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
_______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
