Cancellation due to Rigid Motion in the Imaging Plane 1 Reza

A post-processing technique has been developed to suppress the MRI artifact arising from object planar rigid motion. In 2-DFT MRI, rotational and translational motions of the target during MR scan respectively impose non-uniform sampling and a phase error on the collected MRI signal. The artifact correction method introduced considers the following three conditions: (i) For planar rigid motion with known parameters, a reconstruction algorithm based on bilinear interpolation and the super-position method is employed to remove the MRI artifact. (ii) For planar rigid motion with known rotation angle and unknown translational motion (including an unknown rotation center), rst, a super-position bilinear interpolation algorithm is used to eliminate artifact due to rotation about the center of the imaging plane, following which a phase correction algorithm is applied to reduce the remaining phase error of the MRI signal. (iii) To estimate unknown parameters of a rigid motion, a minimum energy method is proposed which utilizes the fact that planar rigid motion increases the measured energy of an ideal MR image outside the boundary of the imaging object; by using this property, all unknown parameters of a typical rigid motion are accurately estimated in the presence of noise. To con rm the feasibility of employing the proposed method in a clinical setting, the technique was used to reduce unknown rigid motion artifact arising from the head movements of two volunteers.