大脑中动脉不同部位急性脑梗死的DKI表现特点

目的 比较DKI各峰度参数与扩散参数早期诊断急性脑梗死的能力,评估大脑中动脉供血区不同部位急性脑梗死后DKI峰度参数的变化特点,探究早期诊断不同部位脑梗死的优势参数图。 方法 回顾性收集单侧大脑中动脉供血区的急性脑梗死病人62例（共84个病灶）,男37例,女25例,年龄43~71岁,平均（57.26±6.27）岁。行DKI扫描并获得轴向扩散率（AD）、平均扩散率（MD）、径向扩散率（RD）、轴向扩散峰度（AK）、平均扩散峰度（MK）、径向扩散峰度（RK）图。按梗死部位将所有病灶分为3组,包括皮质（28个）、皮质下白质（25个）和基底节区（31个）组。采用配对t检验比较各参数值患侧与健侧的差异,采用秩和检验比较各峰度参数变化率（Δ参数值%）的差异,采用单因素方差分析比较3组间各峰度参数健侧绝对值的差异。 结果 与健侧对照区相比,所有梗死灶的扩散参数（AD、MD、RD）值均减低,而峰度参数（AK、MK、RK）值均增高（均P<0.05）。其中,扩散参数的变化率均小于其对应峰度参数的（均P<0.05）。健侧对照区中,皮质下白质区和基底节区的MK、RK值均高于皮质区,而基底节区的RK值也高于皮质下白质区（均P<0.05）。皮质、皮质下白质、基底节区病灶的ΔAK%依次增大（P<0.05）。皮质组的ΔAK%、ΔMK%、ΔRK%的差异无统计学意义（P>0.05）;皮质下白质组的ΔAK%与ΔMK%均大于ΔRK%（均P<0.05）;基底节区组的ΔAK%、ΔMK%、ΔRK%数值呈降序分布（均P<0.05）。 结论 DKI峰度参数较扩散参数更易检出梗死病灶。缺血状态下,皮质下白质及基底节区的组织微结构改变较皮质更为复杂,且AK、MK较RK更有评估不同部位缺血损伤的潜力。对位于皮质、皮质下白质的脑梗死评估,MK图具有优势,而对基底节区的脑梗死早期评估,AK图更具优势。

DKI appearance of acute infarctions at different locations of middle cerebral artery territory

Objective To explore the abilities of DKI kurtosis parameters and diffusion parameters in early diagnosis of acute cerebral infarction, to evaluate the characteristics of DKI kurtosis parameters in different parts of the middle cerebral artery territory after acute cerebral infarction, and to assess the advantages in early diagnosis of cerebral infarction with kurtosis parameter maps. Methods All of 62 patients (37 males and 25 females) with 84 acute infarctions in the middle cerebral artery territory were retrospectively selected, aged from 43 to 71 years old, with an average age of 57.26±6.27 years. DKI sequence was used to obtain the axial diffusion (AD), mean diffusion (MD), radial diffusion (RD), axial kurtosis (AK), mean kurtosis (MK), radial kurtosis (RK) maps. According to the lesions’ sites, all the lesions were divided into three groups: cortex (n=28), subcortical white matter (n=25), and basal ganglia area (n=31). The paired t test was used to compare the difference in each parameter between the affected side and the healthy side, and the rank sum test was used to compare the difference in the change rate (Δparameter%) of each kurtosis parameter. The ANOVA was used to compare the differences in parameter values of the healthy side among the three groups. Results Compared to contra-lateral side, the diffusion parameters AD, MD, and RD were all decreased, while the kurtosis parameters AK, MK, and RK were all increased in the infarcted groups(all P<0.05), and the Δparameter% of each diffusion parameter was less than that of kurtosis parameters (all P<0.05). In the contra-lateral side, the MK and RK values of the subcortical white matter and basal ganglia control regions were higher than the values of the cortical control region, and the RK value of the basal ganglia control region was also higher than that of the subcortical white matter control region (all P<0.05). The ΔAK% vales differed significantly among the cortical, subcortical basal white matter, and basal ganglia lesions, showing the smallest in the cortical lesions, and the highest in the basal ganglia lesions (P<0.05). There was no statistical difference among the ΔAK%, ΔMK%, and ΔRK% in the cortical lesions(P>0.05). Both ΔAK% and ΔMK% were larger than the ΔRK% in the subcortical white matter lesions(P<0.05). Whereas the kurtosis parameters differed significantly among the ΔAK%,ΔMK%, and ΔRK% in the basal ganglia lesions, showing the smallest in the ΔAK%, and highest in the ΔRK% (P<0.05). Conclusions DKI kurtosis parameters are easy to identify infarction lesions than diffusion parameters. During the ischemia, the microstructural changes in the subcortical white matter and basal ganglia are more complicated than in the cortex. Moreover, AK and MK have more advantages to reveal the damage at all different locations than RK. But for the cortical and subcortical white matter infarctions, MK map has more advantages, while AK map has more advantages for the infarctions at the basal ganglia infarctions.