Generating 3-D cardiac material markers using tagged MRI

Abstract

Tagged magnetic resonance imaging (MRI) has shown great promise in noninvasive analysis of heart motion. To replace implanted markers as a gold standard, however, tagged MRI must be able to track a sparse set of material points, so-called material markers, with high accuracy. This paper presents a new method for generating accurate motion estimates over a sparse set of material points using standard, parallel-tagged MR images. The tracked points are located at intersections of three tag surfaces, each of which is estimated using thin-plate splines. The intersections are determined by an iterative alternating projections algorithm for which a proof of convergence is provided. The resulting data sets are compatible with applications developed to exploit implanted marker data. One example from a normal human volunteer is shown in detail, and numerical results that include additional studies are discussed.