Centrally ordered phase encoding

Abstract

A portion of a subject (22) which is undergoing respiratory or other motion is disposed in an image region (20) to be examined. A respiratory or other motion monitor (50) monitors the cyclic respiratory motion and provides output signals indicative of chest expansion. A phase encoding gradient selector (60) selects the phase encoding gradient that is to be applied by a gradient magnetic field controller (40) and coil (42). A central phase encoding gradient is selected corresponding to a chest relaxation extreme and minimum and maximum phase encoding gradients are selected corresponding to a chest expansion extreme (FIG. 2). Intermediate degrees of monitored physical movement cause the selection of corresponding intermediate phase encoding gradients. Resonance signals collected during each phase encoding gradient are Fourier or otherwise transformed (80) into a corresponding view. A filter (92) weights each view such that views closest to the central phase encoding gradient are weighted most heavily and views adjacent the minimum and maximum phase encoding gradients are weighted least heavily. The physical position of pixels within each view are scaled (94) to adjust each view in accordance with the degree of physical expansion. The weighted and scaled views are transformed into an image memory (120) for display on a video display (122) or the like.