[Mristudio-users] question about eigenvalues/vectors

[Katherine L. Ragland]

Thank you.  I will look at those resources.

Katie
________________________________________
From: mristudio-users-bounces at mristudio.org [mristudio-users-bounces at mristudio.org] On Behalf Of susumu mori [susumu at mri.jhu.edu]
Sent: Thursday, December 16, 2010 7:22 AM
To: DTI Studio, ROI Editor, DiffeoMap Questions/Support
Subject: Re: [Mristudio-users] question about eigenvalues/vectors

On Fri, Dec 3, 2010 at 11:02 AM, Katherine L. Ragland <klragland at umc.edu<mailto:klragland at umc.edu>> wrote:
Hello-

I am a fourth year medical student at the University of Mississippi Medical Center working with Dr. Judy James.  We have been using your DTIStudio software for fiber tracking in the fetal brain.  I would like to preface my questions by saying my current knowledge of DTI, eigenvalues, eigenvectors, etc. is quite limited.  If I say something incorrectly, please let me know!

My questions for you deal with eigenvalues and eigenvectors.

1)  What is the clinical applicability of these measurements?  For example, does a shorter primary eigenvector signify a loss of anisotropy and possibly decreased myelination?  What can one infer from increasing or decreasing trends in eigenvalues?

 I have some description about it in our Neuron paper (Mori and Zhang, 51, 527, 2006, Descriptions related to Fig. 10) and entire chapter 7 of my book "Introduction to Diffusion Tensor Imaging" is dedicated to this topic.

2)  Do the eigenvalue 0 and eigenvector 0 correspond to the primary value/vector parallel to axon fibers?

Correct.


2)  How do you calculate the primary eigenvector from the statistics derived from DTIstudio?  (the 3 eigenvectors are given as x, y, and z coordinates)

Not sure about your question. DtiStudio provides Eigenvector0, 1, 2, right? Are you asking how they are calculated internally? In DTI, the first thing we calculate is a 3x3 tensor, from which we can obtain 3 eigenvectors and 3 eigenvalues.


I appreciate any insight you can give.

Thank you very much for this software and your time in reading this.

Sincerely,

Katie Ragland

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