Hi Zoe,

there are basically two approaches if the assumption of fixed head size is violated:
- use the longitudinal stream and see how far it get's you. Especially if the time delta is relatively small, this has good chances to work. It may require edits, so definitely check the results carefully.
- if surface initialization in the long is too far (that is, if the surfaces created in the base are too far away from their final position), there may not be much you can do with editing. If that happens, you may need to drop longitudinal processing and simply use the cross sectionally (independently) processed data. Since that data is the first step in the longitudinal pipeline, it is already there.

Best, Martin

On 05/09/2016 02:57 PM, Hawks, Zoe wrote:

I'm looking to use FS for longitudinal processing in a pediatric population ranging from 6-18 years. From what I've read, the longitudinal stream isn't appropriate because our data violate the assumption of fixed head size. Any advice on how to account for increases in head size would be appreciated. Thank you!
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-- 
Martin Reuter, PhD
Assistant Professor of Radiology, Harvard Medical School
Assistant Professor of Neurology, Harvard Medical School
A.A.Martinos Center for Biomedical Imaging
Massachusetts General Hospital
Research Affiliate, CSAIL, MIT
Phone: +1-617-724-5652
Web  : http://reuter.mit.edu