1. A method for matching deformable, anatomical trees represented by scan data, the method comprising: acquiring, from a medical imaging system, the scan data representing a tree structure of a patient at first and second times; calculating, by a processor, tangents along the tree structure at the first time and tangents along the tree structure at the second time from the scan data acquired at the first and second times, respectively; matching, by the processor, the tree structure at the first time with the tree structure at the second time, the matching being performed with coherent point drift where the tangents of both the first and second times are included as part of a cost function of the coherent point drift; and outputting, by the processor, an image representing the matched tree structure from the first and second times.