脑梗死是致残率最高的疾病之一，探索脑梗死后神经功能的脑重塑机制，是国内外研究所面临的重大问题。研究发现幕上脑梗死后50%-70%伴有交叉性小脑失联络（CCD），且CCD与患者预后密切相关，但CCD发生的脑机制及运动功能预后的代偿机制尚不清楚。脑梗死病灶导致皮层-桥脑-小脑通路损伤，可能是CCD的主要原因。PET和MRI是评价脑梗死后CCD的有力手段，PET能提供脑血流和代谢信息，静息态MRI功能成像（fMRI）能提供脑功能连接情况，扩散张量成像（DTI）能显示纤维束改变。因此本研究利用目前国际最前沿的一体化PET/MRI，进行PET脑血流代谢和fMRI、DTI同步扫描，分析CCD患者脑血流、代谢连接、功能连接和白质纤维束的变化情况及其相关性，并长期纵向随访，揭示影像学改变与临床运动功能预后的关系，阐明脑梗死后CCD患者运动功能障碍及预后脑机制，对降低患者致残率，指导临床康复治疗有重要意义。

Stroke is a disease with high disability rate, and at least 50%-70% accompany with crossed cerebellar diaschisis (CCD), which is an important prognostic indicator of stroke recovery. Therefore, it is important to explore the cerebral mechanism of functional recovery and improve outcome in patients with in farction. Studies have shown that disrupted of cerebrocerebellar circuitry may cause crossed cerebellar diaschisis, but its mechanism and the relationship with the outcome of motor function are poorly understood. PET and MRI are versatile technique increasingly used to evaluate acute stroke. PET can provide the blood flow and matabolic information. Resting functional MRI (fMRI) and diffusion tensor imaging (DTI) can delineate functional connection and corticospinal tract injury. In this study, we will use simultaneous PET/MRI to study the cerebral blood flow, glucose metabolism, functional connection and corticospinal tract in the patients who had CCD after supratentorial infarction, estimate the relationship between blood flow, metabolism and functional connection and assess the outcomes during follow-up, which can help us to state the brain mechanism of motor dysfunction and recovery. In summary, our proposal, if successful, can be quickly translated to guide effective rehabilitation treatment of stroke patients, and develop more effective treatment strategies. This will play an important role in reducing disability rate and burden of family and society.