An Interactive Virtual Endoscopy ToolWith 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 2nd 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 RodtSoenke 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
0 0 0 1
x x x x
y y y y
z z z z
VPN VP VU p
VPN VP VU p
VPN VP VU p
T is transformation matrix (translation or rotation along local axis)
VC =
To uniquely determine the coordinates of the virtual camera:
• coordinates of camera: VCnew = VCold * T
• coordinates of the focal point:
FPnew = VCnew * T
Cross Reference
Provided by Arjan Welmers
3D Visualization
Synchronized Virtual Endoscopy