Model tags: Direct 3D tracking of heart wall motion from tagged MR images

Abstract

A method is presented for the reconstruction of 3D heart wall motion directly from tagged magnetic resonance (MR) images, without prior identification of ventricular boundaries or tag stripe locations. Model tags were created as material surfaces which defined the location of the magnetic tags within the model. Image-derived forces acted on the model tags, while the model could also be manipulated by a small number of user-controlled guide points. The method was applied to simulated images in which the true motion was specified, as well as to clinical images of a normal volunteer. The RMS errors in displacement and strain calculated from the simulated images were similar to those obtained using previous stripe tracking and model fitting methods. A significant improvement in analysis time was obtained for the normal volunteer, making the method more clinically viable.