Hi,
We don't have quantitative test-retest comparisons but, all things
being equal, MPRAGE should be fine.
Cheers, Steve.
On 21 Jan 2009, at 12:44, Daniel Reich wrote:
> Steve,
>
> Thanks very much - I appreciate the prompt reply. I'll do what you
> suggest and get back to you.
>
> I believe that the low variability you've reported for both SIENA
> and SIENAX is based on FSE T1-weighted images. Do you have similar
> results with MPRAGE? My impression is that the segmentation might be
> more difficult because the intensities of gray matter and CSF are
> more similar to one another.
>
> -Danny
>
>
>
> On Fri, Jan 16, 2009 at 9:35 AM, Steve Smith <[log in to unmask]>
> wrote:
> I would start by concentrating on a single pair of images that are
> giving a surprisingly large SIENA result; run with the -d debug
> option and look carefully at each stage of the outputs to see if you
> can track down where things are going awry.
>
> Cheers, Steve.
>
>
>
> On 11 Jan 2009, at 16:52, Daniel Reich wrote:
>
> I'm looking for tips on using SIENA and SIENAX with MPRAGE data.
>
> Our data are 1.1 mm isotropic MPRAGE, collected on a 3T scanner. You
> can see
> results for a 31-year-old healthy woman at:
>
> ftp://ms-mri.marburg1.jhmi.edu/pub/10005_sienax.pdf
>
> Scans 1 and 2 are separated by about 6 months; scans 1 and 3 by
> about 2
> years. My impression is that the program is having problems finding
> the
> brain/CSF distinction accurately and reliably. Certainly, a 24%
> change in
> brain volume over 6 months in a healthy person is not desirable, but
> I get
> results like this frequently. Perhaps I'm doing something wrong.
>
> Thanks in advance for the help.
>
>
>
> ---------------------------------------------------------------------------
> Stephen M. Smith, Professor of Biomedical Engineering
> Associate Director, Oxford University FMRIB Centre
>
> FMRIB, JR 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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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR 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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