DTI Study In Early White Matter Fiber Bundle Injury Of Alzheimer's Disease

ObjectiveIn this study, we used magnetic resonance Diffusion Tensor Imaging (DTI) to contrastively study the Alzheimer's disease (AD), Mild Cognitive Impairment (MCI) patients and normal elderly people, to detect the changes of brain White Matter Tracts Integrity(WMTI),in order to guide the clinical early intervention.Materials and methodsAlzheimer's disease of 29 patients (13 males,16 females), mild cognitive impairment patients of 31 patients (15 males,16 females) and 31 cases of normal healthy controls (NC) patients (16 males,15 females) were selected in this study. To use the German Siemens (Verio) 3. OT nuclear magnetic resonance instrument, with selecting the eight-channel head orthogonal coil.First head MRI examination were carried out, Some diseases were excluded on MRI image, exclude space-occupying lesions, cerebrovascular disease, hydrocephalus, congenital malformations and other obvious abnormalitieson. After DTI scan were carried out with the following parameters:b value:0,1000,2000 s/mm2,30 scanning direction, layers:45 layers, layer spacing:0, layer thickness 2mm, TR= 9500ms, TE= 104ms, scanning range including bilateral Cerebral hemisphere. The DTI studio processing software were selected as post-processing software, and ROIs were placed on the areas of myelination as follows: myelin early formation area is:posterior cingulate cortex and splenium of corpus callosum;late myelin formation area is:superior longitudinal fasciculus and inferior longitudinal fasciculus. To use SPSS19 t-test with ANOVA, P<0.05 was statistically different.ResultsNC group, MCI group, AD group sex (x2= 0.77, P=0.79), and age (x2 =0.16, P=0.86) was not statistically different. ALL groups were right-handed. Compared with the NC group, the FA value of left superior longitudinal fasciculus was decreased and the MD value of left superior longitudinal fasciculus was increased in the MCI group (P<0.05).Compared with the MCI group, the FA values of left superior longitudinal fasciculus, right superior longitudinal fasciculus and left Inferior Longitudinal Fasciculus was decreased and the MD value of left superior longitudinal fasciculus, right Inferior Longitudinal Fasciculus, left Inferior Longitudinal Fasciculus and left posterior cingutate was increased in the AD group (P<0.05). Compared with the MCI group, the FA values of bilateral superior longitudinal fasciculus, bilateral Inferior Longitudinal Fasciculus, splenium of corpus callosum and bilateral posterior cingulate cortex of the AD group was decreased (P<0.05);The MD value of myelin early formation area (bilateral posterior cingulate cortex and splenium of corpus callosum) of AD group was increased (P<0.05), and the MD value of late myelin formation area (bilateral superior longitudinal fasciculus and bilateral inferior longitudinal fasciculus)was Significantly increased (P<0.01).Conclusions1 The study found that late myelin formation fiber bundle (bilateralsuperior longitudinal fasciculus and bilateral inferior longitudinalfasciculus) was damaged more obvious with the progress of Alzheimer's disease,but myelin early formation fiber bundle (posterior cingulate cortex and splenium of corpus callosum) remained basically stable in the early stages of the disease. This finding confirms the priority destroy on late myelin formation fibre bundle; DTI-WMTI index can reflect the progression of Alzheimer's disease that it has become an important indicator Imaging in monitoring Alzheimer's disease.2 superior longitudinal fasciculus and inferior longitudinal fasciculus were the sensitive structures of early DTI examination in AD patients, which should be regarded as the key area for early detection and early intervention of AD. It was presumed that the DTI findings of superior longitudinal fasciculus may reflect the early changes of AD more sensitively than inferior longitudinal fasciculus.3 It Suggest that MD value of AD patients on the white matter region of myelin late formation may be more sensitively reflect the integrity destroy of the fiber bundle than FA values.