Application of Multimodal MR Imaging on Studying Alzheimer's Disease: A Survey

The aim of this review is to summarize the current magnetic resonance imaging (MRI) variants applied on the studies of Alzheimer's disease (AD). Experimental findings, advantages and disadvantages, and the prospect of every individual technique will be presented. MRI can be used to investigate the change of the brain in terms of volume, function, white matter track orientation and even mechanical properties and metabolic concentration. Results from volumetric and morphological analysis indicated that the hippocampus reduced by approximately 18%-24% or 3%-4% annually. Functional MRI (fMRI) detected the blood oxygen level dependent (BOLD) signaland suggested thatmedial temporal lobe (MTL) such as hippocampus and entorhinal cortex reduced at the early stage of AD, and frontal, temporal, and parietal cortices at the later stage. In diffusion tensor imaging (DTI), the white matter fiber track integrity is measured but the results are inconsistent. Besides, magnetic resonance spectroscopy (MRS), chemical shift imaging (CSI), arterial spin labeling (ASL), magnetic resonance elastography (MRE) and susceptibility weighted imaging (SWI) will also be included in this review.