Experimental Study Of Functional Imaging In The Acute Cerebral Venous Occlusion And Investigating The Directive Value For Clinical Treatment

Partâ… : Modeling of an acute experimental cerebral venous occlusionObjective: To establish a stable animal model of an acute experimental cerebral venous occlusion to be similar to clinical disease.Methods: 28 New Zealand white rabbits were randomly divided into 2 groups, including experiment group (n=24) and control group (n=4). T2WI and DWI were performed at an interval of 1, 3, 6, 12, 24 and 48h after operation which injected CAP solution into left or right internal jugular vein and by ligation of the bilateral external jugular veins. Brain parenchymal lesions were observed dynamically and compared with pathological changes.Results:21 rabbits in experiment group were operated successfully. The operation of 3 rabbits failed because of misoperation and anesthesia. No abnormal appearance was observed in 3 rabbits on T2WI and DWI sequences. Brain parenchymal lesions were demonstrated by MRI in cortical and sub-cortical areas. The early pathological changes were only detected with DWI (within 1h), and then the lesions were also detected with T2WI after 3h. Brain parenchymal lesions in microscopically were mainly vasogenic edema and followed by necrosis after 12h. No abnormal changes were observed in control group.Conclusion: Modeling of injection of CAP solution into left or right internal jugular vein and ligation of the bilateral external jugular veins in rabbits is feasible. The model is suitable for pathophysiological and radiological studies of acute cerebral venous occlusion. Partâ…¡: Comparison of diffusion weighted imaging and histopathology in experimental study of acute cerebral venous occlusionObjective: To observe the evolution of lesion on animal model of acute cerebral venous occlusion by diffusion weighted imaging (DWI), diffusion tensor imaging (DTI) and histopathology, and investigate the value of this kind of model in the disease's study.Methods: 28 New Zealand white rabbits were randomly divided into 2 groups, including experiment group (n=24) and control group (n=4). T2WI, DWI and DTI were performed at an interval of 1, 3, 6, 12, 24 and 48h after operation which injected CAP solution into left or right internal jugular vein and by ligation of the bilateral external jugular veins. The evolution of the volume of DWI abnormality, apparent diffusion coeffient (ADC) values, fractional anisotropy (FA) values and hemodynamic changes were observed in each group. The data were compared with pathological findings.Results:The early pathological changes were only detected with DWI (within 1h), and then the lesions were also detected with T2WI after 3h. The volume of DWI abnormality was bigger than T2WI abnormality before 6h (P<0.01). No obvious difference of the volume on T2WI abnormality and DWI was found after 12h, 24h and 48h (t=1.467, 0.996, 2.017 respectively; P>0.05). The ADC values of the brain parenchymal lesions decreased at the early stage and increased subsequently. At 1h after operation, FA values of the brain parenchymal lesions slightly increased and subsequently decreased gradually after 3h. Cytotoxic edema emerged after 1h and 3h, then vasogenic edema emerged after 3h and gradually became the main patho-histology findings. Large amount of necrosis was found after 12h. No abnormal changes were observed in control group.Conclusion: DWI and DTI are accurate in evaluating brain parenchymal lesions and hemodynamics of acute cerebral venous occlusion, and are useful for early clinic treatment and prognosis assessment. Partâ…¢: Correlation study between CT perfusion imaging and histopathology of acute experimental cerebral venous occlusionObjective: To evaluate model of acute cerebral venous occlusion with computed tomography perfusion (CTP) and histopathological.Methods: 28 New Zealand white rabbits were randomly divided into 2 groups, including experiment group (n=24) and control group (n=4). CTP was performed at an interval of 1, 3, 6, 12, 24 and 48h after operation which injected CAP solution into left or right internal jugular vein and by ligation of the bilateral external jugular veins. The hemodynamic changes were observed in each group. The CTP data were compared with pathological findings.Results:21 rabbits in experiment group were operated successfully. The operation of 3 rabbits failed because of misoperation and anesthesia. No abnormal appearance was observed in 2 rabbits on CT perfusion imagings. Cerebral blood volume (CBV) slightly increased or noral, cerebral blood flow (CBF) slightly decreased and mean transit time (MTT) prolonged slightly in the lesions after 1~3h. Both CBV and CBF decreased in the center of the lesions, while CBV increased, normal or decreased, CBF decreased in the marginal zone after 6~12h. CBV and CBF decreased obviously both in the center and marginal zone after 12~24h. There was obvious difference among CBV%, CBF% and MTT% in the center and marginal zone of the lesions at each time interval (P<0.05). The volume of CBF abnormality was bigger than DWI abnormality after 1h, 3h and 6h (t=3.707, 4.029, 4.015 respectively; P<0.01). No obvious difference of the volume on CBF abnormality and DWI was found after 12h, 24h and 48h (t=0.676, 1.356, 2.306 respectively; P>0.05). Brain parenchymal lesions in microscopically were mainly vasogenic edema and followed by necrosis after 12h. No abnormal changes were observed in control group.Conclusion: CT perfusion imaging is accurate and sensitive in evaluation hemodynamics of acute cerebral venous occlusion and is useful in the early evaluation of the consequences for brain parenchymal lesions. Moreover, CT perfusion imaging is favourable for early clinic treatment and prognosis assessment. Partâ…£: Preliminary research of the therapeutic widow in brain parenchymal lesion of acute cerebral venous occlusion: a comparison of diffusion weighted imaging and histopathology in experimental studyObjective: To discuss the existence and significance of therapeutic window in brain parenchymal lesions on animal model of acute cerebral venous occlusion.Methods: 28 New Zealand white rabbits were randomly divided into 2 groups, including experiment group (n=24) and control group (n=4). DWI was performed at an interval of 1, 3, 6, 12, 24 and 48h after operation which injected CAP in left or right internal jugular vein and by ligation of the bilateral external jugular veins. The specimen was analyzed at different time points by immunohistochemistry.Results:DWI and expression of GFAP, c-fos and NSE can show the process of occurrence and development in brain parenchymal lesions of acute cerebral venous occlusion. The early pathological changes were only detected with DWI (within 1h). The ADC values of the brain parenchymal lesions decreased before 6h. And the ADC values of the brain parenchymal lesions increased subsequently after 12, 24, and 48h. At the 1th hour after operation, the number of GFAP and c-fos immunopositive cells enhanced, the cell bodies enlarged. These changes became obvious after 3h and 6h. No abnormal changes were observed in control group. The process of brain parenchymal lesions in acute cerebral venous occlusion was progressive. The expression of GFAP, c-fos and NSE was consistent with the results of DWI. During the early stage of ADC values's decrease, compensatory mechanism was sufficiently educed in brain cells and the brain lesions had reversibility. And it was possible to get satisfied therapeutic effect through timely treatment.Conclusion: In combination with the expression of GFAP, c-fos and NSE, DWI is accurate in evaluating brain parenchymal lesions. Therapeutic window truly exists in the process of occurrence and development in brain parenchymal lesions of acute cerebral venous occlusion.