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 at the second time from the scan data; 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 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.