Vertical field type MRI apparatus with a conical cavity situated in the main magnet

A vertical field type MRI apparatus for forming magnetic resonance images, including;

• at least one first field generating superconducting coil system for producing a substantially homogeneous magnetic field in an imaging volume of the apparatus, which coil system includes:
• a round outer coil arranged in an outer coil plane;
• and
• a round supplementary coil arranged within the outer coil, wherein the energizing of the outer coil and of the supplementary coil generates magnetic fields of opposite direction, wherein the supplementary coil is located in the outer coil plane, and wherein the ratio Da/Do of the diameter Da of the supplementary coil to the diameter Do of the outer coil is between 0.7 and 0.9;
• and
• a second field generating superconducting coil system for producing the substantially homogeneous magnetic field in the imaging volume of the apparatus, which second coil system includes:
• a second round outer coil arranged in a second outer coil plane and having a diameter that is larger than the diameter of the first outer coil,
• a second round supplementary coil arranged within the second outer coil and in the second outer coil plane wherein the energizing of the second outer coil and of the second supplementary coil generates magnetic fields of opposite direction, and further including a first and a second container for the first and the second field generating superconducting coil systems, respectively, said containers being arranged to contain a cryogenic medium and communicating with one another in order to exchange the cryogenic medium, one of the containers being provided with a pressure connection for controlling the pressure in the containers as desired.