【作者】 刘珍友；

【导师】 张云亭； 张敬；

【作者基本信息】 天津医科大学 ， 影像医学与核医学， 2010， 博士

【摘要】 一.R2’和T2’成像随年龄变化规律目的了解在3.0T磁共振上R2、T2、R2*、T2*、R2’、T2’各个年龄组的正常值,探讨正常人上述各值随年龄变化的规律；了解R2、T2、R2*、T2*、R2’、T2’两侧大脑半球和男女性别之间有无差异。材料和方法共59位志愿者参与本研究,年龄25～76岁,平均49.73±14.65岁。其中男28人,平均年龄50.25±15.07岁；女31人,平均年龄49.26±14.51岁。将所有志愿者以10岁为一个年龄组,共分为6组,分别为21～30岁10例,31～40岁9例,41～50岁12例,51～60岁11例,61～70岁10例和70岁以上组7例。半卵圆中心和脑室周围高信号按照轻重程度分为0-Ⅵ级,作为脑白质稀疏的程度。将扫描得到的T2map和T2*map原始图像转到ADW4.3工作站,处理后得到R2、T2、R2*、T2*、R2’、T2’图像。在上述各序列图像中测量双侧额叶白质、枕叶白质、皮层下白质、尾状核头、壳核、苍白球、丘脑的值并记录进行统计分析。结果总体上脑内中央灰质核团R2、R2*、R2’所测的数值与年龄均呈正相关,而T2、T2*、T2’所测的数值与年龄均呈负相关。总体脑白质除了R2和T2分别与年龄呈负相关和正相关外,其余R2*、T2*、R2’、T2’与年龄均无相关性。尾状核、壳核R2值左侧稍高于右侧(t=-3.607～-3.749,P=0.037～0.000)；额叶及枕叶白质T2(t=11.16～3.659,P=0.000～0.001)值均显示左侧稍低于右侧。男女性别间各序列均没有统计学差异(P>0.05)。T2、T2*弛豫时间随脑白质稀疏等级增高而增加,与其呈正相关(r=0.270～0.276,P<0.05),而T2’则与脑白质稀疏没有相关性(P>0.05)。结论①脑内中央灰质随年龄增加,T2、T2*、T2’值逐渐降低,而R2、R2*、R2’值逐渐升高；②脑白质区随年龄增加,T2值逐渐升高,而R2值逐渐降低；R2’和T2’值与年龄没有相关性；③尾状核、壳核R2值左侧稍高于右侧；额叶及枕叶白质T2值左侧低于右侧；④男女性别间各个部位R2、T2、R2*、T2*、R2’、T2’值均无统计学差异；⑤T2’值与脑白质稀疏没有相关性。二.BOLD成像在急性脑梗死中的初步临床应用目的了解R2’和T2’在急性脑梗死中的表现,并与MR／-DWI比较,探讨其在判断脑缺血半暗带中的价值。材料和方法14例发病时间<24h的急性缺血性脑中风患者,其中男8例,女6例,年龄44～75岁,平均56.36±9.28岁。发病时间6～22h,平均16.73±4.65h。患者于就诊首日和发病后7～20天分别进行MRI检查。首次检查DWI高信号区定义为初始病灶面积(LO),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。最终梗死面积小于第一次DWI面积的部分定义为组织存活区(ST),最终梗死面积大于第一次DWI面积者为病灶扩大区(LG)。扫描序列包括横轴位T1WI、T2WI、DWI、T2-FLAIR、T2map、T2*map、3D-TOF MRA、FAIR。总的检查时间约为20min。将所得图像在ADW4.3工作站Functool软件中采用图像重叠的方法,分别手动绘出每个序列图像的病灶形态,并进行比较。结果根据影像表现,初次检查时DWI和R2’图像上异常信号的面积大小可分为三种情况：①R2’>DWI,共4例；②R2’=DWI,共6例；③R2’<DWI,共4例。在第一种情况下,病灶区R2’为稍高信号,LG区R2’信号升高的程度最大,周围区次之,中央区最小。复查时R2’变为低信号,最终梗死面积与R2’异常信号区面积相同。第二种情况,初次检查时R2’上异常信号区的面积与DWI上高信号区的面积相当,最终梗死面积无显著变化。第三种情况下,初次检查时R2’异常信号区的面积小于DWI上高信号区的面积。在R2’图上,病灶中间为低信号,边缘为高信号,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在发病24小时内,脑内梗死灶在BOLD图像上可以分为三种情况：R2’>DWI、R2’=DWI和R2’<DWI,它们分别具有不同的演变过程；②相对于传统MRI成像序列,BOLD图像可以更精确的显示最终梗死面积,明确的判断出梗死核心和半暗带；③利用BOLD图像,可以显示部分患者位于DWI高信号区内的半暗带组织；④在判断缺血核心和半暗带方面,R2’和T2’具有相同的作用。更多还原

