Field compensation system for magnetic resonance scanner - uses auxiliary field coils to correct asymmetry effects

摘要

The magnetic resonance scanner has a measurement area (28) inside a metal cylindrical shield (3). So called 'Bo magnet' coils (2) produce a stationary magnetic while an inner r.f. coil (10) produces the varying field. Phase changes in the r.f. current are detected (16) and the phase change data is fed to a computer (18) and used to control (24, 20. 12) the r.f. coil current. The computer generates the data for the display image (22). The novel feature of the present scanner is that additional auxiliary coils (32) are fed from a supply (34) to correct any field asymmetry. @(7pp Dwg.No.1/1)@.