An Interactive Virtual Endoscopy Tool With Automated Path Generation Delphine Nain, MIT AI Laboratory. Thesis Advisor : W. Eric. L Grimson, MIT AI Laboratory.

Presentation Overview Background and Motivation Interactive System Central Path Planning Algorithm Synchronized Virtual Endoscopy Conclusion

Medical Motivation Cancer is the 2 nd cause of death in the US 43 % of people have a risk to be diagnosed with cancer –Out of those 88 % are cancer in inner organ How can “see” inside the body to screen and cure?

Conventional Endoscopy advantages: –minimally invasive –high resolution –interactivity disadvantages: –can be painful and uncomfortable –limited exploration

Conventional Medical Imaging

Conventional Visualization advantages: –non invasive –information on tissue shape through and beyond walls of organ disadvantages: –mentally align contiguous slides –lower resolution than video

Segmentation: Volume

3D Reconstruction : Model

3D Visualization

Virtual Endoscopy Combines strengths of previous alternatives on patient-specific dataset –Spatial exploration –Cross-correlation with original volume Compact and Intuitive way to explore huge amount of information

Virtual Endoscopy: advantages clinical studies: –planning and post-operation: generates views that are not observable in actual endoscopic examinations –color coding algorithms give supplemental information

Virtual Colonoscopy

System Requirements Combination of Interactivity and Automation is key Cross Reference between 3D models and grayscale volumes

Presentation Overview Background and Motivation Interactive System Central Path Planning Algorithm Synchronized Virtual Endoscopy Conclusion

Display

Navigation Interface

Cross Reference Provided by Arjan Welmers

Path: Update

Applications: Middle Ear Thomas Rodt Soenke Bartling

Applications: Cardiovascular Provided by Bonglin Chung

Presentation Overview Background and Motivation Interactive System Central Path Planning Algorithm Synchronized Virtual Endoscopy Conclusion

Automated Path Planning Goal: provide a “create path” button that produces a centerline inside a 3D model of any topology

Input

Output

Step 1: Produce a Labelmap

Step 2: Produce a distance map

Step 3: Create a Graph Create a Graph description of the Distance Map Nodes are voxels inside the model Edge weight are 1/(distance) 2 from the wall of the organ

Step 4: Run modified Dijkstra Dijkstra algorithm is a single source shortest path algorithm We use a binary heap An optimization: keep an evolving front, stop when reach the end node

Step 5: Results Running Time: ~7s

Step 5: Results Running Time: ~3s

Presentation Overview Background and Motivation Interactive System Central Path Planning Algorithm Synchronized Virtual Endoscopy Conclusion

Synchronized Virtual Colonoscopy

Dynamic Programming

Results

Conclusion Combination of Automation and Interactivity is key Cross Reference is important Synchronized Fly-Throughs is novel contribution Publication: D. Nain, S. Haker, E. Grimson, R. Kikinis “An Interactive Virtual Endoscopy Tool”, IMIVA workshop, MICCAI 2001.

Acknowledgements Ron Kikinis Steve Haker Lauren O’Donnell David Gering Carl-Fredrik Westin Peter Everett Sandy Wells Eric Cosman Polina Golland Soenke Bartling John Fisher Mike Halle Ferenc Jolesz

Thank You! Steve Haker, Hoon Ji, Connie Sehnert

Correspondance T is transformation matrix (translation or rotation along local axis) VC = To uniquely determine the coordinates of the virtual camera: coordinates of camera : VC new = VC old * T coordinates of the focal point: FP new = VC new * T

Cross Reference Provided by Arjan Welmers

3D Visualization

Synchronized Virtual Endoscopy