1. An apparatus for determining tracking a motion of at least one portion of an anatomical structure, comprising: at least one detector first arrangement which is configured to simultaneously detect a plurality of electromagnetic radiations which are provided from multiple points within the at least one portion, wherein the electromagnetic radiations are received in a confocal configuration; and at least one computer second arrangement which is configured to (i) obtain at least one reference first image of the at least one portion, and (ii) generate at least one sparsely-sampled second image of the at least one portion based on the detected electromagnetic radiations, wherein the second arrangement is further configured to determine the motion based on a comparison of the first and second images.