Table I.
Topological correction using spherical harmonics reduces the mean distance error and the proportion of the top 5% outliers in comparison with the averaged “gold standard” brain surface
| Correction | Mean distance error (mm) | Hausdorff distance (mm) | Outlier reduction (top 5%) | Total self‐intersections | ||
|---|---|---|---|---|---|---|
| Forward | Reverse | Forward | Reverse | |||
| None | 0.749 (±0.007) | 0.509 (±0.008) | 10.949 (±0.022) | 4.332 (±0.032) | — | 13 |
| FreeSurfer | 0.641 (±0.007) | 0.563 (±0.007) | 7.910 (±0.056) | 5.270 (±0.041) | 65.4% | 21 |
| SPH | 0.537 (±0.007) | 0.539 (±0.008) | 6.855 (±0.044) | 5.922 (±0.034) | 85.1% | 3 |
Generally, the forward Hausdorff distance and mean distance error metrics measure how well the reconstructed surface matches the “gold standard” mesh; the reverse Hausdorff distance and mean distance error indicate how much information in the “gold standard” mesh was retained in the reconstruction.