Hongen Liao, Takashi Inomata, Ichiro Sakuma and Takeyoshi Dohi Presented by Zhenzhou Shao

1. 3D Augmented Reality for MRI-Guided Surgery Using Integral VideographyAutostereoscopic Image Overlay Hongen Liao, Takashi Inomata, Ichiro Sakuma and Takeyoshi Dohi Presented by Zhenzhou Shao 2/24/2011

2. Outline • Introduction • Material and Methods • System Configuration • IV Image Display and Overlay Device • Registration of Spatial 3D Image in Patient • Software Alignment • Surgical Procedure • Experiment and Results • Conclusion

3. Introduction • Magnetic resonance imaging (MRI) • A medical imaging technique • Provides detailed information about soft tissue.

4. Introduction • Potential efficacy using MRI-guided surgery • Advantages • Enhance the surgeon’s capability • Decrease the invasiveness of surgical procedure • Increase the accuracy and safety • Disadvantages • Display of a set of 2D sectional images • Hand–eye coordination problem

5. Introduction • Augmented Reality (AR) • Superimpose the virtual model into the real scene. • Video see-through AR • Head mounted display (HMD) • Limited field of view • A lag for motion parallax • Cannot provide a natural view for multiple observers

6. Introduction • Optical see-through AR • Using a semi-transparent mirror for merging virtual model with a direct view. • Surgeon can see through the body. • Enhance the surgeon’s ability to perform a complex procedure. • Depth information is required.

7. Introduction • Integral Videography(IV)

8. System Configuration

9. IV Image and Overlay Device

10. Registration of 3D Image in Patient

11. Registration of 3D Image in Patient

12. Registration of 3D Image in Patient

13. Registration of 3D Image in Patient

14. Software Alignment

15. Surgical Procedure • Calibrate the position of reflected IV image; • Place sterile fiducial markers on the surface of the patient’s body and scan the target area; • Segment the target of interest and markers from the MRI data. Perform patient-to-image registration to find the ;

16. Surgical Procedure • Render the IV images and transfer them to the overlay device; • Perform the surgical treatment under the guidance of IV image overlay; • After finishing the treatment, translate the patient into the scanner again and confirm surgical result.

17. Experiment and Results • Accuracy measurement • Implemented by using markers in a phantom simulating the human head.

18. Accuracy measurement • Five markers for registration and two for error measurement. • Marker: 10 mm in external diameter and 3 mm in internal diameter. • The distance between the center of the actual marker and that of the spatial projected IV marker was measured as an overlay error. • The mean value of the error was 0.90 mm, and the standard deviation was 0.21 mm

19. Targeting Experiment • Compare the procedure time and success rate of targeting an object using 2-D image guidance and IV overlay system guidance. • Phantom consisted of a plastic cube container filled with an agar.

20. Targeting Experiment • Six MRI markers were attached. • Three sets of acrylic cylinders with diameters of 1.5, 2 and 3 mm were embedded within the phantom.

21. 2-D image guidance

22. IV overlay system guidance

23. Results of guidance 2-D image guidance IV overlay system guidance

24. Comparison of procedure time

25. Feasibility Evaluation • Evaluate the feasibility by a volunteer test. • Scan brain using MRI. • Motion parallax could be generated due to the motion of an observer. • The motion parallax of IV autostereoscopic brain images combined with the volunteer’s head was taken from various directions.

26. Feasibility Evaluation

27. In Vivo Animal Experiment • Target a pig’s gallbladder. • A set of markers was attached to the skin of the surgical area.

28. In Vivo Animal Experiment • Surgical planning to minimizing the surgical exposure. • Surgical instrument is tracked. • The targeting experiment was performed by a medical doctor.

29. Conclusion • An autostereoscopic image overlay system for MRI-guided surgery is developed. • IV is employed to provide accurate 3-D spatial images and reproduces motion. • A fast and accurate spatial image registration method was developed. • Safe, easy, and accurate surgical diagnosis and therapy.

30. Questions?