Method for measuring three-dimensional motion with tagged MR imaging

Recent methods of magnetic resonance imaging involve the placement of a grid of planes of saturation over the imaging plane; distortion of the grid corresponds to tissue displacement in two dimensions. An extension to this method that allows measurement of motion in the third dimension involves a second acquisition that tilts the grid, allowing analysis of motion normal to the imaging plane. A rotating phantom was used to verify the accuracy of the motion measurements, and the technique was applied to the heart wall and skeletal muscle. Phantom results show that the measure of z motion can be as accurate as that of x and y motion. Three-dimensional displacements of heart-wall and skeletal muscle are shown. With an accurate measure of three-dimensional motion, more complete analysis of heart-wall motion and contraction is possible.