Hi Freesurfer gurus,
I have been using Tracula to investigate white matter abnormalities in a patient cohort (n=20) compared to matched controls (n=40). In line with the literature, we expected to see reductions in FA in the patients' tracts but instead they have significantly higher FA means. To double-check, we ran TBSS over the same cohorts and got the results as per the literature (I.e. reduced FA in the patient group). The FA, RD, AD, MD and volume outputs are normally distributed and there are no extreme outliners. So wondering:
1. The patient group had significantly reduced tract volumes. If this volume calculation is incorrect I expect it could influence the calculation of the mean FA, RD, AD etc. Is there a way of checking the volume and subsequent calculations? 2. Yendiki et al 2011 had no corrections – do I need corrections? 3. Should I be thresholding tract stats?
Thank you in advance,
Sean Hatton Brain and Mind Research Institute University of Sydney