Light-scattering signal may indicate critical time zone to rescue brain tissue after hypoxia

Kawauchi, Satoko; Sato, Shunichi; Uozumi, Yoichi; Nawashiro, Hiroshi; Ishihara, Miya; Kikuchi, Makoto

doi:10.1117/1.3542046

Cited by 19 publications

(36 citation statements)

References 19 publications

(33 reference statements)

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“…By fiber-based NIR diffuse-reflectance measurements, we previously observed a unique triphasic reflectance change (TRC) at a certain time after ischemia 10 or hypoxia 11 in rat brains. In that experiment, a pair of optical fibers was placed at the center of the right hemisphere; a few minutes after starting ischemia or hypoxia, diffuse-reflectance intensity at around 805 nm increased, decreased, and increased again; thereafter it remained at a high level by the end of the measurement.…”

Section: Introductionmentioning

confidence: 99%

“…These observations indicate that the period of TRC can be regarded as a critical time zone for cerebral resuscitation. 11 However, since AD is known to be initiated focally and to expand anisotropically in the cortex, [13][14][15] we thought that spatiotemporal behaviors of the diffuse-reflectance change during TRC are important to fully understand the correlation between diffuse-reflectance change and brain tissue reversibility. In the present study, we performed NIR diffuse-reflectance imaging of the rat brain during hypoxia by using a charge-coupled-device (CCD) and examined the relationship between spatiotemporal characteristics of the diffuse-reflectance change and brain tissue reversibility.…”

Section: Introductionmentioning

confidence: 99%

“…In that experiment, a pair of optical fibers was placed at the center of the right hemisphere; a few minutes after starting ischemia or hypoxia, diffuse-reflectance intensity at around 805 nm increased, decreased, and increased again; thereafter it remained at a high level by the end of the measurement. 10,11 The TRC was shown to be associated with anoxic depolarization (AD); cerebral adenosine triphosphate (ATP) in the rats was exhausted during TRC. 12 Hypoxia-reoxygenation experiments under spontaneous respiration showed that when reoxygenation was started before TRC, all rats survived, whereas no rats survived when reoxygenation was started after TRC.…”

Section: Introductionmentioning

confidence: 99%

“…We previously attributed the abovementioned NIR triphasic reflectance change to the changes in light scattering based on wavelength dependence analysis of diffuse-reflectance changes (500 to 900 nm), but we did not perform quantitative estimation of the optical properties. 11 Thus, in the present study, we analyzed diffuse-reflectance changes, which were measured with the same fiber setup as that used previously, to quantify time-dependent changes in the absorption and reduced scattering coefficients, for which we used multiple regression analysis aided by Monte Carlo simulation (MCS). Before analyzing in vivo data, we validated the method based on phantom study.…”

Section: Introductionmentioning

confidence: 99%

“…12 Hypoxia-reoxygenation experiments under spontaneous respiration showed that when reoxygenation was started before TRC, all rats survived, whereas no rats survived when reoxygenation was started after TRC. 11 Survival was probabilistic when reoxygenation was started during TRC. These observations indicate that the period of TRC can be regarded as a critical time zone for cerebral resuscitation.…”

Section: Introductionmentioning

confidence: 99%

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Diffuse light reflectance signals as potential indicators of loss of viability in brain tissue due to hypoxia: charge-coupled-device-based imaging and fiber-based measurement

et al. 2013

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Abstract. Brain tissue is highly vulnerable to ischemia/hypoxia, and real-time monitoring of its viability is important. By fiber-based measurements for rat brain, we previously observed a unique triphasic reflectance change (TRC) after a certain period of time after hypoxia. After TRC, rats could not be rescued, suggesting that TRC can be used as an indicator of loss of brain tissue viability. In this study, we investigated this diffuse-reflectance change due to hypoxia in three parts. First, we developed and validated a theoretical method to quantify changes in the absorption and reduced scattering coefficients involved in TRC. Second, we performed charge-coupled-device-based reflectance imaging of the rat brain during hypoxia followed by reoxygenation to examine spatiotemporal characteristics of the reflectance and its correlation with reversibility of brain tissue damage. Third, we made simultaneous imaging and fiber-based measurement of the reflectance for the rat to compare signals obtained by these two modalities. We observed a nontriphasic reflectance change by the imaging, and it was associated with brain tissue viability. We found that TRC measured by the fibers preceded the reflectance-signal change captured by the imaging. This time difference is attributable to the different observation depths in the brain with these two methods. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diffuse light reflectance signals as potential indicators of loss of viability in brain tissue due to hypoxia: charge-coupled-device-based imaging and fiber-based measurement

et al. 2013

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Near‐infrared diffuse reflectance signals for monitoring spreading depolarizations and progression of the lesion in a male rat focal cerebral ischemia model

