摘要
目的探讨导致阿尔茨海默病（AD）患者DTI改变的生化代谢基础。方法选取15例轻度AD患者、20例中重度AD患者以及20名年龄相匹配的正常老年志愿者进行DTI和^1H—MRS检查。测量双侧扣带回后部皮质区N-乙酰天冬氨酸（NAA）／肌酸（Cr）、胆碱（Cho）／Cr、肌醇（mI）／Cr的相对值。DTI采用EPI序列，生成平均扩散系数（MD）、部分各向异性（FA）参数图。选择与MRS同一层面的DTI参数图将RIO分别置于双侧扣带束后部区域，测量MD及FA值。组间比较采用Mann—Whitney U非参数法分析，相关分析采用偏相关分析法控制年龄因素的差异。结果正常组、轻度及中蕈度AD组间NAA呈逐步降低的趋势；mI／Cr升高，在轻度AD组（0．68±0．12）与对照组（0．61±0．07）差异有统计学意义（Z=2．911，P〈0．01）。轻度AD患者左侧扣带束FA值（0．517±0．058）较对照组（0．549±0．0567）明显降低（Z=2．01g，P〈0．05），中重度组较轻度AD组右侧扣带束FA值下降，同时MD值增高[轻度组：FA0．517±0．059，MD（0．726±0．041）×10^-3mm^2／s；中重度组：FA0．432±0．073，MD（0．761±0．057）×10^-3mm^2／s，Z值分别为3．216、1．970，P值均〈0．05]。轻度AD组左侧扣带束FA值与mI／Cr值呈正相关（r=0．586，P〈0．05）。中重度组右侧扣带束MD值与NAA／Cr呈负相关性（r=-0．505，P〈0．05）。结论AD患者扣带束后部的白质纤维束完整性降低存在区域性和时域性差异，提示AD患者的白质损害在不同阶段存在不同的主导因素。联合应用MRS和DTI的方法有助于了解AD患者病理进程改变。
Objective To compare ^1HMRS and DTI findings of Alzheimer disease （AD） patients and normal elderly controls. Methods Fifteen mild AD patients, 20 moderate to severe AD patients and 20 aging controlled normal subjects （CN） were recruited. MRS imaging and DTI were performed on a 1.5 T MRI scanner. A ROI was positioned in the posterior part of the eingulate. MRS data were processed and the metabolite ratios were estimated, including the ratios of NAA/Cr, Cho/Cr, ml/Cr. Comparing with the axial MRS location, we chose the same level to posit the ROIs on both sides of the posterior cingulated fibers on fractional anisotropy map （FA） and mean diffusivity map （MD）. Mean spectroscopy data and DTI values for each groups were analysed with Mann-Whitney U non parametric test. Correlations between MRS and DTI values for AD groups were estimated using partial correlations test controlling for the age related bias. Results Compared to normal aging groups, mild AD group showed a significantly lower FA value in the left side of posterior cingulum bundle （0. 549 ±0. 056 vs 0. 517 ±0. 058 ,Z =2. 014,P 〈0. 05）. Whereas, moderate to severe group versus mild AD group revealed significantly elevated MD value and a decrease in FA value in the right side of posterior cingulate （ FA 0. 517 ± 0. 059 vs 0. 432 ± 0. 073, Z = 3. 216, P 〈 0. 01 ; MD （0.726±0.041） × 10^-3 mm^2/s vs （0.761 ±0.057） × 10^-3 mm^2/s,Z = 1.970,P 〈0.05） . Obvious increasing mI/Cr ratio was found in mild AD group（0. 61 ±0. 07 vs 0. 68 ±0. 12,Z =2. 911 ,P 〈0. 01 ）.NAA/Cr ratio showed gradually decrease in AD groups. Partial correlations analysis revealed a positive correlation between mI/Cr ratio and left posterior cingulated FA value in mild AD group （ r = 0. 586, P 〈 0. 05 ） and negative correlation between NAA/Cr and MD value in the right side of posterior cingulated region （ r = - 0. 505, P 〈 0. 05）. Conclusions These findings suggested that there were different regional and temporal pattern in different course of AD disease, resulting from axonal loss or gliosis. Combining MRS with DTI alternations could be a better potential indicator and could better explain the pathological changes in AD progression.
出处
《中华放射学杂志》
CAS
CSCD
北大核心
2009年第5期495-499,共5页
Chinese Journal of Radiology
关键词
阿尔茨海默病
磁共振成像
磁共振波谱学
Alzheimer disease
Magnetic resonance imaging
Magnetic resonance spectroscopy
作者简介
通信作者：陈克敏，Email：keminchenrj@yahoo．com.cn
