不同程度阿尔茨海默病PET脑代谢减低的SPM研究

A study on statistical parametric mapping and PET for the metabolism reduction of Alzheimer＇s disease with different severity

目的以统计参数图（SPM）为方法、其输出的脑代谢减低范围大小为指标，探讨不同程度阿尔茨海默病（AD）患者PET显像脑葡萄糖代谢减低区的大小和范围。方法AD组27例，均符合精神障碍诊断和统计工作手册（DSM-Ⅳ-R）中的AD诊断标准，行简易智能量表（MMSE）检查。根据MMSE评分将AD组分为轻度、中度和重度组，每组各9例。对照组9名，均为健康体格检查者。所有受检者静脉注射^18F-脱氧葡萄糖（FDG）后行PET三维脑显像。在Matlab6．5平台上，用SPM2软件对得到的PET图像进行预处理，设P值阈值为0．001，将全部AD患者以及轻、中、重度3个AD患者组分别与对照组进行组间统计分析。结果与对照组比较，AD组于双侧顶叶、颞叶、额叶及扣带回出现代谢减低区，以k值（即满足P值要求的每一“块”异常脑区的像素值）为指标测量，轻度组减低区k值为929，其中额叶减低区k值为174；中度组k值为6743，额叶减低区k值为2712；重度组k值为24678，额叶减低区k值为4981。脑白质及脑内灰质核团未见代谢减低。结论使用SPM，以k值为指标，可对不同程度AD患者脑代谢减低区大小进行评价。随痴呆程度加重，受累脑区范围增加，额叶晚期受累严重。

Objective Along＇with more clinical application of ^18F-fourodeoxyglucose （FDG） PET, statistical parametric mapping （SPM） had attracted a lot of attention in past few years. The purpose of this study was to investigate the regional cerebral glucose metabolism changes in Alzheimer＇s disease （AD） patients with different stages by PET and SPM, according to the k value of the SPM result. Methods Twenty-seven patients with AD according to diagnostic and statistical manual of mental disorders, 4th edition, revised （DSM-Ⅳ-R） and 9 healthy persons as the contrast were examined with three-dimensional （3D） ^18F- FDG PET brain imaging about 40 min pest-injection of 3.7 MBq/kg ^18F-FDG and mini-mental state examination （MMSE） evaluation. The 27 AD patients were divided into 3 groups based on their MMSE scores ： mild group with the score more than or equal to 20 but less than 25, moderate group with the score between10 and 20 （not including 10 and 20）, and severe group with the score less than or equal to 10. All the contrast subjects＇ MMSE scores were more than or equal to 25. On the base of Matlab 6.5, all of the PET images with SPM were normalized and smoothed. A statistical model was established, and the whole AD patients were compared with the contrast group. And then the 3 AD groups were compared with the contrast group respectively. The localization and the k value of the activated region was gotten at last. Results Compared with the healthy group, the most significant metabolic decrease area was in bilateral frontal lobe, parietal lobe, temporal lobe, post cingulate area and precuneus in AD group. The k value of the mild, moderate and severe group was 929, 6743 and 24 678 in order, while the k value of the frontal lobe was 174, 2712 and 4981 in order. Conclusions SPM can be used in evaluating the extension of the regional cerebral glucose metabolism decrease according to the k value. The reduction degree becomes severely along with the progress stages of dementia.