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

3D Augmented Reality for MRI-Guided Surgery Using Integral Videography

Autostereoscopic Image OverlayHongen Liao, Takashi Inomata, Ichiro

Sakuma and Takeyoshi Dohi

Presented by Zhenzhou Shao2/24/2011

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

Introduction

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

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

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

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.

Introduction

• Integral Videography(IV)

System Configuration

IV Image and Overlay Device

Registration of 3D Image in Patient

Registration of 3D Image in Patient

Registration of 3D Image in Patient

Registration of 3D Image in Patient

Software Alignment

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 ;

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.

Experiment and Results

• Accuracy measurement– Implemented by using markers in a phantom

simulating the human head.

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

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.

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.

2-D image guidance

IV overlay system guidance

Results of guidance

2-D image guidance

IV overlay system guidance

Comparison of procedure time

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.

Feasibility Evaluation

In Vivo Animal Experiment

• Target a pig’s gallbladder.• A set of markers was attached to the skin of

the surgical area.

In Vivo Animal Experiment• Surgical planning to minimizing the surgical

exposure.• Surgical instrument is tracked.• The targeting experiment was performed by a

medical doctor.

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.

• Questions?