Aga,
To avoid on scanner averaging you need to acquire the DTI data in multiple
one average scans, which produces multiple datasets that you then motion
correct (eddy_correct) and average. If you scanned four averages you would
have 13X4 volumes, however each scan would likely have its own directory.
Peace,
Matt.
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
Of Agnieszka Burzynska
Sent: Monday, August 27, 2007 12:26 PM
To: [log in to unmask]
Subject: [FSL] On-scanner averaging
Dear all,
How can I know if my data is averaged on scanner?
I am working on 1.5T Siemens Sonata, I convert my DICOMs using MRIconvert to
4D nifti format. The file I get (before eddy_correct) has just 13 volumes
(1xb=0 and 12xb=1000), although my NEX is 4.
According to the TBSS-related paper (Smith et al., Nat Prot, March 2007) one
should avoid on-scanner averaging. Does it mean that after data conversion I
should get a file with 13x4 volumes (if I have 12 DW grad directions and 4
NEX), then eddy_correct them and average images with the same gradient
direction before brain mask creation?
Thank you for any suggestion,
Best,
Aga
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