中文摘要：

目的探讨急性脑梗死在R2＇图中的表现,并与DWI比较,探讨其在判断脑缺血半暗带中的价值。方法对14例发病时间为6～22h[平均（16.73±4.65）h]的急性脑梗死患者于就诊当日和发病后7～20天分别进行MR检查。将首次检查中的DWI高信号区定义为初始病灶面积（L0）,第二次复查的T2WI或T2-FLAIR图像上病灶面积定义为最终梗死面积,后者小于L0的部分为组织存活区（ST）,大于L0的部分为病灶扩大区（LG）。对同一患者不同检查时间病灶形态和面积进行比较。结果初次检查异常信号的面积可分为3种：①4例R2＇图病灶面积〉DWI高信号区面积,最终梗死面积与R2＇图异常信号区面积相同。R2＇图病灶为稍高信号,LG区R2＇信号升高的程度最大,周围区次之,L0区最小;复查时R2＇图病灶变为低信号。②6例R2＇图病灶面积=DWI高信号区面积,最终梗死面积无显著变化。③4例R2＇图病灶面积〈DWI高信号区面积,R2＇图病灶中心为低信号,边缘为稍高信号,在外围为等信号,呈内低外高分层状表现,最终梗死灶的面积与初次R2＇上低信号区的面积相似。结论①发病24h内,脑梗死灶在R2＇图的3种情况分别具有不同的演变过程;②相对于传统MR成像序列,R2＇在判断梗死核心和半暗带方面更精确。

英文摘要：

Objective To explore the characteristics of R 2 ’in acute cerebral infarction,and to estimate its value on judging the infarction core and ischemic penumbra（IP） compared with DWI.Methods Totally 14patients with acute cerebral infarction within 24hof symptom onset were analyzed.The mean time from symptom onset to hospital was（16.73±4.65） h（6 — 22h）.All patients underwent MR on the first day and 7 — 20days after treatment.The lesions on DWI on the first day were defined as initial lesion（L0）,the final infarct size was defined on T2WI or T2-FLAIR in 7 — 20days after treatment.Surviving tissue（ST） was final infarct area of less than L0part,and lesion growth（LG） was final infarct area of larger than L0part.The lesion shape was manually drawn in each picture and then compared with each other.Results Three conditions were observed about the area of abnormal signal intensity on R2’and DWI in the initial inspection ： ①Area of lesions of 4patients in R 2 ’map were larger than that in DWI.The final infarct size was similar to the area of abnormal signal intensity on R2’.The initial lesion showed slightly high signal intensity on R2’,whereas LG was higher than L0and surrounding tissue.②Area of lesions of 6patients in R2’map were equal to that in DWI.There was no significant changes in the final infarct size.③Area of lesions of 4patients in R 2 ’map were less than that in DWI.Center of lesions were low signal intensity on R2’map surrounded by high signal intensity.The final infarct size was similar to that of low signal intensity on R2’of initial inspection.Conclusion ①Within 24hsince symptom onset,cerebral infarct lesion can be divided into three conditions,which have different developing processes respectively.②R2’imaging is more accurate in depicting infarct core and ischemic penumbra than conventional MRI.