1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States
A correction method is presented that removes spatial artifacts related to magnetic field drift in MRI systems equipped with ferro-shim elements usually placed close to high power gradient systems. At high duty cycle of gradients the heat generated inside the magnet bore reduces the effectiveness of shim elements by shifting the temperature closer to the Curie point. In response to unequal initial radial distribution of these elements the new magnetic field is no more uniform than it was at room temperature. Higher order corrections are required to remove artifacts from the time-series of phase images.