[Mristudio-users] non isometric voxels (susumu)

[mustela at mce.hggm.es]

Thank you for your suggestions!
regards,

Santiago

At 00:19 06/08/2008, you wrote:
>Date: Tue, 05 Aug 2008 18:19:44 -0400
>From: susumu <susumu at mri.jhu.edu>
>Subject: Re: [Mristudio-users] non isometric voxels
>To: "'DTI Studio, ROI Editor,   Landmarker Questions/Support'"
>         <mristudio-users at mristudio.org>
>Message-ID: <73alti$380opl at ipex2.johnshopkins.edu>
>Content-Type: text/plain; charset="iso-8859-1"
>
>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
>
> ><((((?>`?.??.???`?.?.???`?...?><((((?>`?.??.???`?.?.???`?...?><((((?>
>   `?.??.???`?.?.???`?...?><((((?>`?.??.???`?.?.???`?...?><((((?>`?.??.??
>Santiago Reig
>     Hospital General Universitario Gregorio Mara??n
>     Unidad de Medicina y Cirug?a 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