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

This manuscript describes a number of sources of nonuniformity for spi n echo images at 1.5 T. Both coil tuning and crosstalk can have signif icant effects on image nonuniformity. For short repetition times, nonu niformity increases with decreasing TR, possibly due to gradient eddy currents. In sections of RF coils with poor RF uniformity, image nonun iformity varies with both echo time and the number of echoes in a mult iecho sequence. For the particular imager used, there are small differ ences between transverse and sagittal/coronal nonuniformity. The tempo ral stability of image nonuniformity is very good. The use of uniform oil phantoms is shown to be superior to low pass filtered images for c orrection of image nonuniformity.