Hi Hans,
> Is there any way to substract two PET or MRI with ImCalc or Mean
> functions, for example preoperative and
> postoperative MRI or PET to recognize exactly resected hypometabolic
> area or resected cortex ?
You could just hit Imcalc, choose your images, enter a name, and enter
i1-i2 as the expression to evaluate. This of course is very crude and
will likely give you all kinds of differences pertaining to different
positions in the scanner etc.
You could try the same after you normalised the images, which probably
makes more sense, but it might also be worthwhile doing an only affine
normalisation since using a non-linear component might distort your
lesion in the post-op-image because SPM will try to match features that
are not there anymore. A further option might be to coregister image 2
to image 1 and then calculate the difference, but I have noo experience
with this.
Alternatively, get Chris Rorden's amazing MRIcro 1.32, select your
pre-op image and overlay your post-op image over it (again, perhaps only
after accounting for positional differences). You should be able to see
your differences right away.
Good luck!
Marko
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Marko Wilke, MD
Research Fellow, Imaging Research Center
Children's Hospital Research Foundation
3333 Burnet Avenue - ML 5031
Cincinnati, OH 45229
Phone +1 (513) 636-0142 FAX +1 (513) 636-3754
[log in to unmask] http://www.irc.chmcc.org
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