thank you ________________________________________ Von: Anastasia Yendiki [ayendiki@nmr.mgh.harvard.edu] Gesendet: Sonntag, 12. Januar 2014 03:10 An: Roschinski, Benjamin Cc: freesurfer@nmr.mgh.harvard.edu; gerit.pfuhl@gmail.com Betreff: Re: b value for TRACULA
Hi Benjamin - The ball-and-stick model doesn't require b-values in the tens of thousands, that would be for DSI type acquisitions.
a.y
On Sat, 11 Jan 2014, Roschinski, Benjamin wrote:
Dear Anastasia,
in the FS Tutorial/Running Freesurfer you say TRACULA uses bedpostX to fit the ball-and-stick model to the DWI data. So with TRACULA we use a high angular resolution diffusion imaging model and you give the recommendation in "Introduction to diffusion MRI" to set the b value for HARDI ~ 10,000 sec/mm² with a few of 100´s of gradient directions. The b values in your published articles are much less than what you adviced and you also used much less gradient directions. What does it mean? Why do you suggest a higher b value although you use a much less one? Is it because of the upper likelihood of motion effects and the longer scan time or did I misunderstand the relationship between TRACULA and HARDI?
kind regards Benjamin
AG Ehrlich Medizinische Fakultät Carl Gustav Carus TU Dresden
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