基于体素间和体素内弥散指标对首发未服药精神分裂症患者脑白质微观结构的研究

White matter microstructural abnormalities in first-episode medication-free patients with schizophrenia based on inter-voxel and intra-voxel diffusivity metrics

目的采用体素间弥散指标——局部弥散一致性(LDH)值及传统体素内弥散指标探究首发未服药精神分裂症(FESZ)患者脑白质微观结构的异常。方法选择郑州大学第一附属医院精神医学科自2020年1月至2021年12月收治的56例FESZ患者为研究对象, 并同期招募64名健康志愿者作为正常对照组。对所有被试进行磁共振弥散张量成像扫描, 采用FSL及PANDA软件处理得到LDH值、各向异性分数(FA)、平均弥散系数(MD)、轴向弥散系数(AD)和径向弥散系数(RD)值。通过基于纤维束示踪的空间统计(TBSS)方法分析比较2组之间脑白质纤维各个弥散指标的差异。对于组间差异有统计学意义的白质纤维束区域, 采用受试者工作特征曲线(ROC)评价各个弥散指标对FESZ的诊断价值, 采用Spearman偏相关分析检验各个弥散指标与阳性和阴性症状量表(PANSS)评分的相关性。结果与正常对照组相比, FESZ组双侧丘脑前辐射部分体素簇的LDH值明显增加, 差异有统计学意义(P<0.05, FWE校正)。与正常对照组相比, FESZ组右侧下纵束及右侧钩束感兴趣束(TOI)的LDH平均值明显增加, 差异有统计学意义(P<0.05, FDR校正)。在上述纤维束区域, ROC分析显示LDH值均具有诊断效能(P<0.05), 且4个纤维束联合时的LDH值诊断效能最大[曲线下面积(AUC)=0.733, P<0.001]。相关性分析显示FESZ组与正常对照组有显著差异区域的LDH值与PANSS各项评分均不具有相关性(P>0.05)。在FA、MD、AD和RD指标参数图中未发现组间差异有统计学意义的体素簇或TOI(P>0.05)。结论体素间弥散指标LDH值能够检测到传统体素内弥散指标未能发现的FESZ患者脑白质微观结构的代偿性变化。

Objective To investigate the microstructural abnormalities of the white matter in first-episode medication-free patients with schizophrenia(FESZ)based on inter-voxel diffusivity metric local diffusion homogeneity(LDH)and traditional intra-voxel diffusivity metric.Methods A total of 56 FESZ patients admitted to our hospital from January 2020 to December 2021 were selected as research subjects,and 64 healthy volunteers recruited during the same period were selected as healthy controls.All subjects accepted magnetic resonance diffusion tensor imaging,and the LDH,anisotropy fraction(FA),mean diffusivity(MD),axial diffusivity(AD)and radial diffusivity(RD)were obtained by FSL and PANDA software.Tract-based spatial statistics(TBSS)method was employed to analyze and compare the differences in the diffusivity metrics of white matter fibers between the two groups.For white matter fiber tracts with significant inter-group differences,receiver operating characteristic(ROC)curve was used to evaluate the diagnostic value of each diffusivity metric in FESZ,and Spearman partial correlation was used to analyze the relation between each diffusivity metric and positive and negative symptom scale(PANSS)scores.Results As compared with that in the heathy control group,LDH in partial voxel clusters in bilateral anterior thalamic radiation of the FESZ group was statistically increased(P<0.05,FWE correction).As compared with that in the heathy control group,the mean LDH in the tracts of interest(TOI)of the right inferior longitudinal fasciculus and the right uncinate fasciculus in the FESZ group was significantly increased(P<0.05,FDR correction).In the above 4 fasciculi,ROC analysis showed that LDH had diagnostic efficacy(P<0.05),and the diagnostic efficacy of LDH was the highest when the fasciculi structures were combined(AUC=0.733,P<0.001).LDH in white matter fiber tracts with significant inter-group differences had no statistical correlation with PANSS scores(P>0.05).No voxel clusters or TOIs enjoyed statistical differences between groups were noted in the FA,MD,AD and RD parameter maps(P>0.05).Conclusion The inter-voxel diffusivity metric LDH can detect the compensatory changes of white matter microstructure in FESZ patients that could not be detected by traditional intra-voxel diffusivity metric.