Hi Alfred,

using FS longitudinal will increase reliability of measurements and is always the right tool for longitudinal studies. However, images will look consistently different across the two scanners. You will never know if the differences that you find are caused by the scanner change or by changing anatomy. It's really worse than 'far less than ideal'.

Best, Martin

On 06/22/2014 02:01 PM, Alfred Ochs wrote:

Colleagues,

We are preparing to perform longitudinal pilot studies a group of subjects and controls under far less than ideal conditions.  The initial MRI scans were done clinically on a 1.5T Siemens scanner using the ADNI Siemens scanning protocol.  The follow-up scans need to be done on a 3.0T Phillips (research, i.e., gratis) scanner using the ADNI Phillips protocol.   Am I correct in assuming that the FreeSurfer longitudinal pipeline will somewhat iron out the inherent segmentation & parcellation differences between MRIs taken on these two machines?

Thank you,  Alfred Ochs




_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer

-- 
Martin Reuter, Ph.D.

Instructor in Neurology
  Harvard Medical School
Assistant in Neuroscience
  Dept. of Radiology, Massachusetts General Hospital
  Dept. of Neurology, Massachusetts General Hospital
Research Affiliate
  Computer Science and Artificial Intelligence Lab,
  Dept. of Electrical Engineering and Computer Science,
  Massachusetts Institute of Technology

A.A.Martinos Center for Biomedical Imaging
149 Thirteenth Street, Suite 2301
Charlestown, MA 02129

Phone: +1-617-724-5652
Email: 
   mreuter@nmr.mgh.harvard.edu
   reuter@mit.edu
Web  : http://reuter.mit.edu