Hi Rachael,<div><br></div><div>Sorry for the confusion, but the "mean" in DtiStudio is NOT the "mean diffusivity (MD)" widely used in the field. Hangyi, we should change the name.</div><div><br></div><div>
The "mean" in DtiStudio is the mean of individual ADC maps. For example, if we use a 12-orientation method, it is possible to calculate ADC of the first gradient orientation. Likewise, ADC of the second, third, and up to the 12th gradient orientations can be calculated. Then, you can get 12 ADCs. The "mean" in this case is the average of the 12 ADCs. </div>
<div><br></div><div>The "mean diffusivity" is calculated from the average of the three eigenvalues. Therefore, we can get only after the tensor calculation.</div><div><br></div><div>I hope this clarify your question.</div>
<div><br></div><div>Susumu<br><br><div class="gmail_quote">On Mon, Aug 15, 2011 at 6:31 PM, Rachael Gonzales <span dir="ltr"><<a href="mailto:rachaelg.uh@gmail.com">rachaelg.uh@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="word-wrap:break-word">Hi DTI experts,<div><br></div><div>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 <b>apparent </b>or <b>average</b> diffusion coefficient? </div>
<div><br></div><div><br></div><div>Thanks,</div><div><br></div><div>Rachael</div><div><br></div><div><div style="font-family:Tahoma"><br></div></div><div>*****************************************************************************************************************************</div>
<div><br></div><div>Judy, in DtiStudio, ADC (or also called MD) should be obtained from "Trace".<br><br>Trace is defined as Dxx+Dyy+Dzz. If you divide it by 3, it becomes<br>"Average diffusion constant (ADC)" or "Mean diffusivity (MD)". We like<br>
to use the term "trace" because it has clear mathematical definition<br>while ADC is also used for "Apparent diffusion constant", which has a<br>different meaning from "average diffusion constant".<br>
<br>On Mon, Apr 11, 2011 at 11:58 AM, Judy James <<a href="mailto:jjames2@umc.edu" target="_blank">jjames2@umc.edu</a>> wrote:<br><blockquote type="cite">Is any one in this group aware of how to calculate ADC maps from the<br>
</blockquote><blockquote type="cite">original DWI images in DTI studio - not DTI images, like how to set the<br></blockquote><blockquote type="cite">gradient table in such a case?<br></blockquote><blockquote type="cite">Any input/help will be highly appreciated.<br>
</blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Thank you,<br></blockquote><blockquote type="cite">Judy James "<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">
<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">*********************************************************************<br></blockquote><blockquote type="cite">Judy Rose James, Ph.D.<br></blockquote>
<blockquote type="cite">Clinical Physicist, MR Imaging Division<br></blockquote><blockquote type="cite">Assistant Professor, Department of Radiology<br></blockquote><blockquote type="cite">University of Mississippi Medical Center<br>
</blockquote><blockquote type="cite">Jackson, MS - 39216<br></blockquote><blockquote type="cite">Ph: <a href="tel:%28601%29%20984-2585" value="+16019842585" target="_blank">(601) 984-2585</a>; Pager: <a href="tel:%28601%29%20929-2442" value="+16019292442" target="_blank">(601) 929-2442</a><br>
</blockquote><blockquote type="cite">Email: <a href="mailto:jjames2@umc.edu" target="_blank">jjames2@umc.edu</a><br></blockquote><blockquote type="cite">*********************************************************************<br>
</blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">________________________________<br></blockquote><blockquote type="cite">From: <a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a><br>
</blockquote><blockquote type="cite">[<a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a>] On Behalf Of Jacquie Hodge<br></blockquote><blockquote type="cite">[<a href="mailto:Jacquie.Hodge@albertahealthservices.ca" target="_blank">Jacquie.Hodge@albertahealthservices.ca</a>]<br>
</blockquote><blockquote type="cite">Sent: Friday, April 08, 2011 11:56 AM<br></blockquote><blockquote type="cite">To: <a href="mailto:mristudio-users@mristudio.org" target="_blank">mristudio-users@mristudio.org</a><br></blockquote>
<blockquote type="cite">Subject: [Mristudio-users] Fa values<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Good morning everyone,<br></blockquote><blockquote type="cite"><br></blockquote>
<blockquote type="cite">I am using DTI studio for my project where I am interested in comparing the<br></blockquote><blockquote type="cite">left and right CST's in children who have suffereed injury in that area and<br>
</blockquote><blockquote type="cite">after reading many studies on DTI decided to compare average FA values of<br></blockquote><blockquote type="cite">the tracts as one of my variables. However, I have come across this questino<br>
</blockquote><blockquote type="cite">from one of my supervisors and cannot really answer it and am hoping for<br></blockquote><blockquote type="cite">your help/expertise.<br></blockquote><blockquote type="cite">Here is goes:<br>
</blockquote><blockquote type="cite">Is the FA value still a viable measure to look at and use to make a<br></blockquote><blockquote type="cite">correlation if you are using FA values to pull the white matter tract? It<br>
</blockquote><blockquote type="cite">seems like if the tract is made from FA values then you should not be able<br></blockquote><blockquote type="cite">to use the FA as an outcome variable. This question has come up as I<br>
