Re: [HCP-Users] fat suppression and diffusion scans

[Harms, Michael]

Hi Mark, The locked sequences that we are using for HCP, and on which those protocol print-outs are based, are based on a fairly old (at this point) version of the CMRR sequences, for which Fatsat = "none" actually means that a gradient reversal based method of fat suppression is used rather than RF pulses. Subsequently at some point in the MB sequence development, this "Grad. rev. fat suppr." option was explicitly added as its own variable to the UI, rather than implicitly invoked by Fatsat = "none".  I assume that you will be using the current version of the publicly available MB sequences (R012b), which includes this "Grad. rev. fat suppr." option. So, if you are implementing a Prisma protocol, you should also cross-referencing your parameter choices against the LifeSpan protocol for the 3T Prisma at CMRR, which you can find here: http://lifespan.humanconnectome.org/data/LSCMRR_3T_printout_2014.08.15.pdf In that, you will see that Fat suppr. = None Grad. rev. fat suppr. = Enabled The combination of those settings will match what is occurring "under the hood" for the HCP scans (and obviously will match what we are using for the LifeSpan 3T Prisma acquisitions). Give those settings a try, and see if they eliminate your fat artifacts. BTW: The reason that we use the gradient reversal rather than RF pulses is that you get a small improvement on the SAR front. cheers, -MH --  Michael Harms, Ph.D. ----------------------------------------------------------- Conte Center for the Neuroscience of Mental Disorders Washington University School of Medicine Department of Psychiatry, Box 8134 660 South Euclid Ave. Tel: 314-747-6173 St. Louis, MO  63110 Email: mha...@wustl.edu From: "Mark A. Pinsk" <mpi...@gmail.com> Date: Thursday, July 9, 2015 12:50 PM To: "hcp-users@humanconnectome.org" <hcp-users@humanconnectome.org> Subject: [HCP-Users] fat suppression and diffusion scans Hi  We've set up a diffusion protocol at our Prisma following HCP recommendations in Q3_Appendix_I. I noticed that you leave fat suppression turned off, and I'm curious if there's a reason for that?   From my initial scans this morning, we get prominent fat artifacts at b=3000, which seem to go away if we turn on "strong" fat suppression.   (I didn't get a chance to test the other fat supp methods (weak fatsat, SPAIR, water excite)). Just wanted to check in before I leave strong fat sat turned on in our protocol as a default. thanks! Mark _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users   The materials in this message are private and may contain Protected Healthcare Information or other information of a sensitive nature. If you are not the intended recipient, be advised that any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this email in error, please immediately notify the sender via telephone or return mail. _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users