基于象素形态测量法分析精神分裂症患者脑白质结构

Voxel-based morphometric analysis on the structure of white matter in schizophrenic patients

目的:应用基于象素的形态测量学方法,分析精神分裂症大脑白质结构与健康人的差异。方法:①分组:精神分裂症组为10名北京大学精神卫生研究所和北京回龙观医院2005-04/2006-03收治,符合ICD-10、DSM-Ⅳ精神分裂症偏执型诊断标准的患者;健康对照组是年龄、性别和受教育程度与精神分裂症组相匹配的健康志愿者10名。所有受试者均签署知情同意书。②检测方法和参数:采用西门子1.5TSonataMRI成像系统,对所有受试者行全脑扫描,解剖图像采用T1加权序列矢状成像(MPRAGE),共采集96层。TR=1900ms,TE=3.93ms,flip15°,FOV=220mm×220mm,图像分辨率0.43mm×0.43mm×1.70mm。③数据处理:在SPM5平台上,使用VBM5工具箱进行技术进行处理。采用MNI的标准脑图谱配准,配准后图像分辨率2mm×2mm×2mm;采用HMRF算法进行组织分割,目标是测量白质密度,故未经体积调制;用12mm半高全宽高斯核对脑白质密度图进行平滑;然后采用SPM的组分析方法,对两组进行成组t检验,t>3.61,P<0.001(未校正)、相连象素大于20个的信号变化脑区视为有差异脑区。结果:20名受试者均完成测试进入结果分析。精神分裂症组密度低于对照组的区域有双侧颞下回、双侧额下回、双侧梭状回、左侧海马旁回、左侧胼胝体、左侧丘脑、左侧顶下叶、左侧楔前叶、右侧额中回、右侧颞中回,没有发现精神分裂症组白质密度高于对照组的区域。结论:①精神分裂症患者白质缺陷部位广泛。结合同一研究对象的功能磁共振成像研究结果提示左侧丘脑和双侧梭状回与精神分裂症有密切关系。②基于象素的形态测量学的方法有快速和全自动的特点,具有不受分析人员主观影响等优点。

AIM： To assess the difference in the structure of brain white matter between schizophrenic patients and healthy controls by using voxel-based morphometry （VBM）. METHODS： ①Grouping： Ten schizophrenic patients （according to ICD-10 and DSM-Ⅳ） were enrolled from the Institute of Mental Health, Peking University and Beijing Huilongguan Hospital between April 2005 and March 2006. Moreover, ten healthy volunteers who matched well in age, gender and educational level were taken as controls, and all the subjects were signed the informed consents.②Detection method and parameters： All the subjects were scanned by Siemens Sonata 1.5T MRI system. A series of 96 contiguous sagittal images were acquired using a magnetization prepared rapid gradient echo（MPRAGE） sequence with the following parameters： TR=1 900 ms; TE=3.93 ms; 15° flip angle; field of view （FOV）= 220 mm×220 mm; voxel dimensions were 0.43 mm×0.43 mm×1.70 mm.③Data process： The data were processed by the VBM5 toolbox on the latest version of SPM5. All primary images were registered to the ICBM152 template （Montreal Neurological Institute）. The spatially normalized images were resliced with a final voxel size of 2 mm× 2 mm ×2 mm; The VBM5 toolbox extended the core segmentation algorithm by the Hidden Markov Random Field （HMRF）. The images of no modulation were adopted to measure the density of white matter; The segmented images were smoothed using a 12-mm Full Width at Half Maximization （FWHM） isotropic Gaussian kernel. Statistical analyses were carried out on specify 2^nd -level of SPM5. The resulting set of voxel values for this contrast constituted a Statistical Parametric Map of the t test. The threshold at P 〈 0.001（not corrected, t 〉 3.61） and threshold extended 20 voxels, were taken as different encephalic region. RESULTS： All 20 subjects were involved in the result analysis. Compared to healthy controls, the schizophrenic patients significantly decreased the density of white matter, which was found in the bilateral inferior temporal gyrus, bilateral inferior frontal gyrus, bilateral fusiform gyrus, left parahippocampus, left corpus callosum, left thalamus, left inferior parietal Iobule, left precuneus, right middle frontal gyrus, and right middle temporal gyros. CONCLUSION： ①The deficit of white matter is widespread in brain regions of schizophrenic patients. Combined with result of functional MRI on same patients and healthy controls in another study, it is suggested that left thalamus and bilateral fusiform gyrus have a close relationship with schizophrenia. ②VBM is the fast and automatic approach and has the advantage of not being affected by researchers.