Tracking rolling leukocytes with motion gradient vector flow

Recording rolling leukocyte velocities from intravital microscopic video imagery is important to inflammation research and drug validation. Since manual tracking is excessively time consuming, an automated method is desired. This paper illustrates an active contour based automated tracking method, where we propose a novel external force to guide the active contour by taking the flow direction into account. The construction of the proposed force field, referred to as motion gradient vector flow (MGVF), is accomplished by minimizing an energy functional involving the motion direction, and the image gradient magnitude. The tracking experiments demonstrate that MGVF can be used to track both slow and fast leukocytes, whereas the basic gradient vector flow (GVF) is suitable for tracking slow leukocytes.