Cardiac and respiratory motion compensated reconstruction driven only by 1D navigators

INTRODUCTION Cardiac MRI requires compensation of respiratory and cardiac motion, which is usually performed by gating using an ECG and breathing signal. Recently, a motion compensated reconstruction of arbitrary physiological motion was proposed [1], that is based on a generalized reconstruction by inversion of coupled systems (GRICS) and uses a motion model and a reduced number of 1D input signals for driving this model. External motion sensors (e.g. respiratory bellows) were used to drive the model. Recently self-gated methods were also proposed by extracting respiratory [2] and ECG signal [3] from additionally acquired central k-space profiles. However, such navigator data are usually used for gating or slice tracking, assuming rigid body motion along the navigator profile (motion is described by a scalar value). This work focuses on the analysis of such 1D navigators, in the context of a multiple coil acquisition (providing localized information). Motion eigenmodes are determined from 1D navigators of a 32-channel coil array, which are then used as inputs for the GRICS motion compensated reconstruction. The approach was tested in cardiac function studies of healthy volunteers under free breathing and without using an external ECG-signal.