[Mristudio-users] Axial / radial

[susumu]

Hi Igor,

 

Axial diffusivity is the same as Eigenvalue0 in DtiStudio.

 

Radial diffusivity is (Eigenvalue1 + Eigenvalue2)/2. DtiStudio doesn't
provide this number. I think we should add this for the next version.

You can create (Eigenvalue1 + Eigenvalue2) image using the calculation
function of RoiEditor, once you saved Eigenvalues.

 

The advantage of using the axial / radial diffusivity is this;

 

When you observe "lower FA", there are two possible mechanisms;

1) It's low because the longest axis (Eigenvalue0 or axial diffusivity)
decreased

2) It's low because the second and third (Eigenvalue1 and Eigenvalue2 or
radial diffusivity) increased.

 

These two possible mechanisms can't be differentiated by FA (information
degeneration), which may carry important biological information. In many
cases, #1 and #2 occur simultaneously, though.

You may want to read the SK (Victor) Song's series of papers on this
subject. I'm not aware of review papers about it.

 

Susumu

 

 

  _____  

From: mristudio-users-bounces at mristudio.org
[mailto:mristudio-users-bounces at mristudio.org] On Behalf Of Igor Korolev
Sent: Sunday, April 27, 2008 10:57 PM
To: mristudio-users at mristudio.org
Cc: Andrea Bozoki
Subject: [Mristudio-users] Axial / radial

 

Dear All,

Is there a way to obtain the radial and axial diffusivity values from a 3D
image in DTIStudio in the same way that FA values can be obtained?

Also, are there any solid review articles you would recommend on the
biological significance of radial and axial diffusivity as measured with
DTI?

Thank you,
Igor

-- 
------------------------------------------------------------------
Igor O. Korolev
Physician-Scientist Training Program (D.O./Ph.D.)
College of Osteopathic Medicine
Neuroscience Program
Michigan State University
Email: Igor.Korolev at radiology.msu.edu 

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