Hi Jesper,
Did you get an opportunity to look at my GM_mod_merg file?
Any thoughts on why my subjects look so different from each other in this
file, or if this is to be expected?
Thx
J
----- Original Message -----
From: "Jesper Andersson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 17, 2010 3:08 PM
Subject: Re: [FSL] FSL-VBM vs Freesurfer
> Dear Jay,
>
>> I've discovered something of interest...
>>
>> I mentioned that I used fslroi to crop the images prior to bias
>> correcting
>> and bet-ing. I had asked if the differing image sizes would be an
>> issue for
>> fslvbm, and Gwenaelle replied that it would not.
>>
>> Since you seemed surprised that my subject volumes looked quite
>> different
>> from each other in the GM_mod_merg file, I have run an experiment
>> using one
>> subject only, a copy of that subject, and a version of that subject
>> cropped differently.
>> The original and copy look identical after processing through the
>> fslvbm
>> scripts, however the newly cropped volume is visibly different from
>> the other 2!
>>
>> Clearly the cropping introduces some alteration, and the widely
>> different cropping
>> parameters for my subjects my seems have contributed to the visible
>> differences. I
>> used the non-linear version of registration btw...would affine been
>> a better choice?
>
> I am not surprised you find a difference, but I would have thought
> that the results you get with cropping would be the better ones. The
> main way in which cropping will affect your results (apart from
> reducing processing time and disk space) is by allowing BET to do a
> better job.
>
> Maybe by now it is better if you uploaded the mod_merge file so we can
> have a look at it.
>
> Jesper
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