Figure 3.

Motion artifacts and motion artifact reduction obtained through the combination of numerical motion tracking and dual channel excitation ratiometry using blue and green excitation light. (A) Optical maps showing mostly motion artifacts before tracking in uncompensated videos in blue and green channels, respectively. (B) Optical maps after motion tracking and stabilization. Dissociation-related motion artifacts are compensated and substantially reduced. The blue channel contains no electrophysiology-related signal, and the optical maps exhibit merely residual intensity modulations caused by relative motion between tissue and light sources, which persists after tracking (see also Figure 1C). The green channel exhibits an action potential wave propagating across the ventricular surface (dark: depolarized tissue). (C) Both dissociation- and illumination-related motion artifacts are compensated due to the combined, subsequent use of tracking and ratiometry. The optical maps show an essentially artifact-free action potential wave propagating across the deforming heart surface (dark: depolarized tissue). In all optical maps, the optical signal was normalized in each pixel over time (normalized units [n.u.], pixel-wise normalization) as the last processing step after numerical motion correction and ratiometry.