On-shoulder MRI magnet for human brain imaging

A magnetic resonance imaging magnet comprising:

• a) a generally annularly cylindrical-shaped vacuum enclosure having:
• (1) a generally longitudinally extending axis,
• (2) first and second longitudinal ends,
• (3) a first bore generally coaxially aligned with said axis, extending with a generally constant radius from said first longitudinal end towards said second longitudinal end, and spaced apart from said second longitudinal end, and
• (4) a second bore generally coaxially aligned with said axis and extending with a generally constant radius from said second longitudinal end to said first bore, wherein said radius of said second bore is smaller than said radius of said first bore;
• b) a plurality of longitudinally spaced-apart superconductive coils generally coaxially aligned with said axis and disposed within and spaced apart from said vacuum enclosure, said superconductive coils including a first coil and a second coil each carrying an electric current in generally the same direction, said first coil generally circumferentially surrounding said first bore and said second coil generally circumferentially surrounding said second bore, said second coil having a radially innermost portion, and wherein the radial distance of said radially innermost portion of said second coil from said axis is smaller than said radius of said first bore;
• and
• c) a gradient coil disposed within said first bore and having a radially innermost portion, wherein the radial distance of said radially innermost portion of said gradient coil from said axis is generally at least as large as said radius of said second bore.