Ah ha, many thanks for that information. On Thu, Jul 9, 2015 at 4:44 PM, Xu, Junqian <junqian...@mssm.edu> wrote:
> 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
