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Journal of Biomedical Optics • Open Access

Accelerometer-based method for correcting signal baseline changes caused by motion artifacts in medical near-infrared spectroscopy
Author(s): Jaakko Virtanen; Kalle M. Kotilahti; Risto Ilmoniemi; Tommi E. J. Noponen; Juha Virtanen

Paper Abstract

In medical near-infrared spectroscopy (NIRS), movements of the subject often cause large step changes in the baselines of the measured light attenuation signals. This prevents comparison of hemoglobin concentration levels before and after movement. We present an accelerometer-based motion artifact removal (ABAMAR) algorithm for correcting such baseline motion artifacts (BMAs). ABAMAR can be easily adapted to various long-term monitoring applications of NIRS. We applied ABAMAR to NIRS data collected in 23 all-night sleep measurements and containing BMAs from involuntary movements during sleep. For reference, three NIRS researchers independently identified BMAs from the data. To determine whether the use of an accelerometer improves BMA detection accuracy, we compared ABAMAR to motion detection based on peaks in the moving standard deviation (SD) of NIRS data. The number of BMAs identified by ABAMAR was similar to the number detected by the humans, and 79% of the artifacts identified by ABAMAR were confirmed by at least two humans. While the moving SD of NIRS data could also be used for motion detection, on average 2 out of the 10 largest SD peaks in NIRS data each night occurred without the presence of movement. Thus, using an accelerometer improves BMA detection accuracy in NIRS.

Paper Details

Date Published: 1 August 2011
PDF: 10 pages
J. Biomed. Opt. 16(8) 087005 doi: 10.1117/1.3606576
Published in: Journal of Biomedical Optics Volume 16, Issue 8
Show Author Affiliations
Jaakko Virtanen, Aalto Univ. School of Science and Technology (Finland)
Kalle M. Kotilahti, Aalto Univ. School of Science and Technology (Finland)
Risto Ilmoniemi, Aalto Univ. School of Science and Technology (Finland)
Tommi E. J. Noponen, Turku Univ. Hospital (Finland)
Juha Virtanen, GE Healthcare (Finland)

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