Hi - you won't expect to see exact correlation between all subjects as
SIENA has an error of about 0.2-0.3% and SIENAX has an error about 3-4
times this - but as this data is reasonable quality you should expect
to see an _average_ correlation/error between the two measures that
matches the NeuroImage paper.
Your reports that you sent all look reasonable - so hopefully you are
indeed getting average results that are ok. I note though that for one
of the subjects that you sent, the two images into SIENAX are not
exactly the same as the two images you input into SIENA.
Cheers.
On 13 Nov 2007, at 18:22, Antonios - Constantine Thanellas wrote:
> Dear fsl users,
>
> I used siena and sienax to analyze Alzheimer data scans (T1).
> My data were carefully chosen in order to be from the same scanner
> and with
> exactly the same characteristics.
>
> The point is that in more than 30% of the results siena and sienax
> were
> showing totally uncorrelated results (siena showed atrophy and sienax
> showed growth) and in most of the cases not strong correlation (siena
> showing big atrophy ans sienax showing small atrophy). I checked all
> the
> stages of the siena and sienax analysis and there weren't any
> evidence of
> problems during it.
>
> According to Smith et al. Neuroimage 36 (2007) there is a strong
> correlation
> between PBVC and NBV so I'm not sure if i can trust my results.Any
> ideas why
> this happens?
>
> I'm sending you the analysis results of some of my scans to have a
> better
> view of what am i talking about. (ID : 575483)
>
> Thank you
> Antonios Constantine Thanellas
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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)
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