Hi Zeke,
Thank you for your quick reply.
I am specifically interested in examining the ventricles
and calculated the percent differences for these segmented areas:
Left lateral ventricle = 2.08%
Left inferior lateral ventricle = 6.81%
3rd ventricle= 6.31%
4th ventricle =2.68%
Right lateral ventricle = 0.40%
5th ventricle =200%
I am a bit concerned of the 5th ventricle as it is well greater than the expected 5% difference you suggested. However, I assume the other percent differences are within normal range? This is the first time I am using Freesurfer so I just want to confirm that my results are correct.
Thank you in advance for your help. It is very much appreciated!
Tamara
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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