Patent ID: RE39460

Claim:
A magnetic resonance system for producing MR images comprising an asymmetric superconducting magnet which produces a magnetic field which is substantially homogeneous over a predetermined region (the “dsv”) whose diameter is greater than or equal to 40 centimeters, said magnet having a longitudinal axis and comprising a plurality of current carrying coils which surround the axis, are distributed along the axis, and define a turn distribution function T(z) which varies with distance z along the axis and is equal to the sum of the number of turns in all coils at longitudinal position z, wherein: (i) the longitudinal extent of the plurality of coils defines first and second ends for the superconducting magnet, (ii) the variation of the longitudinal component of the magnetic field calculated to be produced in the dsv by the plurality of coils is less than 20 parts per million peak-to-peak, (iii) the dsv defines a midpoint M which is closer to the first end than to the second end, (iv) the midpoint M of the dsv is spaced from the first end by a distance D which is less than or equal to 40 centimeters, and (v) the turn distribution function T(z) has a maximum value which occurs at a longitudinal location that is closer to the first end than to the second end.