The National Centre for Research and Care of Alzheimer's and Mental Diseases, Brescia, Italy.
J Alzheimers Dis. 2010;19(3):963-76. doi: 10.3233/JAD-2010-1295.
Although it is established that Alzheimer's disease (AD) leads to cerebral macrostructural atrophy, microstructural diffusion changes have also been observed, but it is not yet known whether these changes offer unique information about the disease pathology. Thus, a multi-modal imaging study was conducted to determine the independent contribution of each modality in moderate to severe AD. Seventeen patients with moderate-severe AD and 13 healthy volunteers underwent diffusion-weighted and T1-weighted MR scanning. Images were processed to obtain measures of macrostructural atrophy (gray and white matter volumes) and microstructural damage (fractional anisotropy and mean diffusivity). Microstructural diffusion changes independent of macrostructural loss were investigated using an ANCOVA where macrostructural maps were used as voxel-wise covariates. The reverse ANCOVA model was also assessed, where macrostructural loss was the dependent variable and microstructural diffusion tensor imaging maps were the imaging covariates. Diffusion differences between patients and controls were observed after controlling for volumetric differences in medial temporal, retrosplenial regions, anterior commissure, corona radiata, internal capsule, thalamus, corticopontine tracts, cerebral peduncle, striatum, and precentral gyrus. Independent volumetric differences were observed in the entorhinal cortex, inferior temporal lobe, posterior cingulate cortex, splenium and cerebellum. While it is well known that AD is associated with pronounced volumetric change, this study suggests that measures of microstructure provide unique information not obtainable with volumetric mapping in regions known to be pivotal in AD and in those thought to be spared. As such this work provides great understanding of the topography of pathological changes in AD that can be captured with imaging.
虽然已经确定阿尔茨海默病（AD）会导致大脑宏观结构萎缩，但也观察到了微观结构扩散变化，但目前尚不清楚这些变化是否提供了有关疾病病理学的独特信息。因此，进行了一项多模态成像研究，以确定每种模态在中度至重度 AD 中的独立贡献。17 名中度至重度 AD 患者和 13 名健康志愿者接受了弥散加权和 T1 加权磁共振扫描。对图像进行处理以获得宏观结构萎缩（灰质和白质体积）和微观结构损伤（各向异性分数和平均扩散系数）的测量值。使用 ANCOVA 研究了与宏观结构损失无关的微观结构扩散变化，其中使用宏观结构图作为体素协变量。还评估了反向 ANCOVA 模型，其中宏观结构损失是因变量，微观结构弥散张量成像图是成像协变量。在控制了内侧颞叶、后扣带回、前连合、放射冠、内囊、丘脑、皮质桥束、大脑脚、纹状体和中央前回的体积差异后，观察到了患者和对照组之间的扩散差异。在额下回、颞下回、后扣带回、胼胝体和小脑也观察到了独立的体积差异。虽然众所周知 AD 与明显的体积变化有关，但这项研究表明，微观结构的测量值提供了独特的信息，而这些信息是通过对 AD 中关键区域和被认为是未受影响的区域进行体积映射无法获得的。因此，这项工作提供了对 AD 中可以通过成像捕捉到的病理变化的分布的深入了解。
