Tracking radiopaque markers using lower rank approximation

In measuring heart motion and deformation radiopaque markers are allowed in a sequence of cine or video frames. Generally, no more than approximately 20 markers can be followed simultaneously because of interruptions of tracks due to missing marker images and ambiguities in the identification of marker images due to closely approaching or crossing of marker tracks. In the present study the authors developed the lower rank tracking (LRT) method which can automatically and reliably follow considerably more than 20 markers in a sequence of video frames. The method was evaluated in computer simulations of markers attached to a moving heart. Using 75 markers in 60 frames 90% was correctly followed, 10% was incompletely followed, and 0.3% were falsely tracked.<>