To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 pL shRNA- aquapo...To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 pL shRNA- aquaporin-4 （control group） or siRNA- aquaporin-4 solution （1：800） （RNA interference group） into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25- 6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5 4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson＇s correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient （r = -0.806, P 〈 0.01）. These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracelfular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.展开更多
Objective:To analyze characters of magnetic resonance spectroscopy(MRS) and diffusion tensor imaging(DTI) in the diagnosis of mild trauma brain injuries(MTBI) in frontal lobe and to compare with conventional magnetic ...Objective:To analyze characters of magnetic resonance spectroscopy(MRS) and diffusion tensor imaging(DTI) in the diagnosis of mild trauma brain injuries(MTBI) in frontal lobe and to compare with conventional magnetic resonance imaging(MRI).Methods:A total of 21 patients were selected,who all aged 12-51 years old and had injury within 24 hours.Computer tomography (CT) and the Glasgow Coma Scale were used to evaluate the degree of injury.All patients were diagnosed as MTBI,and 19 had conventional MRI,MRS and DTI.The major parameters of MRS were Probe-P sequence,TE= 144 or 35 ms,and both single voxel spectrum and chemical shift imging were included.The major parameters of DTI were diffusion directions =15,b value = 1000 s/mm^2. Frational anisotropic(FA) map and average ADC map were obtained to evaluate DTI result. Positive deletion ratio was observed and the imaging changes were compared between injured side and normal side.Results:All 21 patients had CT scan and Glasgow scale.A total of 19 patients had conventional MRI.DTI and MRS.Results of CT and conventional MRI showed no significant abnormality in lobe,and Glasgow scale showed mild type.MRS result showed significant decrease in N-acetyl aspartate(NAA) and NAA/creatine(Cr) in 13 cases(68.4%) (P【0.001),and increase in lactic acid(Lac) in 7 cases(36.8%).FA mapping of the frontal lobe displayed significant changes in 7 cases(36.8%),with 5 out of the 7 cases having increase in FA value.And there was no significant difference in average ADC.Conclusions:MRS and DTI might be more sensible than other methods,such as CT and conventional MRI in diagnosis of MTBI.The particular changes were reduced NAA and increased Lac for MRS.and increased FA values for DTI.展开更多
In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） follow...In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） following cerebral infarction. The pathological changes were divided into three phases： early cerebral infarction, middle cerebral infarction, and late cerebral infarction. In the early cerebral infarction phase （less than 2 hours post-infarction）, there was evidence of intracellular edema, which improved after reperfusion. This improvement was defined as the ischemic penumbra. In this phase, a high DWI signal and a low apparent diffusion coefficient were observed in the right basal ganglia region. By contrast, there were no abnormal T2WI and T2FLAIR signals. For the middle cerebral infarction phase （2-4 hours post-infarction）, a mixed edema was observed. After reperfusion, there was a mild improvement in cell edema, while the angioedema became more serious. A high DWI signal and a low apparent diffusion coefficient signal were observed, and some rats showed high T2WI and T2FLAIR signals. For the late cerebral infarction phase （4-6 hours post-infarction）, significant angioedema was visible in the infarction site. After reperfusion, there was a significant increase in angioedema, while there was evidence of hemorrhage and necrosis. A mixed signal was observed on DWI, while a high apparent diffusion coefficient signal, a high T2WI signal, and a high T2FLAIR signal were also observed. All 86 cerebral infarction patients were subjected to T2WI, T2FLAIR, and DWI. MRI results of clinic data similar to the early infarction phase of animal experiments were found in 51 patients, for which 10 patients （10/51） had an onset time greater than 6 hours. A total of 35 patients had MRI results similar to the middle and late infarction phase of animal experiments, of which eight patients （8/35） had an onset time less than 6 hours. These data suggest that defining the ＂therapeutic time window＂ as the time 6 hours after infarction may not be suitable for all patients. Integrated application of MRI sequences including T2WI, T2FLAIR, DW-MRI, and apparent diffusion coefficient mapping should be used to examine the ischemic penumbra, which may provide valuable information for identifying the ＂therapeutic time window＂.展开更多
基金supported by the National Natural Science Foundation of China, No. 30960399, 81160181
文摘To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 pL shRNA- aquaporin-4 （control group） or siRNA- aquaporin-4 solution （1：800） （RNA interference group） into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25- 6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5 4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson＇s correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient （r = -0.806, P 〈 0.01）. These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracelfular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.
