The T-SPOON paper in NeuroImage may give you some ideas about how to
look at ADC or FA values in WM.
Jee Eun Lee, Moo K. Chung, Mariana Lazar, Molly B. DuBray, Jinsuh Kim,
Erin D. Bigler, Janet E. Lainhart, Andrew L. Alexander. A study of
diffusion tensor imaging by tissue-specific, smoothing-compensated
voxel-based analysis. NeuroImage, Volume 44, Issue 3, 1 February 2009,
Pages 870-883
Various co-workers of mine use an extension of this approach that
weights the values with Jacobian scaled WM (or GM), rather than just
WM. Off the top of my head, I'm not sure where the best place to find
a description of this would be. It may be in a recent quantitative
imaging paper by Bogdan Draganski, or maybe in a recent paper on
cortical thickness mapping by Chloe Hutton.
Best regards,
-John
On 20 November 2011 18:31, Jeff Browndyke <[log in to unmask]> wrote:
> Just a quick follow up...
> Does the same non-modulation ("preserves volumes") of VBM8/DARTEL transforms
> hold for ADC and FA maps, as well?
> Thanks,
> Jeff
> On Nov 16, 2011, at 9:31 PM, Jeff Browndyke wrote:
>
>
> No, you don't want to apply jacobian modulation to BOLD and ASL data.
>
> cheers,
>
> -MH
>
> On Wed, 2011-11-16 at 14:51 -0500, Jeff Browndyke wrote:
>
> Thank you for the input, Roberto.
>
> Thought it might be o.k., but wanted to double-check before tying up
> processing resources for a couple of days.
>
> Am I correct about the "preserve volumes" (modulation) option, as it applies
> to preserving EPI and ASL concentrations after high dimensional warping?
> The VBM8 deformations routine does not provide any guidance on the matter
> and is clearly written with the assumption that the images being transformed
> are structural.
>
> Warm regards,
>
> Jeff
>
>
> ---- [log in to unmask] wrote:
>
> Dear Jeff,
>
> I have VBM8 segmented (w/ DARTEL high-dimensional warp and
>
> non-linear modulation of grey and white maps) a large group of
>
> structural images that also have co-registered ASL and EPI series
>
> images and in the same voxel dimensions.
>
> Any problems in applying the forward transforms to the ASL and EPI
>
> data to bring them into atlas space?
>
> Having carried out several studies with ASL, I could not see a
>
> systematic difference between using the strategy you describe or
>
> normalizing the EPI average to the EPI template when I looked at it. I
>
> think both are acceptable. I also think that there is no ASL-specific
>
> issue here to consider.
>
> Best wishes,
>
> Roberto Viviani
>
> Department of Psychiatry, University of Ulm
>
>
>
>
>
> -----------------------------------------------------------------------
> Jeff Browndyke, Ph.D.
> Clinical & Research Neuropsychologist
> Durham VA & Duke University Medical Centers
>
> [log in to unmask] / [log in to unmask]
> office: (919) 286-0411 ext. 4656
> cell: (336) 264-4222
>
> -----------------------------------------------------------------------
> Jeff Browndyke, Ph.D.
> Clinical & Research Neuropsychologist
> Durham VA & Duke University Medical Centers
> [log in to unmask] / [log in to unmask]
> office: (919) 286-0411 ext. 4656
> cell: (336) 264-4222
>
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