Hi - the tissue type volume calculations are made on the basis of the
partial volume images, not the binary hard classifications - this
gives improved accuracy. Have a look at the sienax script to see
exactly what calculations are made.
Cheers, Steve.
On 21 May 2009, at 01:50, Ranganathan, Sudarshan wrote:
> Hello,
>
> I have a question about the partial volume measurement using (1)
> SIENAX only; and (2) FSLSTATS applied on output binary images
> obtained using SIENAX
>
> Using the following SIENAX command with BET and FAST parameters:
> [sienax MRI_T1_071608_e4_s0.hdr -d -B "-f 0.35" -S "-g -
> p"] I was able to obtain the segmentation result
> report and the binary files for each of white matter, gray matter,
> CSF and all 3 combined as the output, among other files. Firstly,
> using these binary files as input, I used FSLSTATS to calculate the
> partial volumes of white matter, gray matter, CSF as well as total
> brain volume. Secondly, I compared these values with the
> measurements included in the SIENAX report. But however, there is a
> difference in the measurements shown the report versus the output
> obtained from FSLSTATS. For example, the white matter volume differs
> in both by 4 ml, the gray matter volume differs by 18 ml and the
> total brain volume differs by 30 ml. Has anyone faced a similar
> situation or can someone kindly explain the reason for this
> difference?
>
> Kindest regards,
>
> Sudarshan Ranganathan, M.S.
> Doctoral student, Biomedical Engineering, University of Miami
> Graduate Research Assistant, Department of Radiology (R-130)
> University of Miami Miller School of Medicine
> Professional Arts Center (PAC)
> 1150 NW 14 St., Suite 713, Miami, FL 33136
> Work: (305) 243-6559 Fax: (305) 243-3405
> Email: [log in to unmask]
>
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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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