Su Li, Blamire Andrew M, Watson Rosie, He Jiabao, Aribisala Benjamin, O'Brien John T
Department of Psychiatry, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.
Curr Alzheimer Res. 2016;13(5):534-44. doi: 10.2174/1567205013666151116141416.
Quantitative MRI provides important information about tissue properties in brain both in normal ageing and in degenerative disorders. Although it is well known that those with Alzheimer's disease (AD) show a specific pattern and faster rate of atrophy than controls, the precise spatial and temporal patterns of quantitative MRI in AD are unknown. We aimed to investigate neuroimaging correlates of AD using serial quantitative MRI. In our study, twenty-one subjects with AD and thirty-two similar-aged healthy controls underwent two serial MRI scans at baseline and 12 months. Tissue characteristics were captured using two quantitative MRI parameters: longitudinal relaxation time (qT1) and transverse relaxation time (qT2). The two groups (AD and controls) were statistically compared using a voxel based quantification (VBQ) method based on Matlab and SPM8. At baseline, subjects with AD showed a significant reduction of qT1 and qT2 compared to controls in bilateral temporal and parietal lobes, hippocampus, and basal ganglia. This pattern was also observed at follow-up. Longitudinally, in AD we found a significant increase rather than further reduction of qT1 and qT2 from the baseline in bilateral hippocampus, thalamus and right caudate nucleus. In addition, the longitudinal change of qT1 in left hippocampus was negatively correlated with cognitive decline in AD over the 1-year period, and the general disease severity significantly predicted the amount of increase of qT1 in bilateral hippocampus over 12 months. The longitudinal change of qT2 in left parahippocampus correlated with change in neuropsychiatric features over time. In summary, quantitative MRI parameters were reduced in AD cross-sectionally, but increased over time, showing distinct spatiotemporal patterns from the atrophy in AD. We also showed the clinical relevance of quantitative MRI parameters, indicating their potential promise as new imaging markers in AD.
定量磁共振成像（MRI）为正常衰老和退行性疾病状态下的脑组织特性提供了重要信息。虽然众所周知，阿尔茨海默病（AD）患者相较于对照组呈现出特定的萎缩模式且萎缩速度更快，但AD患者定量MRI的确切空间和时间模式尚不清楚。我们旨在通过系列定量MRI研究AD的神经影像学相关因素。在我们的研究中，21名AD患者和32名年龄相仿的健康对照者在基线期和12个月时接受了两次系列MRI扫描。使用两个定量MRI参数来获取组织特征：纵向弛豫时间（qT1）和横向弛豫时间（qT2）。基于Matlab和SPM8，采用基于体素的量化（VBQ）方法对两组（AD组和对照组）进行统计学比较。在基线期，与对照组相比，AD患者在双侧颞叶、顶叶、海马体和基底神经节的qT1和qT2显著降低。随访时也观察到了这种模式。纵向来看，在AD患者中，我们发现双侧海马体、丘脑和右侧尾状核的qT1和qT2相较于基线期显著增加而非进一步降低。此外，左海马体中qT1的纵向变化与AD患者1年内的认知衰退呈负相关，疾病总体严重程度显著预测了双侧海马体12个月内qT1的增加量。左海马旁回中qT2的纵向变化与神经精神特征随时间的变化相关。总之，AD患者的定量MRI参数在横断面检查时降低，但随时间增加，呈现出与AD萎缩不同的时空模式。我们还展示了定量MRI参数的临床相关性，表明它们作为AD新的成像标志物具有潜在前景。
