1. In an MRI apparatus comprising a non-superconducting electromagnet and a plurality of pole pieces, means for improving the image quality, said means for improving the image quality comprising means for decreasing sensitivity to B 0 field instability; wherein said means for decreasing sensitivity to B 0 field instability comprises: a. means for correcting for drift of the excited volume comprising means for applying broad band RF excitation pulses with strong selection gradients and/or means for providing a real time change in the TX frequency adapted to obtain a smooth change during the scan; and b. means for correcting for drift of the frequency and/or phase of the acquired data, comprising means for collecting navigator echoes as extra FID and means for obtaining a linear phase correction function of each FID from said collected navigator echoes; wherein said means for improving the image quality enables reduction in at least one of the following without reduction in the imaging resolution: (a) distance between item being imaged and at least one of said electromagnets; (b) magnetic field; (c) temperature of said electromagnet.