Parametric modeling of the beating heart with respiratory motion extracted from magnetic resonance images

In atrial fibrillation ablation procedures on-line measurement of catheter position is often displayed to the clinician against a static anatomy from pre-procedure scans. However the heart is moving due to both contraction and respiratory motion. Thus both small-scale and large-scale inaccuracies are introduced into the visualization. As part of a larger project to improve delivery of ablation, we are developing parametric models to animate static three-dimensional pre-procedure anatomical models to include the dynamics. To make our heart model “beat” we combine image processing methods with Fourier and polynomial representations, and combine global and local smoothing. The result is an efficient parameterization of the moving surface over both space and time. The steps for making the heart move due to respiration are only partially complete. Here we concentrate on registering a sequence of ungated MR slice sequences. The approach involves parameterizing motion of curves representing anatomical landmarks and enforcing consistency in the cross-slice direction.