Improved reduction of motion artifacts in diffusion imaging using navigator echoes and velocity compensation

Navigator echoes provide a means with which to remove motion artifacts from diffusion-weighted images obtained using any multishot imaging technique. However, residual motion artifact is often present in the corrected images rendering the technique unreliable. It is shown that velocity-compensated d iffusion sensitization when used in tandem with a navigator echo further re duces the degree of residual motion artifacts present in the corrected imag es and improves the reliability and clinical utility of the technique. This is demonstrated by applying a method for quantification of motion artifact to brain images of healthy volunteers scanned using both conventional (Ste jskal-Tanner) and velocity-compensated gradient sensitization. Other factor s affecting the efficacy of the navigator echo technique, such as brain pul satile motion, gradient b factor, and navigator echo signal-to-noise ratio, are also discussed. (C) 2000 Academic Press.