Paper
18 February 2011 Functional near infrared brain imaging with a brush-fiber optode to improve optical contact on subjects with dense hair
Bilal Khan, Chester Wildey, Robert Francis, Fenghua Tian, Mario I. Romero, Mauricio R. Delgado, Nancy J. Clegg, Linsley Smith, Hanli Liu, Duncan L. MacFarlane, George Alexandrakis
Author Affiliations +
Abstract
A major obstacle in functional near infrared spectroscopy (fNIRS) and imaging is poor optical contact of the optodes with the scalp due to obstruction by hair. To overcome this problem a novel brush-fiber extension was made as an attachment to existing commercial flat-face fiber bundle optodes. The goal was that the brush-fiber extension would thread through hair and improve optical contact on subjects with dense hair. Simulations and experiments were performed to assess the magnitude of these improvements. Firstly, a Monte Carlo (MC) simulation of photon propagation through the scalp with hair and hair follicles was performed showing a drop in light transmission for different hair densities in the range of 3 to 9 dB. Similar levels of signal loss at individual optodes were determined experimentally in preliminary measurements on a human subject, when comparisons were made for finger tapping activation measurements with and without the brush-fiber extensions. The effects of such losses on reconstructed images were also simulated by using neutral density filters during tissue phantom measurements. As brush-fibers attenuated the signal by approximately 2.5 dB due to imperfect optical contact with the flat-face optode tips we explored the idea of using larger diameter brush-fibers to overcome that loss.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bilal Khan, Chester Wildey, Robert Francis, Fenghua Tian, Mario I. Romero, Mauricio R. Delgado, Nancy J. Clegg, Linsley Smith, Hanli Liu, Duncan L. MacFarlane, and George Alexandrakis "Functional near infrared brain imaging with a brush-fiber optode to improve optical contact on subjects with dense hair", Proc. SPIE 7883, Photonic Therapeutics and Diagnostics VII, 78834V (18 February 2011); https://doi.org/10.1117/12.873839
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Cited by 5 scholarly publications and 1 patent.
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KEYWORDS
Signal detection

Signal attenuation

Signal to noise ratio

Monte Carlo methods

Sensors

Tissue optics

Hemodynamics

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