Fig. 1.

Magnet setup. a The Halbach magnet, producing an 0.05 T magnetic field at the center. b The $B_0$ field was measured on a 225 × 225 × 300 mm³ with a gaussmeter connected to a robot. After subtraction of the center frequency and conversion to Hz it was fitted to a basis of second-order spherical harmonics. The field in the center transversal slice of the magnet shows inhomogeneities up to approximately ± 1200 Hz. The dashed lines indicate the position of the inner diameter of the magnet. c Schematic overview of the reconstruction algorithm for iterative CPR and iterative MB. In each iteration, two images are reconstructed from the unshifted and shifted acquisitions. The phase of the resulting images is used to map the $\mathrm{\Delta }{B}_0$ field. The $\mathrm{\Delta }{B}_0$ map is used as input in the CPR and MB reconstruction in the next iteration