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Effect of mechanical optical clearing on near‐infrared spectroscopy
Author(s) -
Idelson Christopher R.,
Vogt William C.,
KingCasas Brooks,
LaConte Stephen M.,
Rylander Christopher G.
Publication year - 2015
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.22373
Subject(s) - biomedical engineering , near infrared spectroscopy , signal (programming language) , materials science , computer science , medicine , optics , physics , programming language
Near‐infrared Spectroscopy (NIRS) is a broadly utilized technology with many emerging applications including clinical diagnostics, sports medicine, and functional neuroimaging, to name a few. For functional brain imaging NIR light is delivered at multiple wavelengths through the scalp and skull to the brain to enable spatial oximetry measurements. Dynamic changes in brain oxygenation are highly correlated with neural stimulation, activation, and function. Unfortunately, NIRS is currently limited by its low spatial resolution, shallow penetration depth, and, perhaps most importantly, signal corruption due to light interactions with superficial non‐target tissues such as scalp and skull. In response to these issues, we have combined the non‐invasive and rapidly reversible method of mechanical tissue optical clearing (MOC) with a commercially available NIRS system. MOC utilizes a compressive loading force on tissue, causing the lateral displacement of blood and water, while simultaneously thinning the tissue. A MOC‐NIRS Breath Hold Test displayed a ∼3.5‐fold decrease in the time‐averaged standard deviation between channels, consequentially promoting greater channel agreement. A Skin Pinch Test was implemented to negate brain and muscle activity from affecting the recorded signal. These results displayed a 2.5–3.0 fold increase in raw signal amplitude. Existing NIRS instrumentation has been further integrated within a custom helmet device to provide a uniform force distribution across the NIRS sensor array. These results showed a gradual decrease in time‐averaged standard deviation among channels with an increase in applied pressure. Through these experiments, and the development of the MOC‐NIRS helmet device, MOC appears to provide enhancement of NIRS technology beyond its current limitations. Lasers Surg. Med. 47:495–502, 2015. © 2015 Wiley Periodicals, Inc.