Abstract: Procedures for designing magnets, including superconducting magnets, shim magnets, and gradient magnets for magnetic resonance systems, are provided. The procedures involve the use of a simulated annealing procedure in which weighted spherical harmonics are included in the procedure's error function. The procedure has resulted in the development of previously unknown magnet designs. In particular, superconducting magnets have been designed which include at least one coil in which the current flow is opposite to that in adjoining coils. Such reversed flow in combination with a relatively large number of coils, e.g., more than 6 coils, have enabled the development of short, yet homogeneous, whole body magnets for use in magnetic resonance imaging (MRI).

Abstract: The invention concerns a birdcage resonator used as a transmitter and/or receiver coil in an NMR apparatus. The resonator comprises two ring-shaped conductors each of which is interrupted along its outer periphery by capacitors, the ring-shaped conductors being connected together by axial conducting strips. A plurality of axial conducting strips have their ends located between each pair of peripherally neighbouring capacitors. It is preferred when RF energy is coupled in or out between two conducting strips and when the ring-shaped conductors are shielded by shielding rings in the direction towards the sample. The birdcage resonator in accordance with the invention exhibits an improved RF field homogeneity at higher Q compared to conventional birdcage resonators.

Abstract: Temporal B.sub.o shifts in NMR spectroscopy and/or imaging systems arising from pulsed field gradient induced eddy currents result in the distortion of free induction decay signals. A method of compensation of this distortion through modulation of the sender and/or receiver signal in opposite concert with the induced B.sub.o shifts is introduced. The method has the advantage of having a fast response and of not altering the magnetic gradient field. (FIG.