| Brain ischemia is one of the common diseases threatening the health of human, which is characterized by its high incidence, mortality rate, mutilation rate as well as recurrence rate. How to diagnose in the early phase and to treat the disease remains the hot point seriously concerned by clinical medicine. By now, the most effective and perspective way to treat acute brain ischemia is the therapy of thrombolytic treatment in its hyper acute phase(<6h). Choosing the best time for thrombolytic treatment is the most important otherwise hemorrhagic brain infarction, hypoxia of local brain tissue caused by reperfusion will ensue which may lead to deterioration and even death. However routine examinations of MRI and CT cannot distinguish the lesion of brain ischemia in the hyper acute phase and at this time the clinical signs and symptoms can't give enough proof to localize the lesion as well. Thus how to localize the lesion as well as its dimension and degree is very critical.Recently the development of functional MRI including DWI, PWI, MRS, MTC makes it possible to diagnose the brain ischemia quickly and accurately in the early phase, which will provide us pertinent hemodynamics data and metabolism information.This study is to discuss the application value of fMRI in the early phase diagnosis of brain ischemia and the instruction of clinical treatment as well as prognosis evaluation through the investigation of animal model of acute brain ischemia and patients.Objective:1. Using fMRI and routine MRI on rat acute brain ischemia model to evaluate the value of fMRI to diagnose acute brain ischemia in the early phase.2. Using DWI, PWI techniques on rat acute brain ischemia reperfusion model to discuss and study the etiology of brain ischemia.3. Using DWI, PWI technique on animal model to observe the serial dynamic changes of the rat brain cortex with the injection of IMP before ischemia was created. And to evaluate the application value of fMRI in searching the functioning mechanism and accessing the therapeutic effect of neuron protectants.4. To explore the clinical value of DWI and FLAIR in the diagnosis of acute cerebral infarction.Methods:1. Establish the rat acute brain ischemia model with 42 male SD rats (280-320g) divided randomly into operation group (A1, n=28) and non-operation group (A2, n=14). Single strand of nylon was put into the right middle cerebral artery to obstruct it. SOmins, Ih, 2h, 3h, 6h, 12h, 24h after operation routine MRI and fMRI examination were performed respectively on rat model and the results was compared. Microscopy was used to observe the cells and tissues' change of brain. After that, the relationship between morphological, metabolic changes detected by fMRI and histological changes of brain tissue was discussed.2. The acute brain ischemia-reperfusion rat models with 45 male SD rats (280-320g) were divided into 3 groups (B1, B2. B3, n1,2,3=15). The brain perfusion was rebuilt when the nylon strand were drew out after 30mins, 1h, 2h respectively. Routine MRI and fMRI scan was performed before reperfusion and 1h, 2h, 3h, 6h, 12h, 24h after reperfusion, and the results of the 3 groups were compared.3. 30 male SD rats were divided into 2 groups (C1, C2, n1=15) with TMP 100mg/kg and saline 1ml injected into abdominal cavity respectively before ischemia was created and after 2h obstruction of middle cerebral artery the nylon strand was drew out. Routine MRI and fMRI scan was performed before reperfusion and 1h, 2h, 3h, 6h, 12h, 24h after reperfusion, and the results were compared.4. 60 cases of acute cerebral infarction, including 7 cases of super acute stage (<6h), 24 cases of acute stage (6-24h), and 29 cases of subacute stage (24-72h), were examined with T1WI, T2WI, FLAIR and DWI sequences. The extent, boundary and contrast of lesions on all images were compared. ADC and rADC of the lesions were calculated.Result:1. (1) In Al group, all rats showed high intense signal on DWI after ischemia was created...
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