Non-invasive Placement and 3D Tracking of Myocardial Beads with SPAMM-tagged Magnetic Resonance Imaging

In this paper, a specific Spatial Modulation of Magne t i za t ion (SPAMM) imaging protocol and associated image analysis methods are proposed. T h e imaging process creates long axis tag p lanes which are coincident with short-axis i m a g e slices a t t h e t i m e of on-set of tags. In addition, o n e se t of short-axis tag planes are created coincident w i t h long-axis image slices a t the t i m e of on-set of tags. O n c e short-axis and long-axis tag data synchronized w i t h o n e another and wi th t h e EKG signal are obtained, t h e three sets of tag p lanes ( two intersecting short-axis image slices and o n e intersecting long-axis i m a g e slices) are continuously reconstructed across several i m a g e slices for all temporal f r a m e s during the heart cycle with B-spline surfaces. Subsequently, a computer algorithm de termines the intersection of these 3 sets of surfaces for a n u m b e r of material po in ts of t h e LV myocardium, allowing for visualization of 3D m o t i o n of these non-invasively placed beads during t h e entire cardiac cycle.