MR diffusion tensor imaging-based white matter studies in mild cognitive impairment and Alzheimer disease / 中华放射学杂志

ABSTRACT

Objective To evaluate the microstructural integrity of white matter (WM) in mild cognitive impairment ( MCI ) and Alzheimer disease (AD) using DTI technique, and to explore the relationship between WM abnormalities and cognitive dysfunction. Methods Nine cases of amnestic MCI, 15 cases of mild probable AD and 11 cases of normal controls (NC) with normal-appearing WM (NAWM) were studied using 3. 0 T MR system. Fractional anisotropy (FA) and mean diffusivity (MD) were measured in different WM areas. One-way analysis of variance was used to test the difference among the three groups for DTI indices. Spearman Correlation analysis was applied to reveal the correlation between the DTI indices and the MMSE and CASI scores. Results The FA value in parietal, centrum semiovale, posterior cingulate gyrus, parahippocampus, temporal and frontal WM in MCI was 0. 31 ± 0.03,0. 39 ± 0. 03,0. 62 ± 0. 05,0. 59 ± 0. 05,0. 47 ± 0. 08,0. 32 ± 0. 04, respectely, and MD value was ( 899 ± 30 ) × 10-6,(782±53) × 10-6, (732±45) × 10-6, (806±38) × 10-6, (772 ± 55) × 10-6, (792 ± 35) × 10-6 mm2/s. The FA value of these regions in AD was 0. 28 ± 0. 04, 0. 37 ± 0. 03,0. 55 ± 0. 06,0. 52 ± 0.05,0.40±0. 05,0. 27 ± 0. 04,and MD value was (912±37) × 10-6,(800 ± 67) × 10-6, (762 ± 46) × 10-6, (874±57)×10-6,(822±55)×10-6, (822±39)×10-6 mm2/s. The FA value in NC was 0.36±0.03,0.43±0.05,0.64±0.05, 0.60±0.05, 0.52±0.05,0.33±0.03, and MD value was (866±37)×10-6,(754±54)×10-6,(718±32)×10-6,(810±39)×10-6,(755±48) × 10-6, (785±23)×10-6 mm2/s. Compared with NC, the FA value in parietal WM was significantly decreased in MCI(P<0. 01 ), The significantly reduced FA values in parietal, centrum semiovale, posterior cingulate gyrus, parahippocampus, temporal and frontal WM , as well as significantly elevated MD values were found in AD(P <0. 05). There was significant correlation between these DTI indices and MMSE and CASI scores (P<0.05). Conclusions MR DTI can detect WM abnormalities in AD and MCI. The parietal WM abnormalities and the disconnection of WM circuitry may play an important role in the development of dementia.