Electromagnetic shielding for magnetic resonance imaging methods and apparatus

A portable magnetic resonance imaging system, comprising:

• at least one permanent B0 magnet comprising a plurality of concentric permanent magnet rings, the at least one permanent B0 magnet configured to produce a B0 field for an imaging region of the portable magnetic resonance imaging system;
• electromagnetic shielding for the imaging region of the portable magnetic resonance imaging system, the electromagnetic shielding comprising a first shield member configured to provide a variable amount of shielding of the imaging region of the portable magnetic resonance imaging system;
• and
• an antenna capacitively coupled to a power line of the magnetic resonance imaging system, and configured to use measurements obtained by the antenna to suppress noise in an RF signal received by an RF coil of the magnetic resonance imaging system;
• wherein the at least one permanent B0 magnet comprises a first permanent B0 magnet and a second permanent B0 magnet disposed opposite the first B0 permanent magnet, with the imaging region between the first permanent B0 magnet and the second permanent B0 magnet.

A portable low-field magnetic resonance imaging system, comprising:

• at least one magnet configured to produce a magnetic field, at a strength of less than 0.2 T and greater than 50 mT, for an imaging region of the low-field magnetic resonance imaging system;
• electromagnetic shielding for the imaging region of the portable low-field magnetic resonance imaging system, the electromagnetic shielding comprising a slidable first shield member configured to allow the first shield member to be opened and closed to provide an amount of shielding of the imaging region of the portable low-field magnetic resonance imaging system that is variable between at least a first amount of shielding and a second amount of shielding of the imaging region;
• and
• an antenna capacitively coupled to a power line of the magnetic resonance imaging system, and configured to use measurements obtained by the antenna to suppress noise in an RF signal received by an RF coil of the magnetic resonance imaging system;
• wherein the at least one magnet comprises a first permanent magnet and a second permanent magnet disposed opposite the first permanent magnet, with the imaging region between the first permanent magnet and the second permanent magnet.