Hi Matt, 32 channel head coil.
I was able to run the diffusion sequence on a phantom when TR/TE was 7000/106 ms. Since the scan time with this tr is already 20 minutes, I was thinking to acquire just b0 with PA phase encoding and the other 64 directions 2b data+b0 with AP. will that be okay? my concern is snr at te will not be very good and data may not be too great and may be atleast 2 reps are desired? Thanks Regards -VM On Dec 6, 2016 6:46 PM, "Glasser, Matthew" <glass...@wustl.edu> wrote: > What coil are you using? > > Peace, > > Matt. > > From: <hcp-users-boun...@humanconnectome.org> on behalf of neuroimage > analyst <neuroimage.anal...@gmail.com> > Date: Tuesday, December 6, 2016 at 11:56 AM > To: "hcp-users@humanconnectome.org" <hcp-users@humanconnectome.org> > Subject: [HCP-Users] Skyra - BOLD and diffusion MRI protocols > > Hi, HCP Users and Developers. > > We have been trying to build a protocol for BOLD and DWI on our Skyra > (VE11C) using the latest release of HCP pulse sequences. But we > haven't been completely successful with what we wanted to achieve. > > A) BOLD: We were hoping to get a TR in the range of 750ms, res = 2mm3, > echo spacing (ES) approx 0.65. We were able to get to echo spacing of 0.69 > and all the other parameters with MB = 8. However, the sequence doesn't run > and it gives us "Max amplitude overflow on gradient z axis" after MB factor > exceeds 2. It appears to me that then we have to sacrifice TR and only run > with MB = 2. Is there anybody with a Skyra who has able to achieve what we > are hoping for and willing to share the protocol with us? OR if somebody > could guide us to resolve the error of amplitude overflow. > > B) DWI: The idea was to have res = 1.5mm3, 2b-values at 1000 and 2500, 64 > directions with the best BW and ES achievable. The sequence runs for 7 > minutes out of total 13 minutes and gives gradient power amplifier error. > On Michael Harms's suggestion, I adjusted flip angle to 78/160 at a TR of > 5500 ms with excite/refocus pulse duration of 3840 and 7680. there was a > pop up warning that RF is clipped and the maximum refocusing angle was 142 > instead of 160. I placed a 64 directions diffusion vector and ran the > sequence under "free" mode. Again, I will appreciate if there is anybody > with a Skyra who has able to achieve what we are hoping for and willing to > share the protocol with us, along with the diffusion vector sets? OR if > somebody could guide us to resolve the error. > > Thank you. > > Regards > > --VM > > _______________________________________________ > 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
