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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>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.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
mristudio-users-bounces@mristudio.org
[mailto:mristudio-users-bounces@mristudio.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Jun Yi Wang<br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, August 05, 2008
9:55 AM<br>
<b><span style='font-weight:bold'>To:</span></b> DTI Studio, ROI Editor,
Landmarker Questions/Support<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Mristudio-users] non
isometric voxels</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hi <st1:City w:st="on"><st1:place w:st="on">Santiago</st1:place></st1:City>,<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>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.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Jun Yi Wang<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Predoc., <st1:PlaceType w:st="on">University</st1:PlaceType> of <st1:PlaceName
w:st="on">Texas</st1:PlaceName> at <st1:City w:st="on"><st1:place w:st="on">Dallas</st1:place></st1:City><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Research assistant, University of Texast Southwestern Medical Center<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>----- Original Message ----<br>
From: "mustela@mce.hggm.es" <mustela@mce.hggm.es><br>
To: <st1:PersonName w:st="on">mristudio-users@mristudio.org</st1:PersonName><br>
Sent: Monday, August 4, 2008 1:30:53 PM<br>
Subject: [Mristudio-users] non isometric voxels<br>
<br>
Hi,<br>
<br>
I wonder if someone has experience in DTI analysis using scans from a <br>
1.5 GE Signa. The problem is that images were acquired for 33 <br>
directions but with a pixel size of 1.1 x 1.1 x 5 mm (x,y,z) aquired <br>
in axial (x,y) plane. Far for being isometric, as recommended by the experts...<br>
<br>
Before doing all the preprocessing, do you think that those images <br>
would be too noisy for tracktography or FA analysis??<br>
The data is intended to investigate group comparison patients <br>
/controls using ADC and RA values, and sample size is not very large.<br>
<br>
Thanks in advance,<br>
<br>
<st1:City w:st="on"><st1:place w:st="on">Santiago</st1:place></st1:City><br>
<br>
><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º><br>
`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´<br>
<st1:City w:st="on"><st1:place w:st="on">Santiago</st1:place></st1:City> Reig<br>
Hospital General Universitario Gregorio Marañón<br>
Unidad de Medicina y Cirugía Experimental<br>
c/ Dr. Esquerdo 46, 28007 <st1:State w:st="on"><st1:place w:st="on">Madrid</st1:place></st1:State><br>
Tel: 34 91 426 5067 Fax: 34 91 426
5108<br>
<a href="mailto:mustela@mce.hggm.es" ymailto="mailto:mustela@mce.hggm.es">mustela@mce.hggm.es</a>
<a href="http://www.hggm.es/image" target="_blank">http://www.hggm.es/image</a>
<br>
<br>
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ymailto="mailto:Mristudio-users@mristudio.org">Mristudio-users@mristudio.org</a><br>
<a href="http://lists.mristudio.org/mailman/listinfo/mristudio-users"
target="_blank">http://lists.mristudio.org/mailman/listinfo/mristudio-users</a><o:p></o:p></span></font></p>
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