Hi Peggy - If you upload the tracula output directories for me here, I'll
take a look:
https://gate.nmr.mgh.harvard.edu/filedrop2/
Thanks!
a.y
On Fri, 19 Jun 2015, Peggy Skelly wrote:
It's been a while, but we are still working on computing our tracts in
tracula!
We are still struggling with variability of the output from 'trac-all
-path'. Running with the default number of iterations, there was enough
variability in the output from multiple runs, that I ran longer iterations
to see if the output would converge to more consistent values. Here is the
fa_avg_weight of the rh.cst for a single set of dwi images processed through
tracula, then trac-all -path run several times (with reinit=0 and default
values for nburnin & nkeep):
nsample=7500: 0.516818, 0.529206, 0.495232, 0.514368, 0.492393, 0.51711
nsample=20,000: 0.521082, 0.513492, 0.50974
nsample=50,000: 0.506167, 0.502324, 0.504106
nsample=100,000: 0.530423
Between 7500 and 50k samples, it does seem like the algorithm is converging,
but at 100k samples the output is out of the range of any previous runs. (I
keep looking for errors in how I ran that one, and am running it again.)
In the reference Yendiki, et.al, 2011, you state that the burn-in and
iterations to ensure convergence is for future investigation. Have you had
any more thoughts or progress on this topic?
We are doing a longitudinal analysis, comparing FA_avg_weight over tracts
pre- and post- a 3-month therapeutic intervention. So we anticipate rather
small changes. Do you have any suggestions for how we handle this
variability?
Thanks,
Peggy
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
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.
