Benitez Andreana, Fieremans Els, Jensen Jens H, Falangola Maria F, Tabesh Ali, Ferris Steven H, Helpern Joseph A
Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC 29425, USA ; Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC 29425, USA.
Neuroimage Clin. 2013 Nov 9;4:64-71. doi: 10.1016/j.nicl.2013.11.001. eCollection 2014.
Post-mortem and imaging studies have observed that white matter (WM) degenerates in a pattern inverse to myelin development, suggesting preferential regional vulnerabilities influencing cognitive decline in AD. This study applied novel WM tract integrity (WMTI) metrics derived from diffusional kurtosis imaging (DKI) to examine WM tissue properties in AD within this framework. Using data from amnestic mild cognitive impairment (aMCI, n = 12), AD (n = 14), and normal control (NC; n = 15) subjects, mixed models revealed interaction effects: specific WMTI metrics of axonal density and myelin integrity (i.e. axonal water fraction, radial extra-axonal diffusivity) in late-myelinating tracts (i.e. superior and inferior longitudinal fasciculi) changed in the course of disease, but were stable in the initial stages for early-myelinating tracts (i.e. posterior limb of the internal capsule, cerebral peduncles). WMTI metrics in late-myelinating tracts correlated with semantic verbal fluency, a cognitive function known to decline in AD. These findings corroborate the preferential vulnerability of late-myelinating tracts, and illustrate an application of WMTI metrics to characterizing the regional course of WM changes in AD.
尸检和影像学研究观察到，白质（WM）的退化模式与髓鞘发育相反，这表明存在影响阿尔茨海默病（AD）认知衰退的优先区域易损性。本研究应用了从扩散峰度成像（DKI）得出的新型白质纤维束完整性（WMTI）指标，在此框架内检查AD中的白质组织特性。使用遗忘型轻度认知障碍（aMCI，n = 12）、AD（n = 14）和正常对照（NC；n = 15）受试者的数据，混合模型显示出交互作用：晚髓鞘形成纤维束（即上纵束和下纵束）中轴突密度和髓鞘完整性的特定WMTI指标（即轴突水分数、径向轴突外扩散率）在疾病过程中发生变化，但在早髓鞘形成纤维束（即内囊后肢、大脑脚）的初始阶段保持稳定。晚髓鞘形成纤维束中的WMTI指标与语义言语流畅性相关，语义言语流畅性是一种已知在AD中会下降的认知功能。这些发现证实了晚髓鞘形成纤维束的优先易损性，并说明了WMTI指标在表征AD中白质变化区域进程方面的应用。
