【摘要】 目的探讨缺血性脑梗死的扩散各向异性(FA)的时间演变规律及其临床应用价值。资料与方法回顾性分析超急性期到慢性期的不同发病时间的149次脑梗死磁共振扩散张量成像资料,计算各期病灶及其对侧镜像区的平均FA,比较病灶和对侧的FA值的变化规律。结果发病6h内、7～12h和13～24h以内的脑梗死病灶FA值和对侧比较无显著性差异,24h后则显著低于对侧(P<0.01),并随发病时间进行性下降。发病24h内病灶FA值变化有三种模式:升高、降低和维持不变,且病灶FA高于或等于对侧的情况也主要见于发病24h内。结论脑梗死病灶的FA值在发病24h内无显著变化,24h后迅速下降,并持续到慢性晚期;24h是FA值的时间转变点,可能反映了细胞毒性水肿向血管源性水肿的转变。更多还原

【Abstract】 Objective To investigate the clinical value and temporal evolution of fractional anisotropy(FA)in human stroke.Materials and Methods We analyzed the full diffusion tensor MRI studies of stroke at varying time points from hyperacute to chronic stage in 149 cases retrospectively.Mean value of FA were measured in the lesions and the normal contralateral region at each time point and the ratio of lesions to control regions of interest were calculated.Results Mean FA of infarctions for studies performed within 6,7-12,and 13-24 hours were not significantly different from that of the contralateral side(P<0.01),while it was significantly decreased after 24 hours at all different time pointes.FA character is especially complex within 24 hours after stroke onset.There were three patterns of FA characters in this period:elevated,unchanged and decreased.The elevated or unchanged patterns were mainly found within 24 hours after initial stroke onset(χ2=38.588,P<0.001).Conclusion Two phases in the time course of relative FA changes in human stroke can be found:slightly elevated or unchanged within 24 hours and quickly decreased after 24 hours and further reduced in chronic stage.24 hour can be a time-point for FA transition.Elevated or unchanged FA after stroke onset mainly distributed in 24 hours,while is rare after 24 hours.Heterogeneity of FA changes in 24 hours may indicate the heterogeneity of stroke evolution between individuals and hence may be useful in selecting an appropriate intervention.更多还原