</blockquote><blockquote type="cite">presented my research idea and I'm not sure how to answer it. Most studies<br></blockquote><blockquote type="cite">that use DTI use FA thresholds to pull the tracts and then also the FA<br>
</blockquote><blockquote type="cite">values (eg. mean FA) to make comparisons between the tracts.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I really hope that my question makes sense as I have found it very hard to<br>
</blockquote><blockquote type="cite">word properly.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Thank you very much,<br></blockquote><blockquote type="cite">Jacquie<br></blockquote><blockquote type="cite">
<br></blockquote><blockquote type="cite">Jacquie Hodge MSc candidate in Neuroscience, BSc<br></blockquote><blockquote type="cite">Neuroscience, University of Calgary<br></blockquote><blockquote type="cite">Research Assistant, Calgary Pediatric Stroke Program<br>
</blockquote><blockquote type="cite">Alberta Children's Hospital<br></blockquote><blockquote type="cite">2888 Shaganappi Trail NW, Calgary, AB, Canada T3B 6A8<br></blockquote><blockquote type="cite">Phone: <a href="tel:403-955-7733" value="+14039557733" target="_blank">403-955-7733</a> Fax: <a href="tel:403-955-2922" value="+14039552922" target="_blank">403-955-2922</a><br>
</blockquote><blockquote type="cite"><a href="mailto:jacquie.hodge@albertahealthservices.ca" target="_blank">jacquie.hodge@albertahealthservices.ca</a><br></blockquote><blockquote type="cite">Program website:<br></blockquote>
<blockquote type="cite"><a href="http://www.calgaryhealthregion.ca/programs/stroke/pediatric.htm" target="_blank">http://www.calgaryhealthregion.ca/programs/stroke/pediatric.htm</a><br></blockquote><blockquote type="cite">
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<br><div><div>On Feb 23, 2011, at 4:35 AM, susumu mori wrote:</div><br><blockquote type="cite">Andreas is right.<div>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).</div>
<div><br></div><div>also, axial diffusivity is same as eigenvalue0 and radial diffusivity is the average of eigenvalue1 and 2 [ (eigenvalue1+eigenvalue2)/2].<br><br><div class="gmail_quote">On Wed, Feb 23, 2011 at 8:31 AM, Andreas Buchmann <span dir="ltr"><<a href="mailto:buchmann2@wisc.edu" target="_blank">buchmann2@wisc.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear Yo,<br>
<br>
I'm using trace diffusivity, which is strongly related to mean diffusivity<br>
(I think, just multiplied with a constant factor, experts correct me if I'm<br>
wrong).<br>
<font color="#888888"><br>
Andreas<br>
</font><div><br>
<br>
<br>
-----Original Message-----<br>
From: <a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a><br>
[mailto:<a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a>] On Behalf Of<br>
</div><div><div></div><div><a href="mailto:107310@ib.k.u-tokyo.ac.jp" target="_blank">107310@ib.k.u-tokyo.ac.jp</a><br>
Sent: Dienstag, 22. Februar 2011 19:36<br>
To: DTI Studio, ROI Editor, DiffeoMap Questions/Support<br>
Subject: Re: [Mristudio-users] radial diffusivity, mean diffusivity<br>
<br>
Dear Andreas, Ryuzo and DTI experts<br>
<br>
<br>
I also try to calculate mean diffusivity.<br>
But in DTI studio, only the radial diffusivity and ADCs can calculate at<br>
the 'Image'-tab with ROI.<br>
<br>
Is there any function to measure mean diffusivity?<br>
Please give me any suggestion.<br>
<br>
Many thanks.<br>
<br>
<br>
YO<br>
<br>
<br>
> Dear Andreas<br>
><br>
><br>
><br>
> Thank you very much for your suggestion. I will try.<br>
><br>
><br>
><br>
> Ryuzo<br>
><br>
><br>
><br>
> From: <a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a><br>
> [mailto:<a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a>] On Behalf Of Andreas<br>
Buchmann<br>
> Sent: Monday, February 21, 2011 11:03 PM<br>
> To: 'DTI Studio, ROI Editor, DiffeoMap Questions/Support'<br>
> Subject: Re: [Mristudio-users] radial diffusivity, mean diffusivity<br>
><br>
><br>
><br>
> Dear Ryuzo,<br>
><br>
><br>
><br>
> yes, you're on the right track with (1). After the estimation, DTI-<br>
Studio<br>
> appends the images to the list of images you have, and you can see<br>
them<br>
> under the 'Image'-tab and save them with right-click on the image.<br>
><br>
><br>
><br>
> Good luck<br>
><br>
> Andreas<br>
><br>
><br>
><br>
> _____<br>
><br>
> From: <a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a><br>
> [mailto:<a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a>] On Behalf Of hanaie<br>
> Sent: Montag, 21. Februar 2011 07:46<br>
> To: <a href="mailto:mristudio-users@mristudio.org" target="_blank">mristudio-users@mristudio.org</a><br>
> Subject: [Mristudio-users] radial diffusivity, mean diffusivity<br>
><br>
><br>
><br>
> Dear DTI experts<br>
><br>
><br>
><br>
> How can I do to obtain the radial diffusivity and mean diffusivity in<br>
DTI<br>
> studio?<br>
><br>
><br>
><br>
> 1. In the " Dti Map" tab, clicking "Tensor, color Map etc" button,<br>
and<br>
> checking the checkboxes "Radial", "Trace"<br>
><br>
><br>
><br>
> 2. After tensor calculation and fiber tracking, if I click "<br>
statistics"<br>
> button in the "Fiber" tab and<br>
><br>
> I choose the each image and click "go" button in the another window,<br>
can I<br>
> obtain radial and mean diffusivity?<br>
><br>
><br>
><br>
><br>
><br>
> Please give me any suggestion.<br>
><br>
><br>
><br>
> Many thanks.<br>
><br>
><br>
><br>
> Ryuzo<br>
><br>
><br>
><br>
><br>
> _______________________________________________<br>
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