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Journal of Biomedical Optics • Open Access

Detection of an unstable and/or a weak probe contact in a multichannel functional near-infrared spectroscopy measurement
Author(s): Shinji Umeyama; Toru Yamada

Paper Abstract

Multichannel functional near-infrared spectroscopy measurements involve the placement of many probes on a subject’s head. A stable close contact between the probe and head surface is essential. We propose a way to detect two types of problematic probe contacts from the measurement data: an unstable contact whose light transmission easily fluctuates with body motion, and a weak contact whose light transmission is constantly small. An unstable contact causes large baseline fluctuation, whereas a weak contact causes large noise. Because absorbance changes caused by body motion and noise show different spectroscopic properties from the tissue hemoglobin absorption, they have a component orthogonal to the plane spanned by hemoglobin molar extinction coefficient vectors. We use this information to detect unstable and/or weak contacts. Probes are shared by different channels, and this sharing configuration is determined by the probe arrangement. Thus, the baseline fluctuation and noise of the channels are related to contact instability and weakness of the probe according to the probe arrangement. Unstable and/or weak probes are determined by solving an inverse problem of this relation. Problematic probes can be effectively determined using the proposed method.

Paper Details

Date Published: 3 April 2013
PDF: 10 pages
J. Biomed. Opt. 18(4) 047003 doi: 10.1117/1.JBO.18.4.047003
Published in: Journal of Biomedical Optics Volume 18, Issue 4
Show Author Affiliations
Shinji Umeyama, National Institute of Advanced Industrial Science and Technology (Japan)
Toru Yamada, National Institute of Advanced Industrial Science and Technology (Japan)

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