BrainWeb.field_ppm

property BrainWeb.field_ppm

The field the head adds to B0 at each voxel, (z, y, x), in ppm of B0, as a first-order shim leaves it.

The head is water, and the background air, each voxel in proportion to the fraction of it the background fills. The field along B0, the physical z axis, is the susceptibility convolved with the dipole kernel, the Lorentz sphere’s third included (Marques and Bowtell, Concepts Magn Reson B 25:65, 2005), whose constant and linear terms over the voxels at least half head are then removed.