In vivo analysis of mechanism for neuronal regeneration in damaged brain by using multi-nuclear, multi-modality MRI methods

我们开发了多模式磁共振成像(MRI)技术来分析受损大脑中的神经元再生。分别是：(1)利用超快扩散加权成像获得的弥散张量图像进行纤维跟踪成像的方法；(2)利用锰增强磁共振成像(MEMRI)进行神经元激活成像的方法。该方法依赖于以下理论：(3)二维磁共振波谱(2D-MRS)可以精确分析受损脑内的各种脑代谢产物；(4)动脉自旋标记法的灌注成像；(4)以血管内水信号为示踪剂的无创脑灌注成像(动脉自旋标记法)。使用的磁共振设备是实验性磁共振成像机(4.7T Bruker Biospec和TOT VARIAN INOVA300SWB)和人体核磁共振成像机(1.5T GE Signa Horizon、1.5T西门子SYMPHONY和3.0T GE Signa Horizon)。In Fibre…更多的跟踪成像方法，基于扩散张量方向的图像清晰地显示了纤维取向的三维分布。脑梗死组可见纤维断裂。在MEMRI方法中，大鼠嗅沟、视神经和视神经内均可清晰地显示神经纤维。此外，该方法还清楚地显示了六个皮质层。该方法对于直接根据神经元的激活来检测神经元的方向和大脑结构是有用的。在2D-MRS中，在1.5T和3.0T临床MRI设备上开发了2D-JPRESS和2D-COSY。用2D-MRS方法得到常规MRS方法无法检测到的脑代谢产物谷氨酰胺/谷氨酸、谷胱甘肽、苏氨酸和GABA。2D-MRS有助于从代谢角度检测受损脑的生存能力。动脉自旋标记脑血流灌注成像可无创检测脑血流变化，结合弥散加权成像有助于了解脑梗塞半暗带区的存活情况。结论：多模式磁共振成像是一种独特的无创检测受损脑组织再生及神经细胞功能的方法。由于MRI方法评价脑功能和代谢的技术仍较多，有待于进一步研究。较少

We have developed multi-modality magnetic resonance imaging(MRI) techniques for analysis of neuronal regeneration in damaged brain. Those are ; (1)Fiber tracking imaging method by using diffusion tensor images obtained from ultra-fast diffusion weighted imaging ; (2)Neuronal activation imaging method by using manganese-enhanced MRI(MEMRI). This method depends on the theory that Mn ion can enter into neuronal cell in conjunction with Ca ion during the neuronal activation ; (3)Two dimensional MR spectroscopy(2D-MRS) by which various brain metabolites can be analyzed precisely in damaged brain ; (4)Perfusion imaging using arterial spin tagging method, (4)Non-invasive perfusion imaging of the brain by using water signal in the vessel as a tracer(Arterial spin tagging method). MRI devices used were experimental MRI machines (4.7T Bruker Biospec and TOT Varian INOVA300SWB) and a whole body MRI machine for human(1.5T GE Signa Horizon, 1.5T Siemens Symphony and 3.0T GE Signa Horizon).In fiber … More tracking imaging method, three dimensional distribution of fiber orientation was clearly demonstrated by the images based on diffusion tensor direction. Disconnection of fiber was demonstrated in cases of cerebral infarction. In MEMRI method, neuronal fibers were clearly demonstrated in rat olfactory grove, optic nerve and optic radiation. Also the six cortical layers were clearly demonstrated by this method. This method is useful to detect the neuronal orientation and brain structure directly based on the nerve cell activation. In 2D-MRS, 2D-JPRESS and 2D-COSY were developed on 1.5T and 3.0T clinical MRI devices. Brain metabolites which could not be detected by conventional MRS method were obtained by those 2D-MRS method, such as glutamine/glutamate, glutathione, threonine and GABA. 2D-MRS is useful to examine the viability of damaged brain from the metabolic point of view. The perfusion imaging using arterial spin tagging method was useful to detect the cerebral blood flow change non-invasively, and the combination with diffusion weighted imaging is useful to know the viability of penumbra region in cerebral infarction.In conclusion, the multi-modality MR methods are unique and useful to examine the regeneration of damaged brain tissue and nerve cell function non-invasively. Since there are still more techniques in MRI methods to evaluate the brain function and metabolism, further research should be continued. Less