Development of Magnetic Resonance Imaging of Neuronal activity and its application to functional brain imaging

本研究试图利用磁共振成像技术，发展神经元活动的地形图成像，以应用于新的脑功能标测。其基本思想是结合显微成像和超快扩散磁共振成像，检测神经元电活动过程中神经细胞膜之间的水扩散。研究项目包括三个部分。第一是发展了利用MRI方法对神经元活动成像的技术。第二是将该技术应用于实验动物的研究，并检验该技术是否可以应用于脑功能图。三是将该技术应用于临床1.5T磁共振成像仪，并探讨其在人体应用的可能性。在最初的两年中，研究重点是开发实验性MRI机器（7.0 Unity INOVA 300 SWB，Varian，USA）的硬件。由于预算的削减，我们无法获得超超强梯度 ...更多信息 线圈（20高斯/厘米）。我们用传统的梯度线圈（2Gaus/cm）和新引进的成像阵列处理器研制了显微成像系统。在此基础上，我们还尝试制作了新推出的微成像阵列处理器。除此之外，我们还尝试在小型实验MRI系统（Mrsoon，Jyonan-Denshi，Tukuba）上进行显微成像，该系统工作在临床MRI扫描仪的磁体上。我们开发的脉冲序列是基于回波平面成像（EPI）。在90度脉冲之后，在180度制备脉冲之前和之后施加扩散探测梯度，并且检测受水穿过神经元细胞膜的扩散影响的信号。采用常规梯度法可以得到矩阵尺寸为10微米的超快扩散加权显微图像。但到目前为止，我们还不能在实验动物身上得到这种扩散显微图像。其原因可能是梯度强度不足以获得更小的基体和更强的扩散梯度能力。因此，我们最初需要的超超强梯度是进行这种实验所必需的。同样对于临床扫描仪的应用，它需要更强的梯度和更强的磁场，如3.0T或4.0T。最后，我们想强调的是，如果我们能够得到更强大的扫描仪，将有可能通过使用MRI获得神经元活动图像。少

We tried to develop the topographic imaging of neuronal activity by using magnetic resonance imaging (MRI) techniques for applying to new functional brain mapping. The basic idea is to detect the water diffusion associated between the neuronal cell membrane during the neuronal electrical activity by the combination with microimaging and ultra-fast diffusion MR imaging. The research projects consisted of three parts. The first was to develop the technique of imaging of neuronal activity by using MRI method. The second was to apply this technique to study the experimental animals and to examine if this can be applied to the brain functional mapping. The third was to apply this technique to the clinical 1.5T MRI sacnner and to examine the possibility of human application. During initial two years, the study was focused on developing the hardware of experimental MRI machine (7.0 Unity INOVA300SWB, Varian, USA). Due to the cut of the budget, we could not get the ultra-super strong gradient … More coil (20Gause/cm). We developed the microimaging system using the conventional gradient coil (2Gaus/cm) and the imaging array processor which was newly intoduced. In addition to this study, we tried to make the microimaging array processor which was newly intoduced. In addition to this study, we tried to make the microimaging on the small experimental MRI system (Mrmics, Jyonan-Denshi, Tukuba) which works in the magnet of clinical MRI scanner. The pulse sequence we developed is based on the Echo Planar Imaging (EPI). Following the 90 degree pulse, diffusion probing gradients were applied before and after 180 degree preparation pulse and signal which affected by the diffusion of water across the neuronal cell membrane was detected. We could obtain the ultra-fast diffusion weighted microimage with matrices size of 10 mirometer each by using the conventional gradient. But so far, we could not get this kind of diffusion microimage on the experimental animal. The reason would be that the gradient strength is not enough to get more small matrix and more strong diffusion gradient power. Therefore, the ultra-super strong gradient which we initially required is essential to perform this kind of experiment. Also for the application to the clinical scanner, it requires the more strong gradient and more strong magnetic field such as 3.0T or 4.0T. Finally, we would like to stress that it will be possible to obtain the neuronal activity image by using MRI if we can get more powerful scanner. Less