Ichiro ODA^*, Yukihisa WADA, Sadao TAKEUCHI, Ikuo KONISHI^† and Yoshio TSUNAZAWA

Technology Research Laboratory, Shimadzu Corporation, 3-9-4 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237, Japan

(Received February 17, 2003; Accepted June 24, 2003)

This paper describes a new near infrared (NIR) spectroscopic imager that has an expanded detection dynamic range intended for measurements with various transmitter-receiver (T-R) distances. Simultaneous multi-distance measurements for 48 points of the human forehead were performed to record brain activation by a mental test called digit span. Similarity Index (SI) analysis of 48 time-course curves was introduced for the evaluation of the result. A new mapping method toward depth direction is also shown for total hemoglobin and SI values. Simultaneous multi-distance measurements are useful for the brain functional analysis to distinguish depth variation.

Key words: multi-channel near infrared spectroscopy (NIRS), multi-distance measurement, detection gain control, topographic Image, brain functional imaging

^*E-mail address: oda@shimadzu.co.jp
^†E-mail address: ikonishi@shimadzu.co.jp