基金supported by the Science Foundation of Haikou Ilealth Bureau(2010-SWY-13-058)Haikou Science Technology Information Bureu(2009-049-1)
文摘Objective:To analyze characters of magnetic resonance spectroscopy(MRS) and diffusion tensor imaging(DTI) in the diagnosis of mild trauma brain injuries(MTBI) in frontal lobe and to compare with conventional magnetic resonance imaging(MRI).Methods:A total of 21 patients were selected,who all aged 12-51 years old and had injury within 24 hours.Computer tomography (CT) and the Glasgow Coma Scale were used to evaluate the degree of injury.All patients were diagnosed as MTBI,and 19 had conventional MRI,MRS and DTI.The major parameters of MRS were Probe-P sequence,TE= 144 or 35 ms,and both single voxel spectrum and chemical shift imging were included.The major parameters of DTI were diffusion directions =15,b value = 1000 s/mm^2. Frational anisotropic(FA) map and average ADC map were obtained to evaluate DTI result. Positive deletion ratio was observed and the imaging changes were compared between injured side and normal side.Results:All 21 patients had CT scan and Glasgow scale.A total of 19 patients had conventional MRI.DTI and MRS.Results of CT and conventional MRI showed no significant abnormality in lobe,and Glasgow scale showed mild type.MRS result showed significant decrease in N-acetyl aspartate(NAA) and NAA/creatine(Cr) in 13 cases(68.4%) (P【0.001),and increase in lactic acid(Lac) in 7 cases(36.8%).FA mapping of the frontal lobe displayed significant changes in 7 cases(36.8%),with 5 out of the 7 cases having increase in FA value.And there was no significant difference in average ADC.Conclusions:MRS and DTI might be more sensible than other methods,such as CT and conventional MRI in diagnosis of MTBI.The particular changes were reduced NAA and increased Lac for MRS.and increased FA values for DTI.
基金supported by the National Natural Science Foundation of China,No.30960399,and No.81160181
文摘In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） following cerebral infarction. The pathological changes were divided into three phases： early cerebral infarction, middle cerebral infarction, and late cerebral infarction. In the early cerebral infarction phase （less than 2 hours post-infarction）, there was evidence of intracellular edema, which improved after reperfusion. This improvement was defined as the ischemic penumbra. In this phase, a high DWI signal and a low apparent diffusion coefficient were observed in the right basal ganglia region. By contrast, there were no abnormal T2WI and T2FLAIR signals. For the middle cerebral infarction phase （2-4 hours post-infarction）, a mixed edema was observed. After reperfusion, there was a mild improvement in cell edema, while the angioedema became more serious. A high DWI signal and a low apparent diffusion coefficient signal were observed, and some rats showed high T2WI and T2FLAIR signals. For the late cerebral infarction phase （4-6 hours post-infarction）, significant angioedema was visible in the infarction site. After reperfusion, there was a significant increase in angioedema, while there was evidence of hemorrhage and necrosis. A mixed signal was observed on DWI, while a high apparent diffusion coefficient signal, a high T2WI signal, and a high T2FLAIR signal were also observed. All 86 cerebral infarction patients were subjected to T2WI, T2FLAIR, and DWI. MRI results of clinic data similar to the early infarction phase of animal experiments were found in 51 patients, for which 10 patients （10/51） had an onset time greater than 6 hours. A total of 35 patients had MRI results similar to the middle and late infarction phase of animal experiments, of which eight patients （8/35） had an onset time less than 6 hours. These data suggest that defining the ＂therapeutic time window＂ as the time 6 hours after infarction may not be suitable for all patients. Integrated application of MRI sequences including T2WI, T2FLAIR, DW-MRI, and apparent diffusion coefficient mapping should be used to examine the ischemic penumbra, which may provide valuable information for identifying the ＂therapeutic time window＂.