Kawauchi

Nishidate

Nawashiro

et al. 2017

J of Neuroscience Research

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In ischemic stroke research, a better understanding of the pathophysiology and development of neuroprotection methods are crucial, for which in vivo imaging to monitor spreading depolarizations (SDs) and evolution of tissue damage is desired. Since these events are accompanied by cellular morphological changes, light-scattering signals, which are sensitive to cellular and subcellular morphology, can be used for monitoring them. In this study, we performed transcranial imaging of near-infrared (NIR) diffuse reflectance at ∼800 nm, which sensitively reflects light-scattering change, and examined how NIR reflectance is correlated with simultaneously measured cerebral blood flow (CBF) for a rat middle cerebral artery occlusion (MCAO) model. After MCAO, wavelike NIR reflectance changes indicating occurrence of SDs were generated and propagated around the ischemic core for ∼90 min, during which time NIR reflectance increased not only within the ischemic core but also in the peripheral region. The area with increased reflectance expanded with increase in the number of SD occurrences, the correlation coefficient being 0.7686 (n = 5). The area with increased reflectance had become infarcted at 24 hr after MCAO. The infarct region was found to be associated with hypoperfusion or no-flow response to SD, but hyperemia or hypoperfusion followed by hyperemia response to SD was also observed, and the regional heterogeneity seemed to be connected with the rat cerebrovasculature and hence existence/absence of collateral flow. The results suggest that NIR reflectance signals depicted early evolution of tissue damage, which was not seen by CBF changes, and enabled lesion progression monitoring in the present stroke model.

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Evaluation of the Stage of Hemorrhage Using Optical Diffuse Reflectance Spectroscopy: An In Vivo Study

Takeuchi

Kawauchi

Sato

et al. 2013

Acta Neurochirurgica Supplement

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Intracerebral hemorrhage (ICH) is a common and often fatal subtype of stroke. Estimation of the stage of hemorrhage allows clinicians to know when the hemorrhage occurred, even in unconscious patients, enabling decisions to be made about the optimal management and treatment strategy. After ICH, oxidative denaturation of the hemoglobin progresses, and deoxyhemoglobin is gradually converted to methemoglobin. MRI has been used to estimate the stage of hemorrhage by evaluating the status of hemoglobin. However, there is currently no bedside device that can be used for the measurement of hemoglobin derivatives in patients with hematomas. The aim of the present study was to investigate the validity of using optical diffuse reflectance spectroscopy (ODRS) for bedside evaluation of the stage of hemorrhage. An ICH model was generated in adult Sprague-Dawley male rats by stereotactically injecting 50 μl of autologous blood into the right caudate nucleus. To analyze the hemoglobin derivatives in the hematomas, ODRS measurement was performed for the rats in vivo. In all rats, we found increased absorption at around 630 nm, which indicated the formation of methemoglobin. In conclusion, the results of the present study suggest that ODRS allows clinicians to more easily evaluate the stage of hemorrhage at the patient's bedside.

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Light-scattering signal may indicate critical time zone to rescue brain tissue after hypoxia

Cited by 19 publications

References 19 publications

Diffuse light reflectance signals as potential indicators of loss of viability in brain tissue due to hypoxia: charge-coupled-device-based imaging and fiber-based measurement

Diffuse light reflectance signals as potential indicators of loss of viability in brain tissue due to hypoxia: charge-coupled-device-based imaging and fiber-based measurement

Near‐infrared diffuse reflectance signals for monitoring spreading depolarizations and progression of the lesion in a male rat focal cerebral ischemia model

Evaluation of the Stage of Hemorrhage Using Optical Diffuse Reflectance Spectroscopy: An In Vivo Study

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