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That's correct. The "imported" images are rigidly transformed to be as close to the MNI space as a rigid transform will allow. This is determined by a Procrustes analysis ( https://en.wikipedia.org/wiki/Procrustes_analysis ) of the nonlinear deformations, weighted by the grey matter. Brains in MNI space are a bigger than any typical brain, so the imported images will all appear smaller by comparison. Best regards, -John On 22 March 2017 at 14:18, michel grothe <[log in to unmask]> wrote: > Hi Luca, > > > to my understanding the imported images are only rigidly transformed, so > the size of the brain should not change compared to the original native > space scan (and would be expected to be smaller compared to the MNI space > TPMs). > > > Best, > > Michel > > > ------------------------------ > *Von:* SPM (Statistical Parametric Mapping) <[log in to unmask]> im > Auftrag von PRESOTTO LUCA <[log in to unmask]> > *Gesendet:* Mittwoch, 22. März 2017 14:51 > *An:* [log in to unmask] > *Betreff:* [SPM] R: [SPM] How should rc* images look like? > > > Thank you for your answer! > > I was referring to the x,y,z dimension. I mean that the brain is smaller. > I attach a picture of 5 rc images compared with a contour drawn on the gray > matter TPM. The segmentation for each subject looks perfectly fine. The > starting MRI scans are all 3D T1 volumetric scans (1 mm isotropic voxel) > acquired on different scanners with different field strengths (these are > scans downloaded from the ADNI database). > > > > Best Regards, > > Luca > > > > *Da:* John Ashburner [mailto:[log in to unmask]] > *Inviato:* mercoledì 22 marzo 2017 14:26 > *A:* PRESOTTO LUCA <[log in to unmask]> > *Cc:* [log in to unmask] > *Oggetto:* Re: [SPM] How should rc* images look like? > > > > When you say "all my images are significantly smaller than the TPM", are > you referring to the size of the files or the actual dimensions of the > images? The "imported" rc files should be smaller in size, but their x, y > and z dimensions should be the same as those of the TPM.nii. The reason > for this is that the TPM encodes more than just a single tissue class. > > Best regards, > > -John > > > > On 22 March 2017 at 12:42, PRESOTTO LUCA <[log in to unmask]> wrote: > > Dear experts, > > I'm trying to use dartel for my first time. After reading the manual and > a number of tutorials from google I've used segment on a bunch of t1 images > and I've set the algorithm to save also "dartel imported" images. It is my > understanding from what I've read that rc images are the same maps from the > segmentation, with only the affine transformation, as determined before the > beginning of the segmentation, applied. Is my understanding correct? If so > I'd expect them all to be around the same size of the tpm, just not of the > correct shape. Instead, all my images are significantly smaller than the > TPM. Am I missing something? > > Thank you! > > Luca > > > > > *Rispetta l’ambiente: non stampare questa mail se non è necessario. > Respect the environment: if it's not necessary, don't print this mail.* > > >