Magnetic resonance imaging systems and methods

A method for magnetic resonance imaging (MRI) near metal or magnetic objects such as implants comprises: acquiring an image at a first main magnetic field value; acquiring an image at a second main magnetic field value; and combining the images to provide a corrected image with reduced metal distortion. An MR imaging system for performing the method includes a superconducting magnet, a power supply for a current to ramp the magnetic field, a magnetic field controller programmed to ramp the main magnetic field by adjusting the current generated by the power supply, and a data acquisition and processing system to receive the MR signals, generate image data sets and combine them to provide a corrected image having a reduced metal distortion. First and second transmit frequencies may be used in the first and second image acquisitions. Each transmit frequency may have a resonant frequency and an offset frequency.