A 200-Channel Imaging System of Muscle Oxygenation Using CW Near-Infrared Spectroscopy

Masatsugu NIWAYAMA  Katsuyuki YAMAMOTO  Daisuke KOHATA  Kosuke HIRAI  Nobuki KUDO  Takafumi HAMAOKA  Ryotaro KIME  Toshihito KATSUMURA  

IEICE TRANSACTIONS on Information and Systems   Vol.E85-D   No.1   pp.115-123
Publication Date: 2002/01/01
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on Measurements and Visualization Technology of Biological Information)
Category: Optical Imaging
near-infrared spectroscopy,  tissue oxygenation,  skeletal muscle,  functional imaging,  

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We have developed a 200-channel imaging system that enables measurement of changes in oxygenation and blood volume and that covers a wider area (45 cm 15 cm) than that covered by conventional systems. This system consisted of 40 probes of five channels, a light-emitting diode (LED) driver, multiplexers and a personal computer. Each probe was cross-shaped and consisted of an LED, five photo diodes, and a current-to-voltage (I-V) converter. Lighting of the LEDs and acquisition of 200-channel data were time-multiplexed. The minimum data acquisition time for 200 channels, including the time required for calculation of oxygenation and monitoring of a few traces of oxygenation on a computer display, was about 0.2 s. We carried out exercise tests and measured the changes in oxy- and deoxy-hemoglobin concentrations in the thigh. Working muscles in exercises could be clearly imaged, and spatio-temporal changes in muscle oxygenation during exercise and recovery were also shown. These results demonstrated that the 200-channel imaging system enables observation of the distribution of muscle metabolism and localization of muscle function.