Hi Steve,
I'm sending you an example of 2 control scans ( in time intervals of 0 and 5
years), 2 patient scans at the same intervals,the results of siena and
sienax and an excel file with the results tabulated.The upload number is :
934032
Thanks
Antonios-Constantine Thanellas
On Thu, 30 Aug 2007 08:21:17 +0100, Steve Smith <[log in to unmask]> wrote:
>Hi - yes you can expect to see significant atrophy in both groups and
>strong correlation between SIENA and SIENAX.
>
>I'm guessing that your data is maybe problematic, particularly as 5
>years is a long time in the life of an MRI machine, and the two
>timepoints may be hard to combine unless your physicists have been
>very careful to keep things stable.
>
>If you'd like to upload an example image pair with SIENA output we
>can take a look.
>Please upload the files in a single compressed tarfile to
>http://www.fmrib.ox.ac.uk/cgi-bin/upload.cgi
>and then email me the upload ID.
>
>Cheers
>
>
>
>On 30 Aug 2007, at 02:58, Antonios - Constantine Thanellas wrote:
>
>> Dear fsl users, I used sienax, siena and voxelwise siena for cross
>> sectional, longitudinal and statistic analysis between two groups
>> Controls
>> and Parkinsonians.
>>
>> From the 8 sets (each set of 2 scans at intervals of 0 and 5 years) of
>> Controls and after the use of sienax 6 of them showed growth in NBV
>> ( the
>> 5th year’s sienax result had bigger NBV than the 0th year's sienax
>> result)
>> and only 2 of them showed atrophy. I was expecting to see atrophy
>> in all of
>> them so I checked if I did a mistake by considering the scans of
>> the 5th
>> year as the scan of the 0 year but everything was correct. Normally
>> the
>> scans of 5th year should show less NBV than the 0st year’s scans, Am I
>> right? What’s your opinion?Why do I have results that shows growth
>> instead
>> of atrophy?
>> At the same time the results of siena in all Controls showed growth
>> rates
>> instead of atrophy!!Why is that? (I used the set up: siena “0 year
>> scan”
>> “5th year scan” . With the set up siena “5th year scan” “0 year
>> scan” I had
>> almost the same PBVC as previously but in this case showing
>> atrophy. Which
>> setup is the right one and why?)
>>
>>
>> According to S.M Smith et al./neuroimage 36 (2007) 1200-1206 siena and
>> sienax -especially in NBV and PBVC- exhibit high correlation but
>> why in my
>> case I have such uncorrelated results ??(in both siena set ups
>> there are
>> cases where PBVC and NBV give totally opposite information. For
>> instance NBV
>> shows growth and PBVC atrophy.. Which results should I “trust”??)
>>
>> As far as it concerns the Patients group from the 13 sets of data
>> 12 of them
>> showed growth of PBV and only 1 showed atrophy while siena ( with
>> the set
>> up: siena “0year scan” “5th year scan”) showed growth is 7 cases
>> and atrophy
>> in 6.
>>
>> Totally unexpected values for both Controls and Patients. Do you
>> have an
>> idea on why this happens?
>>
>> I also run voxelwise siena and found some evidence of atrophy among
>> patients
>> (compared to the healthy subjects) but since the results of siena –
>> sienax
>> are bizarre , I can’t rely on the results of randomise, can i? since
>> randomise uses as input the results of siena then these significant
>> areas of
>> atrophy among patients are wrong…Am I right?
>>
>> Correct me if I’m wrong , normally I should expect NBV in Controls
>> to reveal
>> atrophy between older and new scans , a result that should agree
>> with the
>> siena results and as far as it concerns patients more atrophy (in
>> both siena
>> and sienax) should be expected comparing to controls..
>>
>> I would really appreciate your help
>>
>>
>> Thanks a lot for your time
>> Antonios-Constantine Thanellas
>
>
>------------------------------------------------------------------------
>---
>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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