Two‐step navigatorless correction algorithm for radial k‐space MRI acquisitions

A new way to correct magnetic resonance image artifacts resulting from view‐dependent phase variations and view‐dependent variations in rigid body object translation is presented by exploiting basic properties of the trajectory of radial k‐space acquisitions. Simulations, phantom studies, and in vivo experiments are used to demonstrate the feasibility and the utility of this method. While somewhat analogous to navigator echo correction, in which special gradients are interleaved into the imaging sequence so echoes at the center of k‐space can be acquired prior to or after collection of the image data, the current method does not require additional new gradient structures within the pulse sequence or increases in scan time. The new method uses the phase information from all collected radial k‐space data points rather than only the navigator echo, which permits correction of multiple sources of view‐dependent phase variation in the image data. The resultant effect is improved image quality in radial MRI acquisitions. Magn Reson Med 45:277–288, 2001. © 2001 Wiley‐Liss, Inc.