Study of diffusion tensor imaging in subcortical ischemic vascular cognitive impairment

Abstract

Objective Using diffusion tensor imaging (DTI) to explore the microstructure changes of white matter in subcortical ischemic vascular cognitive impairment (SIVCI) and its correlation with cognitive function.  Methods Forty-nine patients with subcortical ischemic cerebrovascular diseases were collected. By using Clinical Dementia Rating Scale (CDR), they were classified into 10 cases of vascular dementia (VaD group), 20 cases of vascular cognitive impairment-no dementia (VCIND group) and 19 cases of normal cognitive function (control group). Conventional MRI and DTI were performed in all cases. Based on the DTI data, voxel-based analysis was used to assess the whole brain region. Correlation analysis was applied to illustrate the relationship between DTI parameters and cognitive scale in VaD patients.  Results Compared with the control group, fractional anisotropy (FA) values of patients in VaD group decreased in medial prefrontal cortex, anterior cingulate cortex, corpus callosum stem, bilateral parietal lobes, right temporal lobe and bilateral orbitofrontal lobes (P = 0.000, for all), and FA values of patients in VCIND group decreased in right inferior frontal gyrus, right hippocampus and bilateral precuneus (P = 0.000, for all). Compared with VCIND group, FA values of patients in VaD group decreased in medial prefrontal cortex, anterior cingulate, corpus callosum, bilateral parietal lobes and right temporal lobe (P = 0.000, for all). Compared with the control group, mean diffusivity (MD) values in VaD group increased in medial prefrontal cortex, corpus callosum, bilateral parietal lobes, bilateral temporal lobes and anterior cingulate (P = 0.000, for all), while in VCIND group increased in bilateral precuneus and right hippocampus (P = 0.000, for all). Compared with VCIND group, MD values in VaD group increased in right medial prefrontal cortex, anterior cingulate cortex, corpus callosum stem, bilateral parietal lobes and bilateral temporal lobes (P = 0.000, for all). The correlation analysis showed that the FA value of medial prefrontal lobe in VaD group was negatively correlated with the time to finish Trail Making Test A (TMT-A; r = - 0.782, P = 0.007), and MD value of bilateral inferior frontal gyrus was positively correlated with the time to complete TMT-A (r = 0.877, P = 0.001).  Conclusions DTI was more sensitive on the white matter microstructure change of SIVCI patients than conventional MRI. It can reflect patient's early cognitive functional changes. Microstructrual change in medial prefrontal white matter is an important factor which may influence the executive functions of patients with SIVCI.

doi: 10.3969/j.issn.1672-6731.2014.04.009