Patent ID: 6844732

Claim:
A Magnetic Resonance imaging apparatus comprising a cavity for accommodating a body under examination or a part thereof, wherein the apparatus is integrated with a device for compensating for unwanted noise fields in said cavity, wherein the device includes: means for determining a strength of a magnetic noise field outside said spatial volume; means for defining on a theoretical basis or on an empirical basis, a correlation between the magnetic noise field outside the spatial volume and a corresponding noise field inside said spatial volume, or calculating the noise field inside the spatial volume, from the measurements of the magnetic noise field outside the spatial volume; from the inside magnetic field, as determined theoretically or empirically, means for generating a magnetic compensation field for neutralizing the noise field in said spatial volume; means for separately detecting magnetic noise fields outside the spatial volume with frequencies in the range of at least two or more different frequency bands; and means for generating one or more corresponding compensation fields for each, or at least some of the noise fields inside the spatial volumes with frequencies in the range of said at least two or more predetermined frequency bands.