Hello FSL,
I have run FSL-based tractography on a cohort of 20+ healthy
volunteers. I visually inspected all of them for defects in
registration or FA extraction - all appear good, with no evident
errors. For any given seed ROI, I find that the peak amplitude for
tractography varies tremendously between subjects. My lowest-amplitude
subjects have values in the 100s, while my highest-amplitude subject
have peaks well above 100K. Looking back at the sizes of their seed
ROIs, the quality of their FA, the amount of motion (derived from BET
output), and a dozen other confounds I've imagined, I can't find a good
explanation for why there is such high variability in tractography.
Is this degree of variability among healthy volunteers something that
others find?
A parallel questions: if one uses a higher number of iterations for
probtrackx2 (say, 50,000 instead of the standard 5000), will that
change improve one's signal to noise ratio, or simply elevate all
output (my true tractography plus background, a problem in my
low-amplitude subjects) equally?
Thank you for your insights.
- Jeff
The information in this e-mail is intended only for the person to whom it is
addressed. If you believe this e-mail was sent to you in error and the e-mail
contains patient information, please contact the Partners Compliance HelpLine at
http://www.partners.org/complianceline . If the e-mail was sent to you in error
but does not contain patient information, please contact the sender and properly
dispose of the e-mail.
|