[Mristudio-users] transverse diffusion parameters

[susumu mori]

I think it doesn't make too much sense to go below 0.15 for FA threshold.
As FA goes down, the fiber orientation has less meaning; there is no
orientation for a sphere and because of noise, even perfectly sphere media
could be FA = 0.1.

I think Cut is a better approach. Trajectory in between two ROIs has a
strong anatomical constraint and has very small false positive.

If you are interested in transverse diffusivity, you can use
(Evalue1+Evalue2)/2. (assuming 3 Evalues are numbered 0, 1, 2).

2DFA2-3 and FA1-3 are metrics to measure difference between Evalue1 and 2
and Evalue0 and 2. We calculate them, but honestly, I'm not sure if it has
much meaning.



On Wed, Mar 6, 2013 at 12:46 PM, Prachi Dubey <pxd2010 at gmail.com> wrote:

>
> Thank you Hangyi thats very helpful.
>
> Do you propose it is best to stick to 0.2 threshold? or there is another
> lower but reliable threshold. My priorty is to get the most reproducible
> results for mean tract diffusion parameters.
>
> also what do you think will be more reliable for quantitative purposes,
> using cut function to exclude the fiber edge or using the entire tract.
>
> Also would like to hear your comments on eigen value1 and 2 and 2DFA2-3
> and 2DFA1-3. And how these are computed, how specifically they differ from
> FA and Trace.
>
> Prachi
> On Wed, Mar 6, 2013 at 12:36 PM, Hangyi Jiang <hjiang at jhmi.edu> wrote:
>
>>
>> personally,  I think 0.1 is too low to get reliable (or consistent) fiber
>> tracking results.
>>
>> best,
>>
>> hangyi
>>
>>
>>  ------------------------------
>> *From:* mristudio-users-bounces at mristudio.org [
>> mristudio-users-bounces at mristudio.org] on behalf of Prachi Dubey [
>> pxd2010 at gmail.com]
>> *Sent:* Wednesday, March 06, 2013 12:10 PM
>> *To:* DTI Studio, ROI Editor, DiffeoMap Questions/Support
>> *Subject:* [Mristudio-users] transverse diffusion parameters
>>
>>   Hi,
>>
>> Any thoughts on how low one could go on FA threshold for tracking without
>> introducing too much noise. I am using FA=0.2, and a lot of my patients
>> have very severely atropic tracts and it is excluding a lot of the data. I
>> can track more fibers if go as low as 0.1 but that makes me worry if I am
>> introducing tracking error.
>>
>> Also what has your experience been with transverse diffusion values,
>> eigen value1 and 2 and 2DFA2-3 and 2DFA1-3. In my dataset they are more
>> sensitive than FA or Trace.
>>
>> Any thoughts, comments appreciated. Prachi
>>
>> --
>>
>> Prachi Dubey, MD MPH
>> ph:4109614841
>>
>> _______________________________________________
>> mristudio-users mailing list
>> mristudio-users at mristudio.org
>> http://lists.mristudio.org/mailman/listinfo/
>> Unsubscribe, send a blank email to:
>> mristudio-users-unsubscribe at mristudio.org
>>
>>
>
>
> --
>
> Prachi Dubey, MD MPH
> ph:4109614841
>
> _______________________________________________
> mristudio-users mailing list
> mristudio-users at mristudio.org
> http://lists.mristudio.org/mailman/listinfo/
> Unsubscribe, send a blank email to:
> mristudio-users-unsubscribe at mristudio.org
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.mristudio.org/pipermail/mristudio-users/attachments/20130306/b1a1dd2f/attachment.html