Applied Research for Non-Invasive Monitoring of Brain Functions with Near-Infrared Light Computed Tomography

对于近红外光计算机断层扫描（NIR-CT）大鼠脑成像，我们研究了四种“权重函数”和三种重建算法。对高散射系数（1.00/mm）和高吸光度系数（0.20/mm）的幻影进行蒙特卡罗模拟计算得到的权函数a与共轭梯度法（CGM）相结合的算法对动物头部成像效果最好。我们成功地成像了沙鼠颈动脉闭塞后脑血流量的减少。我们还得到了重新打开动脉后脑血流恢复的图像。采用双波长成像方法，可以检测沙鼠头部血红蛋白氧合状态的变化。我们给大鼠注射了一种叫戊四唑的惊厥药后，对其脑血流量的增加进行了成像。在这些实验中，我们成功地用NIR-CT成像了大脑活动的增加和减少。

For imaging of rat brain with near-infrared light computed tomography (NIR-CT), we examined four types of 'weight functions' and three types of reconstruction algorithm. The combination of weight function 'a', that is calculated from the Monte Carlo simulation of phantoms with high scattering coefficient (1.00/mm) and high absorbance coefficient (=0.20/mm) and conjugate gradient method (CGM) as an algorithm was the best for imaging animal heads.We succeeded to image the decrease of cerebral blood flow of a gerbil after occlusion of carotid artery. We also got the image of cerebral blood flow recovery after re-open the artery. With 2-wavelength imaging method, we could detect the change of oxygenation sate of hemoglobin in the head of gerbil. We imaged the increase of cerebral blood flow after the injection of pentylenetetrazole, a convulsive drug to a rat.In these experiments, we succeeded to image the increase as well as decrease of cerebral activity with NIR-CT.