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Hi,

My two-penneth is that you might want to consider changing the number
DOF in the registration. Reducing from 12 to 9 misses out the 'skew'
step, which I think is the only thing in an affine that can really
interfere with asymmetry.

Cheers,
Clare

>>> [log in to unmask] 07/22/04 3:40 PM >>>
Joe,

Thanks for the answer, you confirmed my fears.

Because I am mesuring Heschl's and planum temporale/parietal, it would
seem better for me to do these measurements on the raw image data after
correct for pitch, roll, and yaw. Do I have this correct?

If so, then what are rebuttals to claims of lack of generalizability
because of problems with inter-individual comparisons, and a lack of
common stereotaxic space?

Jason

________________________________

From: FSL - FMRIB's Software Library on behalf of Joe Devlin
Sent: Thu 7/22/2004 10:30 AM
To: [log in to unmask]
Subject: Re: [FSL] registration question



Hi Jason,

No, structural asymmetries present in the original images are maintained
in
the transformed brain, assuming that they don't dominate the image.  For
instance, left and right Heschl's gyrus differ on the rostral-caudal
axis
in normal brains and this difference is maintained when transforming the
brain into MNI space because the linear transformation can not alter
relative positions within the image.  If the asymmetry was enormous, on
the
other hand, then it would be reduced by trying to match a normal
template.  For instance, large lateralised strokes and hydrocephalus
typically wreak havoc with registration.

Hope this helps.
Joe