Development of multi-modality magnetic resonance methods for cerebral blood flow, metabolism and brain function on ultra-high magnetic field and its clinical application

我们发展了多模态磁共振成像（MRI）技术，用于在超高磁场下分析脑循环、脑功能和代谢。这些是;（1）快速^1H化学位移成像（CSI）方法和2D-COSY方法检测脑内各种代谢物，（2）使用超快速MRI（EPI-DWI）的弥散加权成像，（3）使用动脉自旋标记法的Per融合成像，（4）在超高场磁体上改进功能MRI（fMRI）并开发新的检测神经细胞兴奋的fMRI方法。使用的系统是一台实验性的MRI机器（7.0T INOVA 300 SWB，Varian）和用于人的全身MRI机器（3.0 T，Signa Horizon，GE）。在^1H-CSI中，获得了比低磁场系统更高的信号强度，并以高空间分辨率显示了各种代谢物的分布，如N-乙酰天冬氨酸（NAA）、谷氨酰胺/谷氨酸盐、胆碱、肌酸、肌醇乳酸等。NAA的减少， ...更多信息 观察到US脑紊乱，表明神经元的损失。在恶性肿瘤和梗死的缺氧细胞组分中观察到乳酸增加。在二维COSY法中，谷氨酰胺和谷氨酸被清楚地分离，并可检测到少量的氨基酸如牛磺酸。在EPI-DWI中，在超急性期（例如发病后30分钟）检测到脑梗死。根据EPI-DWI数据计算的弥散张量成像（DTT）和纤维追踪成像（FTR）可清晰显示神经纤维的方向。采用动脉自旋标记法（FAIR）的灌注成像可用于检测脑血流的相对变化，但即使在3.0T系统上仍需要更高的灵敏度。EPI-DWI和灌注成像的结合可能指示受损脑组织的可逆性。在功能性磁共振成像（fMRI）中，在对应于每个激活任务（如手指运动、光刺激和听单词）的皮层区域中的超高磁场上观察到信号强度的增加。功能磁共振成像也通过想象等复杂任务获得。作为一种新的功能磁共振成像方法，我们尝试将显微成像和EPI-DWI结合起来，发展神经元活动的地形图成像。从理论上讲，在兴奋的神经细胞中可以观察到水分子的流入。虽然我们可以获得每个矩阵大小为10微米的超快速扩散加权显微图像，但到目前为止，它还不足以直接检测实验动物上神经细胞的流入。原因可能是梯度强度对于这个实验来说不够。实验需要更强的梯度和更强的磁场。然而，多模态MR方法是非侵入性检查脑代谢和功能以及检查各种脑疾病的病理生理学的独特且有用的方法。从这个意义上说，应继续进行进一步的研究。少

We have developed multi-modality magnetic resonance imaging (MRI) techniques for analysis of cerebral circulation, brain functions and metabolism on ultra-high magnetic field. Those are; (1) Fast ^1H chemical shift imaging (CSI) method and 2D-COSY method to detect various metabolite in the brain, (2) Diffusion-weighted imaging using ultra fast MRI (EPI-DWI), (3) Per fusion imaging using arterial spin tagging method, (4) Improvement of functional MRI (fMRI) on ultra-high field magnet and development of new fMRI method which detect nerve cell excitation. Systems used were an experimental MRI machine (7.0 T INOVA300SWB, Varian) and a whole body MRI machine for human (3.0 T, Signa Horizon, GE).In ^1H-CSI, higher signal intensity was obtained than lower magnetic field systems and the distribution of various metabolites was visualized with high spatial resolution, such as N-acetyl aspartate (NAA), glutamine/glutamate, choline, creatine, inositol, lactate and etc. The decrease of NAA in vario … More us brain disorders were observed, indicating the loss of neurons. Increased lactate was observed in hypoxic cell fractions in malignant tumors and infarction. In 2D-COSY method, glutamine and glutamate were clearly separated and small amount of ammo acid such as taurine could be detected. In the EPI-DWI, cerebral infarction is detected at an ultra-acute stage such as 30 minutes after the onset. The diffusion tensor imaging (DTT) and fiber tracking imaging, which were calculated from the data of EPI-DWI, indicated the direction of nerve fiber clearly. The perfusion imaging using arterial spin tagging method (FAIR) is useful to detect the relative changes in cerebral blood flow, but it still requires more sensitivity even on a 3.0T system. The combination of EPI-DWI and Perfusion Imaging can possibly indicate the reversibility of damaged brain tissue. In functional MRI (fMRI), an increase of signal intensity was observed on the ultra-high magnetic field in the cortical area corresponding to each activation task such as finger movements, photic stimulation and hearing words. The fMRI was also obtained by complex tasks such as imagination. As a new fMRI method, we tried to develop topographic imaging of neuronal activity by the combination with microimaging and EPI-DWI. Theoretically it is, possible to observe the influx of water molecule in the excited nerve cell. Although we could obtain the ultra-fast diffusion weighted microimage with matrices size of 10 mirometer each, it is not enough to detect the influx of nerve cell directly so far on the experimental animal. The reason would be that the gradient strength is not enough for this experiment. More strong gradient and more strong magnetic field is necessary for this experiments. Nevertheless, the multi-modality MR methods are unique and useful methods to examine the brain metabolism and function non-invasively and to examine pathophysiology of various cerebral disorders. In this sense, further research should be continued. Less