Dear Dr Doug,

I followed wiki to adjust the volumetirc measures to eTIV usign the command 

mri_label_volume -eTIV \
 $sdir/transforms/talairach.xfm 1948 \
 $sdir/aseg.mgz 17 53

Kindly,

1. What is the saling factor stands for and why it is specifically "1948 " is this only relevant to volumetrics? if so what is the scaling factor for surfaces?

2. I am wondering if there is any command to adjust surface area to eTIV similar to the command "mri_label_volume", and how to do this adjustment so I highly appreciate any ideas?

-----Original Message-----

From: freesurfer-bounces@nmr.mgh.harvard.edu [mailto:freesurfer-bounces@nmr.mgh.harvard.edu] On Behalf Of Douglas N Greve

Sent: Monday, May 8, 2017 5:55 PM

To: freesurfer@nmr.mgh.harvard.edu

Subject: Re: [Freesurfer] Surface area

Yes, I would recommend making some kind of adjustment. As with all such adjustments, the adjustment you choose will dictate how you interpret the results (eg, a eTIV adjustment means something different that an adjustment for whole brain volume). For surface area,  I usually adjust the eTIV. It might seem strange to adjust surface area by a volume, but for a highly folded surface, the surface area actually goes up linearly with the volume. But adjusting by total surface area is ok too.

 

 

On 05/08/2017 02:29 PM, John Anderson wrote:

> Dear Freesurfer experts,

> I know that the grey or white matter volume measures for the ROIs

> reported  in "wmparc.mgz" can be adjusted for the total intracranial

> volume.... Is is correct to do the same for surfaces? I mean can the

> surface of an ROI (e.g. precentral) be adjusted to total surface area?

> If yes, this must be done for total white right or total left

> depending  on the ROI if it is left or right, correct?

> 

> Thank you

> John

> 

> 

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--

Douglas N. Greve, Ph.D.

MGH-NMR Center

greve@nmr.mgh.harvard.edu

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