Table 2. Differences in DTI metrics between PD-aMCI and PD-CN and between PD-CN and normal controls.
| Comparison | Metrics | Cluster | Peak voxels | ||||
|---|---|---|---|---|---|---|---|
| Size | MNI coordinates | 1-p value | Anatomical location | ||||
| X | Y | Z | |||||
| PD-CN | Voxel/AD | 317 | 12 | 4 | 16 | 0.98 | R caudate |
| > NC | Voxel/RD | 83 | 12 | 4 | 16 | 0.96 | R caudate |
| PD-aMCI | Voxel/FA | 810 | 10 | -39 | 20 | 0.96 | R corpus callosum splenium |
| < PD-CN | -3 | -17 | 24 | 0.96 | R corpus callosum body | ||
| -8 | -51 | 16 | 0.96 | L cingulum (cingulate gyrus) | |||
| -28 | -56 | 17 | 0.97 | L posterior thalamic radiation | |||
| -19 | -50 | 33 | 0.96 | L posterior corona radiata | |||
| -29 | -54 | 13 | 0.97 | L tapetum | |||
| 10 | -45 | 23 | 0.95 | R cingulum (cingulate gyrus) | |||
| 744 | 33 | -52 | 18 | 0.97 | R posterior thalamic radiation | ||
| 32 | -49 | 8 | 0.95 | R tapetum | |||
| 32 | -53 | 21 | 0.97 | R posterior corona radiata | |||
| 36 | -53 | 18 | 0.96 | R superior longitudinal fasciculus | |||
| 318 | -18 | -1 | 38 | 0.96 | L superior corona radiata | ||
| 313 | -25 | -25 | -10 | 0.95 | L fornix | ||
| TBSS/FA | 9124 | -12 | -9 | 30 | 0.97 | L cingulum body | |
| 11 | -25 | 28 | 0.98 | R cingulum body | |||
| -37 | -54 | 15 | 0.97 | L superior longitudinal fasciculus | |||
| 35 | -12 | 34 | 0.96 | R superior longitudinal fasciculus | |||
| -9 | -29 | 35 | 0.97 | L cingulum (cingulate gyrus) | |||
| 9 | -6 | 33 | 0.97 | R cingulum (cingulate gyrus) | |||
| -27 | -58 | 19 | 0.97 | L inferior longitudinal fasciculus | |||
| 28 | -50 | 19 | 0.97 | R inferior longitudinal fasciculus | |||
| 32 | -62 | 1 | 0.96 | R inferior fronto-occipital fasciculus | |||
| 41 | -28 | -74 | 3 | 0.95 | L inferior fronto-occipital fasciculus | ||
PD = Parkinson’s disease; PD-aMCI = amnestic mild cognitive impairment in PD; PD-CN = cognitively normal PD patient; AD = axial diffusivity; RD = radial diffusivity; FA = fractional anisotropy. TBSS = Tract-based spatial statistics.
Voxel-based DTI metrics (FA, AD, and RD) were compared between PD-CN and normal controls, as well as between PD-aMCI and PD-CN. TBSS-based FA values were also compared between PD-aMCI and PD-CN. The significance level was set at p<0.05 (FWE-corrected). The controlled covariates included age, gender, and disease duration (only for the comparison between PD-aMCI and PD-CN).