Motion compensation of optical mapping signals from rat heart slices

Optical mapping is a well established technique for recording monophasic action potential traces either within myocardial slices or on the epicardial surface of isolated hearts. This measuring technique offers a high spatial and sufficient temporal resolution but it is sensitive towards myocardial motion. Motion artifacts occur because the mapping between a certain tissue portion sending out fluorescent light and a pixel of the photodetector changes over time. So far this problem has been adressed in two different ways: Suppressing the motion or ratiometric imaging. Working with beating rat heart slices we developed a different approach to noninvasively record simultaneously optical mapping data and motion of the slices. Our approach is based on image registration. We use the background fluorescent light to perform first a rigid transformation to detect translational and and rotational motion. The contractive motion is recovered using a non-rigid demons registration algorithm afterwards. The investigation is based on recordings of four different slices stained with Di-4-ANEPPS.