Hi Gergely, Was this collected on a Siemens scanner? If so, the Siemen's MPRAGE sequence is such that the "slices" form the "inner loop" of the acquisition -- that is "Number of slices" lines in k-space are acquired for each TR period. So, having a differing number of slices theoretically has an impact on the spatial filtering properties of the acquisition. My intuition suggests to me that this would be a minor effect that would be washed out by other noise and inter-subject differences. But perhaps others have quantitative results in this regard...? (e.g., collecting both sequences on a set of subjects and then looking for differences using an intra-subject design).
cheers, -MH > Hi Freesurfers, > > I have a quick question: > > I have two groups, both measured on the same scanner, with the same > sequence > (3D MPRAGE), and with almost > the same parameters. > > TR/TE/TI/BW/MATRIX/FOV/FOV-phase/Flip angle/Slice thickness/in-plane > resolution... everything is the same, but the number of slices. > Total measurement time was also the same. > > One group was measured with 160 slices, the other with 176. > > Can I compare the two groups in freesurfer? > > Thanx, > > -- > Gergely Orsi > biologist - research associate > Diagnostic Center of Pécs > H-7623 Pécs, Rét str. 2. > Tel.: 0036-70-3174676 > E-mail: gergo.o...@gmail.com > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > The information in this e-mail is intended only for the person to whom it > is > addressed. If you believe this e-mail was sent to you in error and the > e-mail > contains patient information, please contact the Partners Compliance > HelpLine at > http://www.partners.org/complianceline . If the e-mail was sent to you in > error > but does not contain patient information, please contact the sender and > properly > dispose of the e-mail. > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
