To evaluate the changes of white matter in Alzheimer's disease(AD) patients by Magnetic resonance diffusion tensor imaging (DTI) and to analyze the diagnostic value of Fractional anisotropy (FA) and Geodesic anisotropy (GA) in detecting white matter abnormalities in AD patients.

MRI routine scan and DTI were performed in 12 AD patients who were diagnosed from August 2014 to August 2015. 16 cognitively normal (NC) healthy elderly volunteers were enrolled, as control group, to this study. The FA and GA of superior longitudinal fasciculus, Cingulate, corpus callosum, internal capsule, frontal lobe, parietal lobe, temporal lobe and occipital lobe white matter were measured. The ROC curve was applied to analyze Fractional anisotropy (FA) and Geodesic anisotropy (GA) parameters to determine the diagnostic value in detecting white matter abnormalities in patients with AD.

Compared to the control group, the FA and GA values in the posterior cingulate were decreased, the FA and GA values of the superior longitudinal fasciculus were decreased, the FA and GA of the white matter in the parietal lobe were decreased, the GA value of the white matter in the frontal lobe was decreased, the GA value of the white matter in temporal lobe was decreased and the GA value of the splenium of corpus callosum was decreased. The differences were statistically significant. The area under the ROC curve was more than 0.700, which was larger than that of FA.

AD patients usuaug show selective and regional damage in the posterior cingulated and the damage in superior longitudinal fasciculus, splenium of corpus callosum, frontal lobe, temporal lobe, parietal cortex and subcortical white matter lesions. The diagnostic value of GA in detection of white matter abnormalities in patients with AD was superior to FA.