and just to chime in, before anyone flames us on this topic (as has happened in the past), we would *love* to have the resources to track down and eliminate this kind of thing, but it is very, very difficult to get NIH funding to do so.

cheers
Bruce


On Thu, 12 May 2016, Z K wrote:

Hello Tamara,

It IS expected to see differences in volumetric data calculated when
using versions if freesurfer compiled for different platforms. That is
why we make the claim of "When processing a group of subjects for your
study, it is essential to process all your subjects with the same
version of freesurfer, on the same OS platform".

You dont specify the % differences in your email below, but we have
found that the differences observed in Mac vs. Linux will typically have
deltas of less than 5%. Sometimes larger percent differences are
observed in smaller structures, only because the delta of a single voxel
can carry a larger percentage weight for smaller structures.

-Zeke


On 05/12/2016 10:20 AM, Tamara Tavares wrote:
Hello All,

I was hoping someone would be able to shed some light on an issue I have
been having concerning the volumetric data calculated by FreeSurfer
(version 5.3) using the asegstats output file. For information purposes,
I am currently using the following command line: recon-all –I [path] –s
–sd [Path] –segmentation –all.


I have noticed some differences in the volumetric outputs from a scan I
ran on a Linux computer (ubuntu kernal version 3.13.0-85) and the same
scan ran on a Mac OS version 10.10.5. These differences in volume range
from 5.2-639.4. I have been having difficulty in finding the source of
this discrepancy. Are discrepancies commonly found? Could the different
computers and operating systems be the reason for these discrepancies?


I really appreciate your time and assistant with this issue.

Thank you in advance for your help!


Tamara



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