Abstract
Light in the near-infrared range (700-1, 200nm) penetrates living tissues including the skull. Oxy- and deoxy-hemoglobin contents in living tissue can be measured from the absorbance in this range. Myoglobin and cytochrome oxidase also have their absorbance in this range. Therefore, we carried out near-infrared computed tomography by a modification of the method for X-ray CT for humans. Three semiconductor lasers were used as light sources with a laser beam scanner. The transmitted light was measured with a linear detector equipped with 25 photomultipliers. With this device, we constructed images of the heads of anesthetized rats from the differences between the absorbance data at 780 and 805nm. The brightness of the head images increased in rats with ischemia induced by occlusion of four vessels (carotid). The ischemic area in the central part of the head was shown on exchange transfusion of the blood with perfluorochemical emulsion.
