If you don't do that rotation correction of the table you won't get
accurate results. If you look at the calculated water diffusion lines with
a rotated and unrotated table, you will see that the orientations change by
a fixed amount across the whole brain.
Peace,
Matt.
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
Of Xiaoxu Liu
Sent: Wednesday, March 05, 2008 12:46 PM
To: [log in to unmask]
Subject: [FSL] Will the gradient correction affect the probabilistic
tracking result?
Hi all,
I have collected a DTI data set on Siemens scanner using a 60-direction
MGH gradient scheme. The slice orientation is oblique that means the
physical coordinates of scanner are not the same with the imaging
coordinates. Some softwares (like trackvis) suggest to do the gradient
correction in this case, that is rotating the original gradient (in physical
coordinates for Siemens) to the image space. I noticed that some dicom
converter software will do this automatically.
My question is: do we really need this gradient correction? and will this
gradient correction affect the probabilistic tracking results? will this
affect the tensor calculation? Sorry if this topic has been discussed
before. I did a search in this archive but I didn't find anything. Thanks!
Xiaoxu
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