Hi Roberta,
I assume you want to do voxel-based morphometry, but the general ghist
goes for fMRI studies as well: the problem is not that you cannot
technically compare the images after normalization, but that partial
volume effects will be different between the images if they were
acquired with different spatial resolution. Any systematic difference
between series used to acquire data will be a confound which may make it
impossible to use that data (e.g., if all patients were acquired with
one sequence and all controls with another, that would invalidate all
group comparisons as sequence and group are perfectly correlated).
Depending on how bad this is in your case, it may be possible to combine
the data by modeling your sequence as a confound, similar to approaches
pooling data from different scanners in multi-site studies. Perhaps
papers on this topic give you further clues. However, if you can go
without the subjects acquired with a different sequence, I would suggest
to do so.
Cheers,
Marko
Roberta Biundo wrote:
> Hi everyone
>
> I was wondering if I can use imagines acquired with the same machine
> but with different slides number due to a different period time
> acquisition. I thought that with the pre-processing if I use the
> same normalization model (voxel numbers, mni space etc) for all the
> imagines I can get smwc1 files that can be compared. Is it that
> alright?
>
>
> thank you
>
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
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http://www.medizin.uni-tuebingen.de/kinder/epn
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