Dear FreeSurfer team,

Repost: Please let me know if the answers are too obvious or the questions are inappropriate for this forum! 

I'm currently doing a structural FS analysis with 50 Multiple Sclerosis (MS) patients and 25 Healthy Controls (HC). FLAIR-lesions were drawn onto the aseg.mgz as White Matter Hypointensities (=77). I've finished the analysis, but have some questions regarding my results.

Results:

	HC (n=25)	MS (n=50)	p-value
Mean TIV (SD) [ml]	1594.9 (154.7)	1559.5 (140.1)	> 0.05
Mean WMV (SD) [ml]	503.6 (57.3)	485.2 (59.5)	> 0.05
Mean GMV (SD) [ml]	657.2 (69.9)	635.1 (47.9)	> 0.05
Mean WMHV (SD) [ml]	1.12 (0.4)	5.97 (5.7)	0.0000677

1) Does these results look trustworthy/reliable? WMV < GMV?

2) What is the difference between WMV+GMV and TIV? CSF? Ventricles?

3) I find no atrophy in the MS patients? Do you have an idea why? If not, don't answer this.

4) What is White Matter Hypointensities comprised of in HC?

5) What is the best estimate of total white matter volume? 

Best, Silas