In general one wants to get as many gradient directions as possible. Perhaps Mike knows the answer to your other question.
Matt. On 9/28/17, 2:59 AM, "[email protected] on behalf of Jeffrey Spielberg" <[email protected] on behalf of [email protected]> wrote: >Hi all, > >I¹m interested in setting up a diffusion protocol similar to the CCF >protocol and have two questions. First, what¹s the difference between >the dir98 and dir99 acquisitions (beyond having different vectors)? It >looks like both sample on 2 shells, use the same b-values, and have about >50:50 vectors on each shell, so I¹m not clear on why both are needed. > >Second, I was playing around with the Caruyer q-space sampling tool and >noticed that the output differs from the vectors provided as part of the >CCF protocol. Specifically, for dir98, they match for 1 shell, but the >vector magnitudes in the other shell have been shortened to .7071. My >guess is that this is necessary to tell the scanner to use the second >b-value (e.g., 1500). Is that correct? > >Best, >Jeff > > > >-- >Jeffrey M. Spielberg, Ph.D. >Assistant Professor, Clinical Science >Department of Psychological and Brain Sciences >University of Delaware >Newark, DE 19716 > >Office: 307 McKinly Laboratory >Lab: Suite 405 Wolf Hall >Phone: 302.831.7078 >Email: [email protected]<mailto:[email protected]> >Website: http://sites.udel.edu/jmsp/ > > >_______________________________________________ >HCP-Users mailing list >[email protected] >http://lists.humanconnectome.org/mailman/listinfo/hcp-users _______________________________________________ HCP-Users mailing list [email protected] http://lists.humanconnectome.org/mailman/listinfo/hcp-users
