扩散峰度成像评价阿尔茨海默病患者脑白质微观结构的改变

目的 采用扩散峰度成像(DKI)探讨阿尔茨海默病(AD)患者脑白质微观结构的改变。方法 对23例AD患者(AD组)和24名健康对照者(HC组)进行常规MR序列及DKI扫描,手动测量额叶、顶叶、枕叶及颞叶皮层下白质、内囊(前、后肢)、外囊、胼胝体(膝、干、压部)的DKI参数,包括扩散峰度(MK)、横向峰度(Ka)、径向峰度(Kr)、平均扩散率(MD)、横向扩散率(Da)、径向扩散率(Dr)及FA值。采用ROC曲线下面积评价各参数值诊断AD的效能。结果 与HC组相比,AD组的顶叶及颞叶皮层下白质、外囊的MK、Ka、Kr值均降低;枕叶皮层下白质的MK、Kr值均降低;内囊前肢、胼胝体膝的MK、Ka值均降低;胼胝体干的MK、Kr值均降低;胼胝体压、内囊后肢的Ka值降低(P均<0.05)。额叶皮层 下白质、内囊前肢、胼胝体干的MD、Da、Dr值均升高;顶叶及颞叶皮层下白质、外囊的MD、 Dr值均升高;胼胝体压部的MD、Da值均升高;内囊后肢、胼胝体膝的MD值均升高;枕叶皮层下白质的Dr值升高(P均<0.05)。额叶、顶叶、枕叶及颞叶皮层下白质、胼胝体干、胼胝体膝、内囊前肢、外囊的FA值减小(P均<0.05)。颞叶皮层下白质Dr值的ROC曲线下面积最大,为0.95。所有部位的MK、Ka、Kr及FA值与MMSE评分均呈正相关;MD、Da及Dr值与MMSE评分呈负相关。结论 DKI参数可反映AD患者脑白质微观结构的改变,颞叶皮层下白质的Dr值是鉴别AD患者与正常人的最佳指标。

Diffusion kurtosis imaging evaluation of brain white matter microstructure changes in Alzheimer disease

Objective To explore the changes of white matter microstructure of Alzheimer disease (AD) with diffusion kurtosis imaging (DKI). Methods Twenty three cases of AD (AD group) and twenty four cases of volunteers (HC group) underwent conventional MR scan and DKI. Bilateral mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr), mean diffusivity (MD), axial diffusivity (Da), radial diffusivity (Dr) and FA values of frontal lobe-white matter (WM), parietal lobe-WM, occipital lobe-WM, temporal lobe-WM, anterior limb of the internal capsule, posterior limb of the internal capsule, external capsule, splenium of the corpus callosum, genu of the corpus callosum, trunk of the corpus callosum were obtained. ROC curve were used to assess the ability of different parameters to diagnosis AD. Results Compared with HC group, the value of MK, Ka and Kr in AD group significantly decreased in parietal lobe-WM, temporal lobe-WM and external capsule; MK and Kr value also decreased in occipital lobe-WM; MK and Ka value decreased in anterior limb of the internal capsule and genu of the corpus callosum; MK and Kr value decreased in trunk of the corpus callosum; Ka value decreased in splenium of the corpus callosum and posterior limb of the internal capsule (all P<0.05). MD, Da and Dr value increased in frontal lobe-WM, anterior limb of the internal capsule and trunk of the corpus callosum; MD and Dr values increased in parietal lobe-WM, temporal lobe-WM and external capsule; MD and Da value increased in splenium of the corpus callosum; MD value increased in posterior limb of the internal capsule and genu of the corpus callosum; Dr value increased in occipital lobe-WM (all P<0.05). FA value in AD group significantly decreased in frontal lobe-WM, parietal lobe-WM, occipital lobe-WM, temporal lobe-WM, trunk of the corpus callosum, genu of the corpus callosum, anterior limb of the internal capsule and external capsule (all P<0.05). The biggest area under ROC curve which was 0.95 was Dr value in the temporal lobe-WM. The MK, Ka, Kr and FA values showed the positive correlation with MMSE score; the negative correlation was presented between MD, Da, Dr and MMSE score in all regions. Conclusion DKI parameters may be more accurate in the assessment of microstructure damage in white matter of AD patients. The Dr value in the temporal lobe-WM can be as the best parameter of differentiation AD from controls.