Diffuse near-infrared reflectance spectroscopy during heatstroke in a mouse model: pilot study

Area of Science:

• Biomedical Optics
• Neuroscience
• Hyperthermia Research

Background:

• Heatstroke is a life-threatening condition characterized by core body temperature above 40°C and central nervous system dysfunction.
• Current methods for monitoring temperature during heatstroke are limited, especially in small animal models.
• Pathological changes in brain tissue during heatstroke affect its composition and structure.

Purpose of the Study:

• To assess the feasibility of using diffuse reflectance spectroscopy (DRS) to monitor internal brain tissue temperature during heatstroke in a mouse model.
• To investigate the correlation between temperature changes and optical scattering signals in brain tissue.
• To establish a reflectance-temperature index for estimating internal brain temperature variations.

Main Methods:

• Heatstroke was induced in anesthetized mice by exposure to high ambient temperatures.
• Diffuse reflectance spectroscopy (DRS) was employed, illuminating brain tissue through the intact scalp (650-1000 nm spectral region).
• Reflected spectra were analyzed for changes in absorbance intensity and scattering signals correlated with rectal temperature increases.

Main Results:

• Increased temperature during heatstroke caused significant changes in optical scattering signals, indicating structural alterations in brain tissue.
• Peak absorbance intensity and its second derivative showed an exponential correlation with temperature.
• A novel reflectance-temperature index was established, correlating well with measured temperatures.

Conclusions:

• Diffuse reflectance spectroscopy (DRS) is a feasible method for monitoring internal brain tissue temperature variations during heatstroke in small animal studies.
• DRS can detect temperature-induced changes in neural tissue properties.
• This study presents a novel approach for assessing hyperthermia's impact on brain tissue using optical spectroscopy.