[Mristudio-users] ADC-Map Calculation in DTIStudio

Mon Aug 15 18:49:50 EDT 2011

Hi Rachael,

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.

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.

The "mean diffusivity" is calculated from the average of the three
eigenvalues. Therefore, we can get only after the tensor calculation.

I hope this clarify your question.

Susumu

On Mon, Aug 15, 2011 at 6:31 PM, Rachael Gonzales <rachaelg.uh at gmail.com>wrote:

> 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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>> > mristudio-users at mristudio.org
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>> >
>>
>>
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