抄録
The fact that neuronal electric activity in the brain causes an increase in regional cerebral flood flow has given the basis for the functional imaging of human as well as animal brains. fMRI and PET are well known modalities based on the above. Near-infrared spectroscopy (NIRS), which has been first developed for non-invasive monitoring of brain oxygenation in clinical field. Then, f-NIRS appeared which could detect the changes in blood oxygenation in the brain associated with the neural activity, then, near-infrared optical imaging (NIR-imaging) started to obtain functional optical mapping. However, there seem many difficulties for imaging. In order to overcome the problems associated with NIR-imaging such as the lack of the quantification and poor spatial resolution, we developed a 64-channel time-resolved optical imaging system, by which we could obtain quantitative functional images of human brain activity. Reflectance tomographic images of the changes in oxy-hemoglobin, deoxy-hemoglobin, and total-hemoglobin, associated with neural activation were obtained, and given as absolute concentration changes. Then, the obtained optical functional images were superimposed on 3-D images of the subject's brain reconstructed from MRI. The optical imaging system employed here can be applied to the subjects of all ages and be used at the bedside as well. By simplifying and miniaturizing the imaging system, we could construct a conventional single channel oxygen monitor for clinical use, by which we could quantify the changes of [oxy-, deoxy- and total Hb] during neuronal activation in each subject and, therefore, statistical analysis became possible. [Jpn J Physiol 54 Suppl:S3 (2004)]
