Abstract: A magnetic resonance imaging scanner includes a main magnet (20) generating a main B0 magnetic field, one or more shim coils (60) selectively shimming the main B0 magnetic field at selected shim currents, and a processor (70) executing a process including determining a magnitude shift of the main B0 magnetic field responsive to the selective shimming and performing a correction during the energizing to correct for the determined magnitude shift of the main B0 magnetic field. The performed correction includes one of (i) selectively energizing a D.C. shim coil (82) to counteract the determined magnitude shift of the main B0 magnetic field and (ii) computing a magnetic resonance frequency corresponding to the main B0 magnetic field including the determined magnitude shift and tuning a radio frequency transceiver (44, 46) to the computed magnetic resonance frequency.

Abstract: A magnetic resonance imaging scanner (10) performs magnetic resonance imaging. The scanner (10) includes a main magnet (20) generating a main magnetic field, magnetic field gradient coils (30), and at least one radio frequency antenna (32, 34). At least one magnetic field sensor (32, 34, 64, 66, 68, 70, 72) measures spatial data corresponding to the main magnetic field. A processor (60) processes the measured spatial data corresponding to the main magnetic field to determine at least one main magnetic field nonuniformity parameter. The at least one magnetic field sensor (32, 34, 64, 66, 68, 70, 72) and the processor (60) operate concurrently with the magnetic resonance imaging.

Abstract: In a method for shimming a magnetic resonance imaging scanner (10), at least one of fat suppression and blood suppression is performed to suppress magnetic resonance from a corresponding at least one of fat and blood. First and second magnetic resonance echoes emanating from a generally columnar volume are measured. The measurements of the first and second magnetic resonance echoes (122, 124) are reconstructed (150) into corresponding first and second generally columnar projection images (152, 154). The first and second generally columnar projection images are combined (160) to produce a magnetic field profile (174) of the generally columnar volume. Selected magnetic field parameters are extracted (142) from the magnetic field profile. Shim currents are computed (180) from the selected magnetic field parameters. The shim currents are applied to magnetic field coils (16, 60).