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Proceedings Paper

In vivo transcranial measurement of light scattering in rat brains during hypoxia
Author(s): Satoko Kawauchi; Shunichi Sato; Yoichi Uozumi; Hiroshi Nawashiro; Miya Ishihara; Makoto Kikuchi
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Paper Abstract

Measurement of intrinsic optical signals (IOSs) is attractive for noninvasive, real-time monitoring of tissue viability in brains. We previously performed measurement of IOSs for a rat global ischemic brain model that was made by rapidly removing blood by saline infusion, and observed that after an induction of ischemia, a unique triphasic change in light scattering occurred. This scattering change preceded the reduction of CuA in cytochrome c oxidase which has been shown to correlate with cerebral ATP decrease. In the present study, we examined whether such triphasic scattering change can be observed in the presence of blood in vivo. Transcranial measurement of diffuse reflectance was performed using a broadband tungsten lamp for a rat brain during hypoxia that was induced by N2 inhalation. The reflectance spectral changes in the visible (500-600 nm) and near-infrared (NIR) (650-850 nm) regions were analyzed to monitor changes in hemodynamics and light scattering, respectively. After starting N2 inhalation, reflectance signals in the visible region showed an increase in deoxy-hemoglobin concentration, and about 80 s after full deoxygenation of hemoglobins, reflectance signals in the NIR region showed a similar triphasic change, which was attributable to change in light scattering. Simultaneous measurement of cerebral EEG showed that neuronal activity ceased about 50 s before this triphasic scattering change. These results show that light scattering will become an important indicator of loss of tissue viability in brain; brain tissue can probably be saved if reoxygenation is achieved before starting this scattering change.

Paper Details

Date Published: 24 February 2009
PDF: 6 pages
Proc. SPIE 7187, Biomedical Applications of Light Scattering III, 71870U (24 February 2009); doi: 10.1117/12.807967
Show Author Affiliations
Satoko Kawauchi, National Defense Medical College (Japan)
Shunichi Sato, National Defense Medical College (Japan)
Yoichi Uozumi, National Defense Medical College (Japan)
Hiroshi Nawashiro, National Defense Medical College (Japan)
Miya Ishihara, National Defense Medical College (Japan)
Makoto Kikuchi, National Defense Medical College (Japan)

Published in SPIE Proceedings Vol. 7187:
Biomedical Applications of Light Scattering III
Adam Wax; Vadim Backman, Editor(s)

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