Hi Michael Thanks for that information, very helpful.
I forgot to mention that we haven't requested the HCP sequences at this point since we have the Siemens MB sequences installed (we may end up requesting them at some point). In any case this first test protocol I created was using the stock non-MB Siemens sequence. Sounds like until we request the HCP sequence, I will use the Siemens strong fat suppression, and I'll have to check what the Siemens MB diffusion sequence offers for fat suppression (presumably it does not have your "grad rev fat supp" option). best mark On Thu, Jul 9, 2015 at 2:30 PM, Harms, Michael <mha...@wustl.edu> wrote: > > 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
