Research Papers

New method of estimating wavelength-dependent optical path length ratios for oxy- and deoxyhemoglobin measurement using near-infrared spectroscopy

[+] Author Affiliations
Shinji Umeyama, Toru Yamada

Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology, Center 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568, Japan

J. Biomed. Opt. 14(5), 054038 (October 27, 2009). doi:10.1117/1.3253350
History: Received May 01, 2009; Revised August 03, 2009; Accepted August 21, 2009; Published October 27, 2009
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In near-infrared spectroscopy (NIRS), concentration changes in oxy- and deoxyhemoglobin are calculated using an attenuation change of the measurement light and by solving a linear equation based on the modified Lambert-Beer law. While solving this equation, we need to know the wavelength-dependent mean optical path lengths of the measurement lights. However, it is very difficult to know these values by a continuous-wave-type (CW-type) system. We propose a new method of estimating wavelength-dependent optical path length ratios of the measurement lights based on the data obtained by a triple wavelength CW-type NIRS instrument. The proposed method does not give a path length itself, but it gives a path length ratio. Thus, it is possible to obtain the accurate hemoglobin concentration changes without cross talk, although the method cannot contribute to the quantification of the absolute magnitude of hemoglobin changes. The method is based on the principle that two possible estimations of hemoglobin concentration changes calculated using a triple-wavelength measurement system should be identical. The method was applied to the experimental data of human subjects’ foreheads. The estimated path length ratios were very similar to literature values obtained by using picosecond laser pulses and a streak camera detector [].

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© 2009 Society of Photo-Optical Instrumentation Engineers

Citation

Shinji Umeyama and Toru Yamada
"New method of estimating wavelength-dependent optical path length ratios for oxy- and deoxyhemoglobin measurement using near-infrared spectroscopy", J. Biomed. Opt. 14(5), 054038 (October 27, 2009). ; http://dx.doi.org/10.1117/1.3253350


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