[Mristudio-users] non isometric voxels

[susumu]

It is difficult to set a threshold and say, "you can do tractography if your
pixel size is like this". Of course, isotropic resolution is better than
anisotropic pixels in general, but if the fiber of your interest has a
tubular shape along the longest axis of the anisotropy pixel (e.g. the
corticospinal tract + axial imaging), then you do not have much partial
volume problem. On the other hand, you'd have irreproducible results for the
corpus callosum reconstruction with 5 mm axial slice. If you do tractography
for all subjects and get reproducible results, you may be able to use the
data.

 

  _____  

From: mristudio-users-bounces at mristudio.org
[mailto:mristudio-users-bounces at mristudio.org] On Behalf Of Jun Yi Wang
Sent: Tuesday, August 05, 2008 9:55 AM
To: DTI Studio, ROI Editor, Landmarker Questions/Support
Subject: Re: [Mristudio-users] non isometric voxels

 

Hi Santiago,

 

We also have DTI images with 1x1x5 mm voxel size.  We tried tractography
using DTI Studio, but the fibers fell to propagate to next slices.  I don't
know whether reslicing to thinner slices will help or not.  But even it
works, the quality of the tractography will not be good.

 

Jun Yi Wang

Predoc., University of Texas at Dallas

Research assistant, University of Texast Southwestern Medical Center

 

----- Original Message ----
From: "mustela at mce.hggm.es" <mustela at mce.hggm.es>
To: mristudio-users at mristudio.org
Sent: Monday, August 4, 2008 1:30:53 PM
Subject: [Mristudio-users] non isometric voxels

Hi,

I wonder if someone has experience in DTI analysis using scans from a 
1.5 GE Signa. The problem is that images were acquired for 33 
directions but with a pixel size of 1.1 x 1.1 x 5 mm  (x,y,z) aquired 
in axial (x,y) plane. Far for being isometric, as recommended by the
experts...

Before doing all the preprocessing, do you think that those images 
would be too noisy for tracktography or FA analysis??
The data is intended to investigate group comparison patients 
/controls using ADC and RA values, and sample size is not very large.

Thanks in advance,

Santiago

><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>
  `·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´
Santiago Reig
    Hospital General Universitario Gregorio Marañón
    Unidad de Medicina y Cirugía Experimental
    c/ Dr. Esquerdo 46, 28007 Madrid
          Tel:  34 91 426 5067 Fax: 34 91 426 5108
mustela at mce.hggm.es  http://www.hggm.es/image  

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