Thanks for the advice. But the abstracts aren't available online. Can you
put them on the email list? Thanks.
-----Original Message-----
From: Stephen Smith [mailto:[log in to unmask]]
Sent: Monday, July 15, 2002 7:51 AM
To: [log in to unmask]
Subject: Re: [FSL] Cortex thickness analysis
Hi.
On Thu, 11 Jul 2002, Andy Goldfine wrote:
> We're interested in using SIENA to compare gray matter thickness between
> groups (like VBM). Has anyone done this before / published on this? Any
> advice for how to do it best? How many subjects would be required?
Thanks.
You can certainly do VBM-like things with the various FSL tools (ie using
BET, FLIRT, FAST, and then doing stats with avwmerge and avwstats) - for
example, see my MTr analysis abstract at ISMRM02 (Smith and De Stefano).
Alternatively, in an approach which is quite different from VBM, an
extension of Siena by Jackie Chen (also ISMRM02) looks at cortical
thickness changes via an explicit (as opposed to via segmentation)
thickness measurement.
> How many subjects would be required?
6. No - seriously, it depends on many factors, the bottom line for example
being the within-group variation compared to the effect size. We have seen
sub-group significant differences when using the SIENA/X packages with
groups of 15ish.
Thanks, Steve.
Stephen M. Smith
Head of Image Analysis, FMRIB
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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