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Saad,

thank you very much  - that worked!

Cheers,

Kristin

From: Saad Jbabdi <[log in to unmask]<mailto:[log in to unmask]>>
Reply-To: FSL - FMRIB's Software Library <[log in to unmask]<mailto:[log in to unmask]>>
Date: Wednesday, 7 May 2014 10:05
To: "[log in to unmask]<mailto:[log in to unmask]>" <[log in to unmask]<mailto:[log in to unmask]>>
Subject: Re: [FSL] Calculating FA from tract in subject T1 space

Hi
You can transform the fdt_paths file onto diffusion space using either flirt or applywarp (command line) or ApplyXFM (GUI).

Then you might need to threshold/binarise your result (with fslmaths) before you feed it to fslstats.

Cheers
Saad.


On 6 May 2014, at 19:42, Kristin Koller <[log in to unmask]<mailto:[log in to unmask]>> wrote:

Dear FSL,

I am running DTI tractography in FSL by drawing masks on the subject's T1 brain, and using the "seed space is not diffusion" option in the FDT gui . After I select the T1-to-diffusion space transform .mat file and click go, the output is a tract that fits well on the subject's T1 brain. However, when I try to calculate/extract the mean Fractional Anisotropy (FA) value of the tract from the FA map (dti_FA.nii.gz), there is an error as the resulting tract is not in the same space as the FA map (FA is in diffusion).

When registering the tract to diffusion space using SPM, the resulting tract fits well on the FA brain. However, when I calculate the mean FA of the tract (using fslstats dti_FA.nii.gz -k fdt_paths.nii.gz -M), I still get the following error:

ERROR:: Empty mask image
0.000000

Is there a way to best register/transform the tract back to diffusion space and calculate FA? Or is it best to stick to tractography in diffusion space for the purposes of calculating FA?

Any advice is much appreciated!

Kind regards,

Kristin Koller




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--
Saad Jbabdi
University of Oxford, FMRIB Centre

JR Hospital, Headington, OX3 9DU, UK
(+44)1865-222466  (fax 717)
www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi<http://www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi>




Rhif Elusen Gofrestredig 1141565 - Registered Charity No. 1141565

Gall y neges e-bost hon, ac unrhyw atodiadau a anfonwyd gyda hi, gynnwys deunydd cyfrinachol ac wedi eu bwriadu i'w defnyddio'n unig gan y sawl y cawsant eu cyfeirio ato (atynt). Os ydych wedi derbyn y neges e-bost hon trwy gamgymeriad, rhowch wybod i'r anfonwr ar unwaith a dilewch y neges. Os na fwriadwyd anfon y neges atoch chi, rhaid i chi beidio a defnyddio, cadw neu ddatgelu unrhyw wybodaeth a gynhwysir ynddi. Mae unrhyw farn neu safbwynt yn eiddo i'r sawl a'i hanfonodd yn unig ac nid yw o anghenraid yn cynrychioli barn Prifysgol Bangor. Nid yw Prifysgol Bangor yn gwarantu bod y neges e-bost hon neu unrhyw atodiadau yn rhydd rhag firysau neu 100% yn ddiogel. Oni bai fod hyn wedi ei ddatgan yn uniongyrchol yn nhestun yr e-bost, nid bwriad y neges e-bost hon yw ffurfio contract rhwymol - mae rhestr o lofnodwyr awdurdodedig ar gael o Swyddfa Cyllid Prifysgol Bangor.

This email and any attachments may contain confidential material and is solely for the use of the intended recipient(s). If you have received this email in error, please notify the sender immediately and delete this email. If you are not the intended recipient(s), you must not use, retain or disclose any information contained in this email. Any views or opinions are solely those of the sender and do not necessarily represent those of Bangor University. Bangor University does not guarantee that this email or any attachments are free from viruses or 100% secure. Unless expressly stated in the body of the text of the email, this email is not intended to form a binding contract - a list of authorised signatories is available from the Bangor University Finance Office.