Department of Radiology, School of Medicine, University of Crete, Heraklion, Crete, Greece.
Department of Psychiatry, School of Medicine, University of Crete, Heraklion, Crete, Greece.
J Magn Reson Imaging. 2018 May;47(5):1359-1372. doi: 10.1002/jmri.25849. Epub 2017 Aug 31.
Existing indices of white matter integrity such as fractional anisotropy and magnetization transfer ratio may not provide optimal specificity to myelin content. In contrast, myelin water fraction (MWF) derived from the multiecho T relaxation time technique may serve as a more direct measure of myelin content.
PURPOSE/HYPOTHESIS: The goal of the present study was to identify markers of regional demyelination in patients with probable Alzheimer's disease (AD) and mild cognitive impairment (MCI) in relation to age and severity of neuropsychiatric impairment.
The sample included patients diagnosed with probable AD (n = 25) or MCI (n = 43), and cognitively intact elderly controls (n = 33).
FIELD STRENGTH/SEQUENCE ASSESSMENT: Long T , short T , and MWF values were measured with a 1.5T scanner in periventricular and deep normal-appearing white matter (NAWM), serving as indices of intra/extracellular water content and myelin content. A comprehensive neuropsychological and neuropsychiatric assessment was administered to all participants.
STATISTICAL TESTS, RESULTS: AD patients displayed higher age-adjusted long and short T values and reduced MWF values in left temporal/parietal and bilateral periventricular NAWM than controls and MCI patients (P < 0.004; one-way analysis of covariance [ANCOVA] tests). Short T /MWF values in temporal, frontal, and periventricular NAWM of controls and/or MCI patients were significantly associated with episodic and semantic memory performance and depressive symptomatology (P < 0.004; partial correlation indices). The impact of age on memory performance was significantly (P < 0.01; mediated linear regression analyses) mediated by age-related changes in short T and MWF values in these regions.
Age-related demyelination is associated with memory impairment (especially in prodromal dementia states) and symptoms of depression in an anatomically specific manner.
1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1359-1372.
现有的白质完整性指标，如各向异性分数和磁化传递率，可能无法提供髓鞘含量的最佳特异性。相比之下，多回波 T 弛豫时间技术得出的髓鞘水分数（MWF）可能是髓鞘含量的更直接测量指标。
目的/假设：本研究的目的是确定与年龄和神经精神损伤严重程度相关的，在疑似阿尔茨海默病（AD）和轻度认知障碍（MCI）患者中的区域性脱髓鞘标志物。
该样本包括被诊断为疑似 AD（n=25）或 MCI（n=43）的患者，以及认知正常的老年对照组（n=33）。
场强/序列评估：使用 1.5T 扫描仪测量脑室周围和深部正常表现的白质（NAWM）中的长 T 、短 T 和 MWF 值，作为细胞内外水含量和髓鞘含量的指标。对所有参与者进行了全面的神经心理学和神经精神病学评估。
统计检验、结果：与对照组和 MCI 患者相比，AD 患者的年龄调整后长 T 和短 T 值更高，左侧颞顶和双侧脑室周围 NAWM 的 MWF 值更低（P＜0.004；单因素协方差分析[ANCOVA]检验）。对照组和/或 MCI 患者的颞叶、额叶和脑室周围 NAWM 的短 T /MWF 值与情景记忆和语义记忆表现以及抑郁症状显著相关（P＜0.004；部分相关指数）。年龄对记忆表现的影响（P＜0.01；中介线性回归分析）在这些区域通过与年龄相关的短 T 和 MWF 值变化而产生。
与年龄相关的脱髓鞘与记忆障碍（尤其是在前驱痴呆状态下）和抑郁症状以解剖学特异性的方式相关。
1 技术功效：阶段 3 J. Magn. Reson. Imaging 2018;47:1359-1372.
