An image registration system, comprising: an endoscope operable for generating an intra-operative endoscopic image of a vessel tree within an anatomical region; and an endoscope controller operable for image registration of the intra-operative endoscopic image of the vessel tree to a pre-operative three-dimensional image of the vessel tree, wherein the image registration includes an image matching of a graphical representation of each furcation of the vessel tree within the intra-operative endoscopic image of the vessel tree to a graphical representation of each furcation of the vessel tree within the pre-operative three-dimensional image of the vessel tree characterized in that the image matching includes: generating a main graph derived from a geometrical representation of the pre-operative three-dimensional image of the vessel tree, the main graph including a main set of connected nodes representative of each furcation of the vessel tree within the pre-operative three-dimensional image of the vessel tree; and generating a subgraph derived from a geometrical representation of the intra-operative endoscopic image of the vessel tree, the subgraph including a subset of the main set of connected nodes and being representative of each furcation of the vessel tree within the intra-operative endoscopic image of the vessel tree; and node matching the subgraph to the main graph. an endoscope operable for generating an intra-operative endoscopic image of a vessel tree within an anatomical region; and an endoscope controller operable for image registration of the intra-operative endoscopic image of the vessel tree to a pre-operative three-dimensional image of the vessel tree, wherein the image registration includes an image matching of a graphical representation of each furcation of the vessel tree within the intra-operative endoscopic image of the vessel tree to a graphical representation of each furcation of the vessel tree within the pre-operative three-dimensional image of the vessel tree characterized in that the image matching includes: generating a main graph derived from a geometrical representation of the pre-operative three-dimensional image of the vessel tree, the main graph including a main set of connected nodes representative of each furcation of the vessel tree within the pre-operative three-dimensional image of the vessel tree; and generating a subgraph derived from a geometrical representation of the intra-operative endoscopic image of the vessel tree, the subgraph including a subset of the main set of connected nodes and being representative of each furcation of the vessel tree within the intra-operative endoscopic image of the vessel tree; and node matching the subgraph to the main graph. generating a main graph derived from a geometrical representation of the pre-operative three-dimensional image of the vessel tree, the main graph including a main set of connected nodes representative of each furcation of the vessel tree within the pre-operative three-dimensional image of the vessel tree; and generating a subgraph derived from a geometrical representation of the intra-operative endoscopic image of the vessel tree, the subgraph including a subset of the main set of connected nodes and being representative of each furcation of the vessel tree within the intra-operative endoscopic image of the vessel tree; and node matching the subgraph to the main graph.