Hi,
yep - it's part of the book. The underlying Bayesian formulas were taken out in the editing process, however. We have not made it - due to time constraints - to seperately publish it in a journal but will hopefully do this year.
Anyway - it's not such a big deal: as described previously in the list, the waytotal i) depends on the prior that you know the tract is there (in the particular individual examined) and ii) does not alter the spatial extent of fdt_path itself but simply scales the values. Later, by thresholding you set a cutoff that impacts the spatial extent of the tract.
So you have to ascertain prior to the tractography (!) and by other, e.g. clinical means, that you can be sure that the tract is there and you have to decide if you consider scaling by the waytotal appropriate prior to thresholding.
Is it the spatial extent of the tract you are after, or some symmetry analysis, or the probability values themselves?
Cheers-
Andreas
________________________________________
Von: FSL - FMRIB's Software Library [[log in to unmask]] im Auftrag von Matt Glasser [[log in to unmask]]
Gesendet: Freitag, 15. Januar 2010 23:12
An: [log in to unmask]
Betreff: Re: [FSL] Publications normalizing tractography using waytotal
Hi Kristen,
I have not published any papers with this method yet, but Andreas Bartsch
may have. I know the method is described in Heidi and Tim's book, in
Andreas's chapter (19). The book (or at least part of it) is on Google
books:
http://books.google.com/books?hl=en&lr=lang_en&id=N20nnxByjVAC&oi=fnd&pg=PT9
&dq=Diffusion+MRI+from+quantitative+measurement+to+in+vivo+neuroanatomy&ots=
FTIbmZwxe3&sig=f8ySrMDRvk3gKbSvvVcZWX6ftik#v=onepage&q=&f=false
Peace,
Matt.
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
Of Kristen Lindgren
Sent: Friday, January 15, 2010 4:00 PM
To: [log in to unmask]
Subject: [FSL] Publications normalizing tractography using waytotal
Hello. This question may be best answered by Matt Glasser, but I'm
wondering if anyone is aware of a publication using probabilistic
tractography and normalizing the results using the waytotal values. I'd be
especially interested in ones looking at the arcuate fasciculus. Way back
when when I was working on my thesis, Matt said that he was using this in
his studies, but I'm not sure if he or any others have published using this
method. I'm working on submitting my DTI paper and would love to have
something more than "personal communication" to site when describing my
method. Any thoughts or help is appreciated. Thanks in advance!
Kristen
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