A structural MRI study on semantic dementia

Abstract

Objective To analyze the structural changes of cerebral gray and white matter in patients with semantic dementia (SD), and to promote the knowledge of its pathological changes and mechanisms.  Methods Sixteen SD patients and 17 normal controls were scanned with a 3.0T MR scanner and the whole brain three?dimensional high-resolution structural images and diffusion tensor imaging (DTI) images were acquired. The gray matter density and fractional anisotropy (FA) values of white matter fiber tracts were analyzed by professional statistical softwares or packages respectively. The statistical analysis of gray matter density and FA values between 2 groups were processed by two sample t test, and the statistical threshold were set as P < 0.001, Voxel > 338 and P < 0.001, Voxel > 103 respectively.  Results Compared with the healthy controls, SD patients appeared significantly reduced gray matter density in bilateral temporal lobes, particularly in temporal pole. In addition, SD group showed more areas with grey matter loss in the left cerebral hemisphere, including the left inferior temporal gyrus, left supramarginal gyrus, left inferior parietal gyrus and left middle frontal gyrus. SD group also showed an obviously lower FA value in bilateral white matters of temporal lobe, including bilateral uncinate fasciculus, left cingulum (hippocampus) and bilateral fronto-occipital fasciculus. The abnormal areas of gray matter and white matter showed a high consistency in their anatomical connection.  Conclusions The study helps to reveal the pathological and anatomical basis of semantic dementia, and provides objective evidence for understanding the pathogenesis of semantic dementia.

doi: 10.3969/j.issn.1672-6731.2014.04.007