[Mrtrix-discussion] question about CSD

[Olivier.Salvado at csiro.au]

Randal Moldrich ([r.moldrich at uq.edu.au]) of QBI at UQ did a study to investigate the sensitivity of tractography to different parameters including resolution and anisotropy I think. He presented to the Brisbane Imaging group a few months ago. This was the abstract of his talk:


Tomorrow's seminar will be given by Randal Moldrich of QBI

Title:
Accelerating diffusion-weighted imaging for ex vivo studies of mouse
brain

Abstract:
High-field strength magnets, high angular resolution diffusion
imaging
and multi-vector tracking models have greatly advanced our
visualisation of white matter tracts in the human and mouse brain.
For
imaging mouse models of human disease, there remain three technical
challenges: tractography modelling, acquisition time, and generation
of diffusion-weighted imaging (DWI) in vivo. At present we are
assessing encoding and other acceleration options for reducing spin
echo DWI acquisition time, including resolution, partial Fourier
transform and zero filling. We are validating the acceleration
protocols using adult mice deficient for the cortical patterning
gene
Fgf17, which have subtly reduced frontocortical projections.

The seminar will be held at 11am in the Level 7 seminar room, QBI, St
Lucia campus. All welcome.



Olivier
____________________
Olivier Salvado, PhD
Group  Leader | Biomedical Imaging
ICT, The Australian e-Health Research Centre
CSIRO
Phone: +61 7 3253 3658 | Mobile: +61 4 03 88 22 49 
olivier.salvado at csiro.au | www.csiro.au | http://www.aehrc.com/biomedical_imaging/
Address: level 5 UQ Health Science Building 901/16 UQCCR building, Royal Brisbane and Women's Hospital, Herston, QLD, 4029

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-----Original Message-----
From: mrtrix-discussion-bounces at www.nitrc.org [mailto:mrtrix-discussion-bounces at www.nitrc.org] On Behalf Of Donald Tournier
Sent: Monday, 18 January 2010 14:30
To: Michael Zeineh
Cc: mrtrix-discussion at www.nitrc.org
Subject: Re: [Mrtrix-discussion] question about CSD

Hi Michael,

Actually, I would have thought it would be the opposite: a structure
entirely through plane would be resolved better. That said, I can't
think of any studies that have looked at that specifically, so don't
quote me on that... Maybe someone else on the list can suggest an
appropriate reference...?

Cheers,

Donald.


2010/1/18 Michael Zeineh <mmzeineh at gmail.com>:
> Thank you Donald.
>
> I see. So, for the example an axial DTI with thick slices but small in
> plane voxels, a structure entirely in-plane would be resolved better
> than if the same object were entirely through-plane (assuming things
> like SNR are similar).
>
> Michael
>
> On Sun, Jan 17, 2010 at 3:18 PM, Donald Tournier
> <d.tournier at brain.org.au> wrote:
>> Hi Michael,
>>
>> Yes, it should work with anisotropic voxels (although isotropic would
>> always be recommended). There is little point interpolating (at least
>> not using linear interpolation), since the tracking code performs
>> linear interpolation while tracking. In terms of bias, the
>> orientations are provided with respect to real (scanner) coordinates,
>> so do not depend on the voxel dimensions. There would however be a
>> bias when tracking WM structures oriented predominantly through-plane
>> versus in-plane, since the "effective resolution" would be higher in
>> the first case. This applies to all tracking methods though, not just
>> MRtrix (and is not a limitation of the CSD itself).
>>
>> Hope that helps,
>>
>> Donald.
>>
>>
>> 2010/1/16 Michael Zeineh <mmzeineh at gmail.com>:
>>> Out of curiosity, will it work on anisotropic diffusion data (i.e.
>>> voxels are thicker along one axis)? If so, would there be any expected
>>> errors or biases? Would simple interpolation (somewhat) resolve those
>>> issues?
>>>
>>> Thank you,
>>> Michael
>>> _______________________________________________
>>> Mrtrix-discussion mailing list
>>> Mrtrix-discussion at www.nitrc.org
>>> http://www.nitrc.org/mailman/listinfo/mrtrix-discussion
>>>
>>
>>
>>
>> --
>> Jacques-Donald Tournier (PhD)
>> Brain Research Institute, Melbourne, Australia
>> Tel: +61 (0)3 9496 4078
>>
>



-- 
Jacques-Donald Tournier (PhD)
Brain Research Institute, Melbourne, Australia
Tel: +61 (0)3 9496 4078
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