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Comparison of intensity-based B-splines and point-to-pixel tracking techniques for motion reduction in optical mapping experiments

Suppression of motion artifacts (MA) in cardiac optical mapping usually requires uncoupling of cardiac contraction by restriction techniques, which are known to have important effects on cardiac physiology deteriorating the quality of acquisitions and their interpretation. In this study, we propose to assess the performance of two independent intensity-based post-processing strategies to minimize MAs during registration. A point-to-pixel block-matching classical similarity-based tracking with displacement interpolation is compared to a well-known non-rigid registration algorithm where the deformation field is obtained using cubic splines. Both strategies were tested on synthetic and real optical mapping sequences, and further compared based on their tracking accuracy and ability to maintain activation and repolarization information of the reconstructed action potentials in wide areas of the epicardial surface. The algorithms proved to be accurate tracking frame-to-frame axial geometrical displacements. Yet, special care must be taken to preserve upstroke information intact.