【Abstract】 PartⅠ:Age-dependent normal values of R2’and T2’in brain parenchyma on 3.0T MRIObjective In our study, R2, T2, R2*, T2*, R2’ and T2’values of brain parenchyma were determined with 3.0T MRI in healthy subjects to determine standard values and to investigate the age-related pattern of them. The differences of two cerebral hemispheres and gender of the above values were also studied.Material and methods Total 59 healthy volunteers ranged 25-76 years of old (mean age 49.73±14.65 years) took part in our study.28 male volunteers with the mean age 50.25±15.07 years and 31 female with the mean age 49.26±14.51 years were studied.59 volunteers were divided into 6 groups according to each group 10 years. Leukoaraiosis was considered a regular aging process and was graded 0-Ⅵcorresponding to semioval center and periventricular high signal intensity on T2WI. The raw date including T2map and T2*map were transferred to ADW4.3 workstation. After calculation of R2, T2, R2*, T2*, R2’,T2’maps, the values of deep gray matter (head of caudate nucleus, putamen, globus pallidus, thalamus) and white matter (frontal white matter, occipital white matter and subcortical white matter) were measured in distinct regions of interest (ROI).Results In general, there was a positive correlation between age and R2, R2* and R2’values in deep gray matter. Correspondingly, there was a negative correlation between age and T2, T2* and T2’values in gray matter. In general, there was no correlation between age and R2*,T2*, R2’, T2’values except R2 and T2 which was respectively negative and positive correlation with age in white matter. R2 values of left side caudate nucleus and putamen was slightly higher than that of right side (t=11.16～3.659, P=0.000～0.001). T2 values of left frontal and occipital white matter were lower than that of right side (t=11.16～3.659, P=0.000-0.001).There was no statistic differences between male and female in all sequences (P>0.05). T2 and T2* values increased corresponding to the high degree of leukoaraiosis. Contrast to T2 and T2*, there was no association of T2’values with the degree of leukoaraiosis.Conclusion①The increase of T2, T2* and T2’values but decrease of R2, R2* and R2’values correlate with the progress of the brain aging in central gray matter.②In general, the increase of T2 values and decrease of R2 values in white matter correlate with the progress of brain aging. There is no correlation between R2’, T2’values and aging.③R2 values of left side is higher than that of right side in both gray matter(head of caudate nucleus, putamen)and white matter(frontal white matter and occipital white matter) but the T2 values is lower.④There is no statistic differences between male and female in R2, T2, R2*, T2*, R2’and T2’sequences.⑤There is no association of T2’values with the degree of leukoaraiosis.PartⅡ:The early clinical use of BOLD imaging in acute ischemic strokeObjective To show the features of R2’and T2’in acute ischemic stroke. Compare them with diffusion weighted imaging (DWI) to estimate the value of them in judging the infarction core and ischemic penumbra (IP)Material and methods 14 patients (male 8 and female 6) with acute ischemic stroke within 24 hours of symptom onset underwent MRI examination. The mean age was 56.36±9.28 years old, with a rang of 44～75 years. The mean time from symptom onset to hospital was 16.73±4.65 hours (6-22 hours). The high signal intensity on DWI in first MRI examination was difined L0. Follow-up were performed on day 7 to 20 days. The final infarct size was defined on T2WI or T2-FLAIR imaging in follow 7-20 days. Lesion growth (LG)from day 1 to day 7-20 was derived by subtracting day 1 from day 7-20, and surviving tissue (ST)was calculated by subtracting day 7-20 from day 1. The MRI sequences include T1WI, T2WI, DWI, T2-FLAIR, T2map, T2*map and 3D-TOF MRA. The total time of examination was 20 minutes. Functool software in ADW4.3 workstation was used to overlap the pictures. The lesion shape were manually drawn in each picture and then compared them eachother.Results Three conditions were defined according to the area of abnormal signal intensity on DWI and R2’in first MRI:①R2’>DWI,4 cases;②R2’=DWI,6 cases; ③R2’<DWI,4 cases. For the first condition, the lesion showed slightly high signal intensity on R2’.The quantitative measurement demonstrated that the LG was highest in R2’values and the secondary was surrounding area, and the lowest was LO. In follow-up MRI examination, the final infarct size was similar to the area of abnormal signal intensity on R2’. In second condition, the area of lesions on DWI and R2’was equal on both day 1 and day 7-20. For the third condition, the low signal intensity was located in central area of lesions surrounded by high signal intensity on R2’. The final infarct size was similar with the area of low signal intensity on first R2’.Conclusion①Within 24 hours since symptom onset, cerebral ischemic lesion can be divided into three conditions according to BOLD images:R2’>DWI, R2’=DWI and R2’<DWI, which have different develop process respectively;②BOLD imaging can show final infarct size and demonstrate ischemic core and ischemic penumbra with more accuracy than conventional MRI;③Ischemic penumbra within high signal intensity on DWI can be show by BOLD imaging in some patients.④R2’and T2’have equal effect in judging ischemic core and ischemic penumbra.更多还原