concentrations (Δ[HbO2] and Δ[Hb]) in 8-day-old neonatal rats. Sham rats (n=6) underwent 10 min of normoxia, whereas IH rats (n=8) experienced 10 cycles of sequential 2-min hypoxia (8% O2) and 2-min hyperoxia (100% O2). Results: Sham rats maintained stable cerebral hemodynamics under normoxia, whereas IH rats exhibited pronounced periodic fluctuations during IH. Hypoxic episodes caused instantaneous decreases in rCBF and Δ[HbO2] and increases in Δ[Hb], whereas hyperoxic episodes reversed these effects, reducing hypoxic stress. However, the pronounced cerebral hemodynamic fluctuations during IH may still contribute to brain injury. Conclusions: We demonstrate an affordable, noninvasive, wearable, fiber-free DSCFO system for continuous monitoring of rCBF, Δ[HbO2], and Δ[Hb] during IH in neonatal rats. The system captured hypoxia-induced cerebral deoxygenation and hyperoxia-driven recovery, revealing episode-dependent protective and disruptive mechanisms. Future work will correlate DSCFO findings with neurological and histological outcomes to guide IH interventions in large neonatal animal models and human infants.

AB - Significance: Intermittent hypoxia (IH) is common in preterm neonates and can cause hypoxic–ischemic brain injury. Simultaneous monitoring of cerebral blood flow (CBF) and oxygenation is essential to detect oxygen delivery-extraction mismatches and guide intervention. Aim: We aimed to adapt and test an innovative diffuse speckle contrast flow oximetry (DSCFO) system for continuous monitoring of cerebral hemodynamics during IH in neonatal rats, a model approximating human neonates. Approach: Two compact laser diodes and a miniature CMOS camera were integrated into a fiber-free probe for continuous monitoring of changes in relative CBF (rCBF) and oxy- and deoxy-hemoglobin concentrations (Δ[HbO2] and Δ[Hb]) in 8-day-old neonatal rats. Sham rats (n=6) underwent 10 min of normoxia, whereas IH rats (n=8) experienced 10 cycles of sequential 2-min hypoxia (8% O2) and 2-min hyperoxia (100% O2). Results: Sham rats maintained stable cerebral hemodynamics under normoxia, whereas IH rats exhibited pronounced periodic fluctuations during IH. Hypoxic episodes caused instantaneous decreases in rCBF and Δ[HbO2] and increases in Δ[Hb], whereas hyperoxic episodes reversed these effects, reducing hypoxic stress. However, the pronounced cerebral hemodynamic fluctuations during IH may still contribute to brain injury. Conclusions: We demonstrate an affordable, noninvasive, wearable, fiber-free DSCFO system for continuous monitoring of rCBF, Δ[HbO2], and Δ[Hb] during IH in neonatal rats. The system captured hypoxia-induced cerebral deoxygenation and hyperoxia-driven recovery, revealing episode-dependent protective and disruptive mechanisms. Future work will correlate DSCFO findings with neurological and histological outcomes to guide IH interventions in large neonatal animal models and human infants.

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KW - cerebral blood flow

KW - cerebral blood oxygenation

KW - diffuse laser speckle contrast

KW - intermittent hypoxia

KW - preterm infant

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Noninvasive diffuse optical monitoring of cerebral blood flow and oxygenation responses to intermittent hypoxia in neonatal rats

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

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