Banding artifacts along the frequency-encoding direction in multi-echo magnetic resonance imaging: Origin and a remedy

We report here a highly reproducible artifact seen in standard multi-echo spin-echo imaging, in which severe banding was seen along the frequency-encoding direction for all late echo images, but not for the first echo. A theoretical analysis showed that the banding resulted from the destructive interference effects of the stimulated echo in the presence of both an inaccurate calibration of the RF pulse flip angles and a gradient area offset. Experimental results from a water phantom verified the origin. A remedy method employing crusher gradients with alternating amplitudes was proposed and implemented, which successfully eliminated the artifacts as evidenced by in vivo imaging results from human brain.