Siemens "strong fat suppression” = fat sat pulse + gradient reversal
> On Jul 9, 2015, at 2:37 PM, Mark A. Pinsk <mpi...@gmail.com> wrote: > > 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 > _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users
