SOURCES OF INTENSITY NONUNIFORMITY IN SPIN-ECHO IMAGES AT 1.5-T

This manuscript describes a number of sources of nonuniformity for spin echo images at 1.5 T. Both coil tuning and crosstalk can have significant effects on image nonuniformity. For short repetition times, nonuniformity increases with decreasing TR, possibly due to gradient eddy currents. In sections of RF coils with poor RF uniformity, image nonuniformity varies with both echo time and the number of echoes in a multiecho sequence. For the particular imager used, there are small differences between transverse and sagittal/coronal nonuniformity. The temporal stability of image nonuniformity is very good. The use of uniform oil phantoms is shown to be superior to low pass filtered images for correction of image nonuniformity.