Hi Diederick, In a longitudinal study you need to ensure identical acquisition and processing, else you'll introduce a systematic bias. Some of my recent analyses indicate that even updating the software on the scanner can bias your results. Hardware changes are worse.
Best Martin On Dec 20, 2010, at 6:48 AM, Diederick Stoffers <d.stoff...@gmail.com> wrote: > Hi all, > > I have a dataset with AD patients that were scanned twice, once at 1.5T and > once at 3T at an interval of a few years. The ICV values are lower for almost > all subjects at timepoint two (FS 5.0). Isn't ICV in the later FS versions > supposed to be independent of brain volume as it is based on a scaling factor > derived from the Tailairach transform of the skull? Many thanks! > > Cheers, > > Diederick > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer _______________________________________________ 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.
