dti parameters

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dti parameters

gabriele pasqua
Hi, 
I am gabriel 
I’m using version 4.5.0-1 and I extracted FA values in some specific tracts of spinal cord.
I would like to extract other parameters in order to improve my analysis. 
Can you explain what are Determinant, Mode, LinearMeasure and the other?
How can I compute Longitudinal Diffusivity, Radial and Axial Diffusivity and ADC ( Apparent Diffusion Coefficient) ? 


thank you
bye for now

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Re: dti parameters

inorton
Hi Gabriel,


The articles discussing these measures are:


Please note that we have removed the "Projection X/Y/Z", "RAIMaxEigenvec X/Y/Z", "MaxEigenvec X/Y/Z" and "D11,D22,D33" measures from the nightly version, so they will not be in the next release. We do not recommend that these are used (they are not commonly used in the literature, so we removed to reduce the complexity of the module).

In the current release version we have Trace, which is 3*Mean Diffusivity (sometimes known as ADC). The next release version will also have Mean Diffusivity as a separate measure for convenience.

Best,
Isaiah


On Wed, Sep 7, 2016 at 4:52 AM, gabriele pasqua <[hidden email]> wrote:
Hi, 
I am gabriel 
I’m using version 4.5.0-1 and I extracted FA values in some specific tracts of spinal cord.
I would like to extract other parameters in order to improve my analysis. 
Can you explain what are Determinant, Mode, LinearMeasure and the other?
How can I compute Longitudinal Diffusivity, Radial and Axial Diffusivity and ADC ( Apparent Diffusion Coefficient) ? 


thank you
bye for now

_______________________________________________
slicer-users mailing list
[hidden email]
http://massmail.spl.harvard.edu/mailman/listinfo/slicer-users
To unsubscribe: send email to [hidden email] with unsubscribe as the subject
http://www.slicer.org/slicerWiki/index.php/Documentation/4.3/FAQ


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Re: dti parameters

O'Donnell, Lauren J., Ph.D.
In reply to this post by gabriele pasqua
Hi Gabriele,

The maximum eigenvalue, lambda 1, parallel diffusivity, and also axial diffusivity are all the same thing. The original mathematical terms are the first two, while the second two were introduced to help interpret the measures in terms of a hypothesized single fiber tract being modeled by the tensor.

The perpendicular or radial diffusivity is equal to the average of the smaller two eigenvalues.

I hope this helps.

Lauren

Lauren O’Donnell, Ph.D.
Assistant Professor, Harvard Medical School
http://scholar.harvard.edu/laurenjodonnell
1249 Boylston St., Room #210
Boston, Massachusetts 02215
[hidden email]

On Sep 14, 2016, at 4:57 PM, Isaiah Norton <[hidden email]> wrote:

Hi Gabriele,

They are identical. I'm not sure why we have both, but I assume for some historical reasons. Perhaps my PI Lauren O'Donnell (original author of most of Slicer diffusion) will know more...

Best,
Isaiah

On Wed, Sep 14, 2016 at 7:06 AM, gabriele pasqua <[hidden email]> wrote:
ok I thank you so much.
Can you please explain me the difference between  MaxEigenvalue (the largest of the three eigenvalues of the diffusion tensor (also called lambda 1) and ParallelDiffusivity (this is equal to the first eigenvalue, lambda 1)?
 The first eigenvalue is not by force the maximum one and the MaxEigenValue is not by force what we usually call lambda1. Is it correct?

On Wed, Sep 7, 2016 at 4:04 PM, Isaiah Norton <[hidden email]> wrote:
Hi Gabriel,


The articles discussing these measures are:


Please note that we have removed the "Projection X/Y/Z", "RAIMaxEigenvec X/Y/Z", "MaxEigenvec X/Y/Z" and "D11,D22,D33" measures from the nightly version, so they will not be in the next release. We do not recommend that these are used (they are not commonly used in the literature, so we removed to reduce the complexity of the module).

In the current release version we have Trace, which is 3*Mean Diffusivity (sometimes known as ADC). The next release version will also have Mean Diffusivity as a separate measure for convenience.

Best,
Isaiah


On Wed, Sep 7, 2016 at 4:52 AM, gabriele pasqua <[hidden email]> wrote:
Hi, 
I am gabriel 
I’m using version 4.5.0-1 and I extracted FA values in some specific tracts of spinal cord.
I would like to extract other parameters in order to improve my analysis. 
Can you explain what are Determinant, Mode, LinearMeasure and the other?
How can I compute Longitudinal Diffusivity, Radial and Axial Diffusivity and ADC ( Apparent Diffusion Coefficient) ? 


thank you
bye for now

_______________________________________________
slicer-users mailing list
[hidden email]
http://massmail.spl.harvard.edu/mailman/listinfo/slicer-users
To unsubscribe: send email to [hidden email] with unsubscribe as the subject
http://www.slicer.org/slicerWiki/index.php/Documentation/4.3/FAQ





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[hidden email]
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To unsubscribe: send email to [hidden email] with unsubscribe as the subject
http://www.slicer.org/slicerWiki/index.php/Documentation/4.3/FAQ