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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 [log in to unmask] http://www.medizin.uni-tuebingen.de/kinder/epn ____________________________________________________