FAMASITO: FASTMAP Shim Tool towards user-friendly single-step B0 homogenization

NMR Biomed. 2021 Jun;34(6):e4486. doi: 10.1002/nbm.4486. Epub 2021 Feb 17.

Abstract

Fast, automatic shimming by mapping along projections (FASTMAP) is an elegant analytical method developed to quantify three-dimensional first- and second-order spherical harmonic B0 shapes along six one-dimensional column projections. The straightforward application of this theoretical concept to B0 shimming, however, neglects crucial aspects of sequence implementation and shim hardware, commonly necessitating multistep iterative adjustments. We demonstrate a software package, referred to as FASTMAP Shim Tool (FAMASITO), which is composed of a FASTMAP pulse sequence, automated calibration and analysis routines, and a script for automatically performing experiments. With FAMASITO we demonstrate optimal single-step adjustment of first- and second-order terms (with potential <1% mean refinement of linear terms) in the prefrontal cortex of seven volunteers, one of the most difficult-to-shim areas in the adult human brain.

Keywords: FASTMAP; active shimming; spherical harmonic functions.

MeSH terms

  • Algorithms*
  • Automation
  • Calibration
  • Humans
  • Magnetic Resonance Imaging*
  • User-Computer Interface