FreeSurfers,
I am using the longitudinal processing stream to look at change in the lateral ventricles at several timepoints. As a control measure, we are running two consecutive baseline images in the scanner. These images were done back-to-back, exactly the same, and the subject did not get out of the scanner nor reposition. Motion was not a problem. I have processed this first subject, and the longitudinal stream gives me a 2% change in lateral ventricular volume, comparing the two baseline scans. This is bigger than I'd like to see, as we are interested in changes over time as small as 2%. Is this kind of variability expected, or am I doing something wrong? I just used the first baseline as tp1, processed it cross-sectionally, and then longitudinally, and then I used the second baseline as tp2.
Thanks, Dana
Dana W. Moore, Ph.D. Neuropsychology Fellow Cornell Neuropsychology Service Weill Medical College of Cornell University New York Presbyterian Hospital Department of Neurology & Neuroscience 428 East 72nd Street, Suite 500 New York, NY 10021 Phone: 212-746-2441 Fax: 212-746-5584 Email: dwm2003@med.cornell.edu