Note that a bug in the calculation of the supratentorial volume was recently identified (see archives), so if you want to use that measure you should get the fixed version of mri_segstats and regenerate the aseg.stats files.

cheers, -MH

On Fri, 2012-03-30 at 09:12 -0400, Bruce Fischl wrote:

Hi Gabriela

it's hard to get a stable ICV measure from only a T1-weighted image, since you can't really distinguish bone from air. You can use supra tentorial, but you are testing a slightly different hypothesis (i.e. that hippocampal volume is changing faster than supratentorial volume).

cheers Bruce

On Fri, 30 Mar 2012, HOSSU Gabriela wrote:

...

Dear all,

I am working with FreeSurfer version 5.10 from 2 months. I am interested in hippocampus volume measurements and I want to normalize them with the intracranial volume.

We have scanned about 4 times the same 2 healthy subjects (3T GE HDxt, 8 channel coil). 3D acquisitions were made with the BRAVO GE sequence in coronal and sagittal planes (roughly with the same parameters) .

On the hippocampus we obtained about 5% intra subject variation but for the ICV intra subject variation is around 15%.

With the supra tentorial volume estimations, the variation is around 2%.

Any idea to explain this so important difference for the ICV estimation?

Can we use the supra tentorial volume in order to normalize our hippocampus estimations?

Thanks,

Gabriela HOSSU, Ph.D.

Chef de projet

CIC-IT Nancy (Inserm CIT801)

CHU de Nancy Brabois

4ème étage Tour Drouet

Rue du Morvan

54511 VANDOEUVRE-LES-NANCY

FRANCE

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