磁共振扩散峰度与张量成像对脑部小血管病皮质脊髓束早期华勒氏变性微观变化的诊断价值

The diagnostic value of MRI diffusion kurtosis imaging and diffusion tensor imaging in early Wallerian degeneration of corticospinal tract in cerebral small-vessel disease

目的探讨磁共振扩散峰度成像(DKI)与扩散张量成像(DTI)对脑部小血管病(CSVD)皮质脊髓束早期华勒氏变性微观变化的诊断价值。方法选择2016年9月至2018年4月于汕头大学医学院第二附属医院神经内科诊断为CSVD,且常规磁共振成像(MRI)提示为腔隙性脑梗死的患者56例,为CSVD组,另选择24例常规MRI无阳性发现者为对照组,均行DKI扫描。CSVD组患者依据T2液体衰减反转恢复(T2-Flair)序列图像显示病灶部位不同,分脑桥组(A1组)、内囊后肢前部组(A2组)、放射冠组(A3组)和皮层下组(A4组),于脑桥、内囊后肢前部、放射冠及皮层下避开梗死灶,在下行纤维束层面双侧看似正常脑白质区测量平均峰度(MK)及DTI参数平均扩散系数(MD)和各向异性分数(FA)值。结果A1、A2、A3、A4组患者脑桥MK值(1.19±0.11,1.18±0.11,1.20±0.10,1.20±0.09),高于对照组脑桥MK值(1.05±0.12),均差异有统计学意义(t=-3.47,-4.10,-5.29,-5.40;均P<0.01)。A1、A3、A4组患者皮层下MK值(1.00±0.08,1.00±0.13,0.99±0.13),高于对照组皮层下MK值(0.92±0.12),均差异有统计学意义(t=-2.12,-2.22,-2.11;均P<0.05)。4个亚组中,MK、MD及FA在4个脑区差异有统计学意义(P<0.05)的脑区数目分别为7个、1个及2个。结论在常规MRI无阳性发现时,DKI检测CSVD患者早期华勒氏变性微观结构变化较DTI敏感。

Objective By analyzing MRI diffusional kurtosis imaging(DKI)and diffusion tensor imaging(DTI)of corticospinal tract(CST)in cerebral small-vessel disease(CSVD),the study compared their diagnostic value to detect the microstructures of early Wallerian degeneration(WD).Methods From September 2016 to April 2018,56 patients diagnosed as CSVD in the Department of Neurology in the Second Affiliated Hospital of Shantou University Medical College,and indicated as lacunar infarction on MRI were selected as CSVD group,and 24 patients without positive findings on MRI were selected as the control group,all of them underwent DKI scan.According to the different lesion sites in MRI T2-Flair,CSVD group was divided into 4 groups,including pons group(A1 group),forepart of posterior limb of internal capsule group(A2 group),corona radiata group(A3 group)and subcortex group(A4 group).The mean kurtosis(MK),mean diffusion(MD)and fractional anisotropic of tensor(FA)were measured on the seemingly normal white matter areas on both sides of the descending fiber bundle in pons,forepart of posterior limb of internal capsule,corona radiata and subcortical area.Results MK values of pons in the A1,A2,A3 and A4 group(1.19±0.11,1.18±0.11,1.20±0.10 and 1.20±0.09,respectively)were higher than those in the control group(1.05±0.12),which showed significant differences(t=-3.47,-4.10,-5.29,-5.40,all P<0.01).MK values of subcortex in the A1,A3 and A4 group(1.00±0.08,1.00±0.13 and 0.99±0.13,respectively)were higher than those in the control group(0.92±0.12),which showed significant differences(t=-2.12,-2.22,-2.11,all P<0.05).In four subgroups,the number of brain regions with statistical significance(P<0.05)in MK,MD and FA,they were 7,1 and 2,respectively.Conclusion DKI is more sensitive than DTI in detecting the microstructure of early WD when there is no positive result in conventional MRI.