Hello MRS community,
I am new to MRS and have the bad data to prove it!
- 9.4T Varian/ Agilent magnet
- 100 G/cm SGRAD 88/55/HD/S gradient
- 40mm Millipede quadrature volume RF coil (single channel proton)
- VnmrJ 4.2a software
- PRESS pulse sequence
Currently I am having difficulty shimming an in vivo subject (mouse model). My linewidths on a 3x3x3 mm^3 voxel are 30-60Hz, which is clearly not acceptable based on the consensus publications. I can see “peaks” at around 2.0 and 3.0 ppm but nothing like the results in a typical journal article. For shimming I use the GE3DSHIM for 1&z2 voxel shimming. Other issues are FASTMAP fails to run on my current system and I cannot shim using shimming protocols at 1&2 or higher order. At higher orders the XY and YZ shims max out and are not saved. Do you have any suggestions for breaking past this 30Hz barrier and achieving the recommended linewidths?
More questions to come, but I figured I would start with the most critical problem first. Thanks in advance.