There are a lot of reasons that the raw intensities might be higher on one
scanner than another, and none of those should matter in this case.
Martin's point about the trace images is a good one; I had encountered this
before but didn't think of it!
Peace,
Matt.
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
Of Martin Kavec
Sent: Sunday, April 05, 2009 3:53 PM
To: [log in to unmask]
Subject: Re: [FSL] What is the Problem with that DTI data?
Hi Markus,
On Sunday 05 April 2009 22:11:56 Markus Gschwind wrote:
> Hi Matt and Martin!
>
> Thanks for help!
>
> @Martin:
> I also have tried dcm2nii. But it does not give me the bvecs and bvals.
> They are .IMA files and come from PACS archive.
Your PACS is giving you a strange format!
Nevertheless, in this branch of problem solving I would make sure that the
image dataset does not include the trace-weighted images, which Philips
calculates if their diffusion encoding scheme is used. This image volume is
usually appended at the end of dataset I you can easily identify it, because
it looks like diffusion weighted but lacks any WM orientation dependent
contrast.
You can get the image slice rotation corrected bvecs by going on the
http://godzilla.kennedykrieger.org/~jfarrell/OTHERphilips/GUI.html
But for this to use you have to obtain all the information required. This
may
be difficult if your PACS is stripping away some private DICOM tags.
Best,
Martin
>
> @Matt
> This is the printscreen of both raw data (same patient, scanned in a
> distance of 4 days).
>
> Obviously the Philips data (attachment, on the right) have much higher
> intensity when scaled at the same 0:120 in fslview.
>
> Is this a reconstruction problem?
>
> Very grateful!
> Markus
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