Table 2.
Errors in Global Normalized Brain Volumes per Subject due to Segmentation Misclassifications in the MS Group
| Segmentation | % Difference | % Difference |
|---|---|---|
| Outputs Compared | (Mean) | (SD) |
| cGMF-uGMF | 1.04 | .33 |
| cGMF-c1GMF | −.28 | .26 |
| cGMF-c2GMF | 1.31 | .27 |
| uGMF-c1GMF | −1.33 | .27 |
| uGMF-c2GMF | .28 | .26 |
| cWMF-uWMF | −1.67 | .58 |
| cWMF-c1WMF | 0.53 | .52 |
| cWMF-c2WMF | −2.20 | .42 |
| uWMF-c1WMF | 2.16 | .41 |
| uWMF-c2WMF | −0.53 | .52 |
| cBPF-uBPF | .026 | .04 |
| cBPF-c1BPF | .025 | .04 |
| cBPF-c2BPF | .0006 | .002 |
| uBPF-c1BPF | −.0007 | .002 |
| uBPF-c2BPF | −.025 | .04 |
Examples of differences between segmentation output types; uncorrected (u, raw); correction of misclassifications related to either deep gray matter contouring (c1), T1 hypointensities (c2), or both (c, dually corrected).
GMF = gray matter fraction; WMF = white matter fraction; BPF = brain parenchymal fraction.
Percent differences were calculated using the intrasubject differences between the 2 values divided by that subject's first value listed in each row (eg, cGMF - uGMF = [(cGMF - uGMF)/cGMF)]*100%).