Dear Petr, the volumes from the subfields are in voxels. Since the voxels are 0.5mm isotropic, their volumes is (1/8) cubic millimeters. Therefore, you need to divide the volumes by 8 to convert to mm3. Kind regards, /Eugenio
Juan Eugenio Iglesias Postdoctoral researcher BCBL www.jeiglesias.com www.bcbl.eu
Legal disclaimer/Aviso legal/Lege-oharra: www.bcbl.eu/legal-disclaimer
----- Original Message ----- From: "zach petr" zach.petr@post.cz To: "Freesurfer support list" freesurfer@nmr.mgh.harvard.edu Sent: Tuesday, April 15, 2014 4:05:43 PM Subject: Re: [Freesurfer] FS volume discrepancies
Thanks for reply. But adding subfield volumes together leads to too high number compared to overall hippocampus volume. Like 9500 mm3 compared to 2.1 mm3.
Petr
---------- Původní zpráva ---------- Od: Bruce Fischl fischl@nmr.mgh.harvard.edu Komu: Freesurfer support list freesurfer@nmr.mgh.harvard.edu Datum: 15. 4. 2014 14:35:13 Předmět: Re: [Freesurfer] FS volume discrepancies
From Eugenio:
------------------------ Dear Petr, at this point, the hippocampal subfield module is - to some extent - independent from the whole hippocampal segmentation. The values you will obtain from adding the subfield volumes together will be around 15% lower than the volumes from aseg.stat, but they will still be very highly correlated. Kind regards, ------------------------
On Tue, 15 Apr 2014, zach.petr@post.cz wrote:
I have several issues concerning automated volumes calculation. When you look at the aseg.stat for hippocampal volume (in mm3) it gives different value compared to hippocampal subfields volume calculation (which comes in voxels but there is stated that 1 voxel is 0.5mm3). How is it possible? I presume that anatomical definition and subfield incorporation is the same.
Next - if you look at the whole hippocampal formation volume in hippocampal subfield calculations it is way lower compared to the summation of the CA1-CA4 + dentate gyrus = hippocampal formation. What could be explanation of this?
Petr
_______________________________________________ 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. _______________________________________________ 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.