Non-invasive placement and 3D tracking of myocardial beads with SPAMM-tagged magnetic resonance imaging

In this paper, a specific Spatial Modulation of Magnetization (SPAMM) imaging protocol and associated image analysis methods are proposed. The imaging process creates long axis tag planes which are coincident with short-axis image slices at the time of on-set of tags. In addition, one set of short-axis tag planes are created coincident with long-axis image slices at the time of on-set of tags. Once short-axis and long-axis tag data synchronized with one another and with the EKG signal are obtained, the three sets of tag planes (two intersecting short-axis image slices and one intersecting long-axis image slices) are continuously reconstructed across several image slices for all temporal frames during the heart cycle with B-spline surfaces. Subsequently, a computer algorithm determines the intersection of these 3 sets of surfaces for a number of material points of the LV myocardium, allowing for visualization of 3D motion of these non-invasively placed beads during the entire cardiac cycle.