Simulated vascular reconstruction in a virtual operating theatre

1. Simulated vascular reconstructionin a virtual operating theatre Robert G. Belleman, Peter M.A. Sloot Section Computational Science, University of Amsterdam,Kruislaan 403, 1098 SJ Amsterdam, the Netherlands.Email:(robbel|sloot)@science.uva.nl

2. Overview • Interactive distributed simulation • Simulated vascular reconstruction in a virtual environment • Performance issues • High speed simulation • High speed communication • Responsive interactive exploration • Time/location independence

3. Interactive distributed simulation • Human in the loop experimentation • interactive exploration of data/parameter spaces

4. Performance issues • Asynchronous, pipelined configuration • Distributed to exploit specialised resources • To increase performance: • decrease component execution times • shorten delays

5. Vascular reconstruction • “Traditional” treatment

6. Vascular reconstruction (Figure courtesy C.A. Taylor, Stanford University)

7. Simulated vascular reconstruction • Simulated treatment planning

8. Simulated vascular reconstruction • Components: • blood flow simulation • visualization in a virtual environment • interaction with simulation and visualization (treatment planning) • Requirements: • Interactive system; fast response, fast update rate

9. Fluid flow simulation • Lattice Boltzmann Method (LBM) • Lattice based particle method • Regular lattice, similar to CT or MRI datasets • Allows irregular 3D geometry • Allows changes at run-time • Velocity, pressure and shearstress calculated fromparticle densities • Non-compressiblehomogeneous fluid,laminar flow • Spatial and temporal locality • Ideal for parallelimplementation

10. Preprocessing • Segmentation of patient specific MRA/CTA scan • Isolates region of interest • Lattice Boltzmann grid generation • Defines solid and fluid nodes, inlet and outlet conditions

11. Interactive exploration in VR • Visualize simulation results • Flow field, pressure, shear stress • Real time • Interactive exploration • VR interaction to locateregions of interest • Interactive grid editing • Simulate vascularreconstruction procedure

12. Interactive exploration in VR • Visualize simulation results • Flow field, pressure, shear stress • Real time • Interactive exploration • VR interaction to locateregions of interest • Interactive grid editing • Simulate vascularreconstruction procedure

13. Parallel fluid flow simulation • Performance indication:

14. Communication delay • 10-100Mb of data per iteration • Velocity, pressure, shear stress • May take seconds to transfer • Increasing communication throughput • Latency hiding • Decrease latency: faster response time, increased update rate • Payload reduction • Less data: shorter transfer times

15. Latency hiding • Multiple connections • Waiting for acknowledgements is hidden • Packets can travel through different routes • Uses CAVERN

16. Payload reduction • Data encoding • Decreases level of detail • Accuracy determined by type of representation • Lossy compression • Induces latency • “Standard” compression libraries (zlib) • Reduction to 10% not uncommon • Lossless compression • Induces latency

17. Communication pipeline • Cascade of encoding, compression and multiple socket connections

18. Pipeline performance Latency hiding: Payload reduction:

19. The Virtual Laboratory • Shared use of distributed computing resources:high performance computers, scanners, algorithms, etc. • Connected via high performance networks • Common infrastructure: the Virtual Laboratory • Multi-disciplinary scientific experimentation • Problem solving environments (PSE) • Time/location independent scientific experimentation • Collaborative scientific research For additional information... DutchGrid initiative : http://www.dutchgrid.nl/ VLAM-G : http://www.dutchgrid.nl/VLAM-G/

20. Experiment definition • Simulated vascular reconstruction • Patient specific angiographydata • Fluid flow simulationsoftware • Simulation of reconstructivesurgical procedure in VR • Interactive visualization ofsimulation results in VR • Pre-operative planning • Explore multiple reconstructionprocedures

21. Where are we going? • Improve blood flow simulation • High performance visualization and rendering • Time/location(/device?) independent interactive simulation • Access to high performancecomputing resources overlow bandwidth connections • Use anywhere, at any time…onanything?

22. Where are we going? • Improve blood flow simulation • High performance visualization and rendering • Time/location(/device?) independent interactive simulation • Access to high performancecomputing resources overlow bandwidth connections • Use anywhere, at any time…onanything?

23. Where are we going? • Improve blood flow simulation • High performance visualization and rendering • Time/location(/device?) independent interactive simulation • Access to high performancecomputing resources overlow bandwidth connections • Use anywhere, at any time…onanything?

24. Where are we going? • Improve blood flow simulation • High performance visualization and rendering • Time/location(/device?) independent interactive simulation • Access to high performancecomputing resources overlow bandwidth connections • Use anywhere, at any time…onanything?

25. Thanks! • UvA, Section Computational Science • Sloot, Hoekstra, Zhao, Artoli, Merks, Shulakov, Shamonin • Leiden University Medical Center (LUMC) • LKEB (Reiber, vd Geest, Koning, Schaap) • Stanford University • Biomedical department (Zarins, Taylor) • SARA Computing and Networking Services Related work: • Lattice Boltzmann flow simulation: Artoli, Hoekstra (UvA/SCS) • Segmentation of MRA images: Koning, Schaap (LUMC) • Agent based solutions to interactive systems: Zhao (UvA/SCS)