[Mristudio-users] ADC-Map Calculation in DTIStudio

Mon Aug 15 18:51:28 EDT 2011

Dear Judy/ Rachael,

ADC is 'apparent diffusion coefficient'. It is defined for the three
coordinate directions, x,y,z (the space in which the subject was in the
scanner).

Note that mean ADC and mean diffusivity is not the same (at least if you
look at the definition). For mean diffusivity, the eigenvalues have to be
estimated from the tensors. In DTI Studio, you can get the 'trace
diffusivity' which equals 3 times the mean diffusivity.

Best

Andreas

  _____  

From: mristudio-users-bounces at mristudio.org
[mailto:mristudio-users-bounces at mristudio.org] On Behalf Of Rachael Gonzales
Sent: Montag, 15. August 2011 16:32
To: DTI Studio, ROI Editor, DiffeoMap Questions/Support
Subject: [Mristudio-users] ADC-Map Calculation in DTIStudio

Hi DTI experts,

In DTIStudio, under the DTI map tab there is an ADC Map calculation
available.  After the calculation, an ADC map - mean image is generated, is
this the apparent or average diffusion coefficient?  

Thanks,

Rachael

****************************************************************************
*************************************************

Judy, in DtiStudio, ADC (or also called MD) should be obtained from "Trace".

Trace is defined as Dxx+Dyy+Dzz. If you divide it by 3, it becomes
"Average diffusion constant (ADC)" or "Mean diffusivity (MD)". We like
to use the term "trace" because it has clear mathematical definition
while ADC is also used for "Apparent diffusion constant", which has a
different meaning from "average diffusion constant".

On Mon, Apr 11, 2011 at 11:58 AM, Judy James <jjames2 at umc.edu> wrote:

Is any one in this group aware of how to calculate ADC maps from the

original DWI images in DTI studio - not DTI images, like how to set the

gradient table in such a case?

Any input/help will be highly appreciated.

Thank you,

Judy James "

*********************************************************************

Judy Rose James, Ph.D.

Clinical Physicist, MR Imaging Division

Assistant Professor, Department of Radiology

University of Mississippi Medical Center

Jackson, MS - 39216

Ph: (601) 984-2585; Pager: (601) 929-2442

Email: jjames2 at umc.edu

*********************************************************************

________________________________

From: mristudio-users-bounces at mristudio.org

[mristudio-users-bounces at mristudio.org] On Behalf Of Jacquie Hodge

[Jacquie.Hodge at albertahealthservices.ca]

Sent: Friday, April 08, 2011 11:56 AM

To: mristudio-users at mristudio.org

Subject: [Mristudio-users] Fa values

Good morning everyone,

I am using DTI studio for my project where I am interested in comparing the

left and right CST's in children who have suffereed injury in that area and

after reading many studies on DTI decided to compare average FA values of

the tracts as one of my variables. However, I have come across this questino

from one of my supervisors and cannot really answer it and am hoping for

your help/expertise.

Here is goes:

Is the FA value still a viable measure to look at and use to make a

correlation if you are using FA values to pull the white matter tract? It

seems like if the tract is made from FA values then you should not be able

to use the FA as an outcome variable. This question has come up as I

presented my research idea and I'm not sure how to answer it. Most studies

that use DTI use FA thresholds to pull the tracts and then also the FA

values (eg. mean FA) to make comparisons between the tracts.

I really hope that my question makes sense as I have found it very hard to

word properly.

Thank you very much,

Jacquie

Jacquie Hodge MSc candidate in Neuroscience, BSc

Neuroscience, University of Calgary

Research Assistant, Calgary Pediatric Stroke Program

Alberta Children's Hospital

2888 Shaganappi Trail NW, Calgary, AB, Canada T3B 6A8

Phone: 403-955-7733 Fax: 403-955-2922

jacquie.hodge at albertahealthservices.ca

Program website:

http://www.calgaryhealthregion.ca/programs/stroke/pediatric.htm

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On Feb 23, 2011, at 4:35 AM, susumu mori wrote:

Andreas is right.

So called ADC (average diffusion constant, apparent diffusion constant) and
MD (mean diffusivity) are obtained by trace/3 (trace divided by 3), while
the trace is (eigenvalue0+eigenvalue1+eigenvalue2).

also, axial diffusivity is same as eigenvalue0 and radial diffusivity is the
average of eigenvalue1 and 2 [ (eigenvalue1+eigenvalue2)/2].

On Wed, Feb 23, 2011 at 8:31 AM, Andreas Buchmann <buchmann2 at wisc.edu>
wrote:

Dear Yo,

I'm using trace diffusivity, which is strongly related to mean diffusivity
(I think, just multiplied with a constant factor, experts correct me if I'm
wrong).

Andreas

-----Original Message-----
From: mristudio-users-bounces at mristudio.org
[mailto:mristudio-users-bounces at mristudio.org] On Behalf Of

107310 at ib.k.u-tokyo.ac.jp
Sent: Dienstag, 22. Februar 2011 19:36
To: DTI Studio, ROI Editor, DiffeoMap Questions/Support
Subject: Re: [Mristudio-users] radial diffusivity, mean diffusivity

Dear Andreas, Ryuzo and DTI experts

I also try to calculate mean diffusivity.
But in DTI studio, only the radial diffusivity and ADCs can calculate at
the 'Image'-tab with ROI.

Is there any function to measure mean diffusivity?
Please give me any suggestion.

Many thanks.

YO

> Dear Andreas
>
>
>
> Thank you very much for your suggestion.  I will try.
>
>
>
> Ryuzo
>
>
>
> From: mristudio-users-bounces at mristudio.org
> [mailto:mristudio-users-bounces at mristudio.org] On Behalf Of Andreas
Buchmann
> Sent: Monday, February 21, 2011 11:03 PM
> To: 'DTI Studio, ROI Editor, DiffeoMap Questions/Support'
> Subject: Re: [Mristudio-users] radial diffusivity, mean diffusivity
>
>
>
> Dear Ryuzo,
>
>
>
> yes, you're on the right track with (1). After the estimation, DTI-
Studio
> appends the images to the list of images you have, and you can see
them
> under the 'Image'-tab and save them with right-click on the image.
>
>
>
> Good luck
>
> Andreas
>
>
>
>   _____
>
> From: mristudio-users-bounces at mristudio.org
> [mailto:mristudio-users-bounces at mristudio.org] On Behalf Of hanaie
> Sent: Montag, 21. Februar 2011 07:46
> To: mristudio-users at mristudio.org
> Subject: [Mristudio-users] radial diffusivity, mean diffusivity
>
>
>
> Dear DTI experts
>
>
>
> How can I do to obtain the radial diffusivity and mean diffusivity in
DTI
> studio?
>
>
>
> 1.     In the " Dti Map" tab, clicking "Tensor, color Map etc" button,
and
> checking the checkboxes "Radial", "Trace"
>
>
>
> 2.     After tensor calculation and fiber tracking, if I click "
statistics"
> button in the "Fiber" tab and
>
>  I choose the each image and click "go" button in the another window,
can I
> obtain radial and mean diffusivity?
>
>
>
>
>
> Please give me any suggestion.
>
>
>
> Many thanks.
>
>
>
> Ryuzo
>
>
>
>
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