Table 1.
Voxel-based pathway metrics and DTT statistical counts.*
| left pathway system | right pathway system | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| upper(AF) | lower (HF) | combined (AF-HF) | upper (AF) | lower (HF) | combined (AF-HF) | |||||||
| pathway metrics* | mean | (SEM) | mean | (SEM) | mean | (SEM) | mean | (SEM) | mean | (SEM) | mean | (SEM) |
| macrostructural metrics | ||||||||||||
| pathway volume | 1.550 | (0.101) | 0.994 | (0.124) | 2.411 | (0.188) | 0.879 | (0.085) | 0.539 | (0.083) | 1.252 | (0.135) |
| pathway mean length | 5.453 | (0.146) | 4.896 | (0.104) | 5.248 | (0.137) | 5.353 | (0.174) | 4.617 | (0.135) | 5.111 | (0.160) |
| cross-sectional area | 28.40 | (1.67) | 20.32 | (2.47) | 46.03 | (3.50) | 16.28 | (1.44) | 11.70 | (1.76) | 24.47 | (2.49) |
| microstructural metrics | ||||||||||||
| anisotropy (A-sigma)** | 0.3175 | (0.0073) | 0.3222 | (0.0077) | 0.3249 | (0.0059) | 0.2974 | (0.0071) | 0.2917 | (0.0059) | 0.3003 | (0.0068) |
| mean diffusivity (D-bar) | 0.7971 | (0.0065) | 0.8208 | (0.0092) | 0.8078 | (0.0068) | 0.8111 | (0.0075) | 0.8338 | (0.0152) | 0.8174 | (0.0084) |
| lambda-min (D-min) | 0.4466 | (0.0099) | 0.4383 | (0.0118) | 0.4405 | (0.0092) | 0.4827 | (0.0079) | 0.4929 | (0.0154) | 0.4810 | (0.0098) |
| lambda-mid (D-mid) | 0.6722 | (0.0074) | 0.6976 | (0.0279) | 0.6863 | (0.0086) | 0.6858 | (0.0104) | 0.7299 | (0.0193) | 0.6966 | (0.0130) |
| lambda-max (D-max) | 1.2731 | (0.0146) | 1.3043 | (0.0099) | 1.2965 | (0.0104) | 1.2646 | (0.0160) | 1.2786 | (0.0160) | 1.2744 | (0.0120) |
| radial diffusivity (D-radial) | 0.5594 | (0.0078) | 0.5680 | (0.0183) | 0.5634 | (0.0081) | 0.5843 | (0.0080) | 0.6114 | (0.0163) | 0.5888 | (0.0105) |
| DTT statistical counts*** | mean | (SEM) | mean | (SEM) | mean | (SEM) | mean | (SEM) | mean | (SEM) | mean | (SEM) |
| number of track beads | 24213 | (3326) | 14659 | (3118) | 38872 | (4236) | 9880 | (1564) | 4964 | (1263) | 14845 | (2648) |
| number of traversed voxels | 793.6 | (51.9) | 508.8 | (63.6) | 1234.5 | (96.4) | 450.2 | (43.6) | 275.9 | (42.7) | 640.9 | (69.0) |
Pathway metrics for amygdalo-fusiform (AF) and hippocampo-fusiform (HF) pathways are reported as the group mean and standard error of the mean (SEM) for the 15 subjects in the study. Pathway volume is given in cm3, mean length is in cm, and mean cross-sectional area is in mm2. The parameters of mean diffusivity (D-bar), tensor eigenvalues (D-min, D-mid, D-max), and radial diffusivity (D-radial) are in units of µm2/ms.
The anisotropy values expressed as FA are (upper, lower, combined): Left -- 0.5017, 0.5078, 0.5113; right -- 0.4748, 0.4671, 0.4787.
The statistical counts (number of track beads and number of traversed voxels) are only presented to indicate the sampling statistics of the data underlying the measurement of bead-based and voxel-based pathway metrics. The number of traversed voxels is the number of 1.25×1.25×1.25-mm voxels that contain at least one bead of one track, where the 1.25×1.25×2.5-mm diffusion-weighted images were interpolated in-plane to 1.25-mm isotropic voxels prior to track computation (4,9). The pathway volume is calculated as number of traversed voxels times [(1.25)3 / 1000] cm3 The number of tracks (track count) was typically 70–220 for the four individual pathways. Track counts are due to many technical factors, and should not be interpreted in biological terms (see text).