virtual reality in medicine - department of computer science › ~cohen › vw2000 › lectures ›...
TRANSCRIPT
![Page 1: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/1.jpg)
Virtual Reality in Medicine
16-17 March 2000Johns Hopkins University
Terry S. Yoo, HPCC OfficeNational Library of Medicine, NIH
Data
• Image generation from clinical data.
• Obligation to representing the truth.
• Precision, accuracy, repeatability.
• Where does it come from?
![Page 2: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/2.jpg)
X-ray Computed Tomography(CT)
– Also known as CAT Scan.
– Tomographic cross-sectional imaging
– Typically uses relatively high energy X-rays(120-140 kVp) filtered to include the highenergy part of the spectrum.
– Fan beams and thin slices (collimation!).
– A detector array is placed opposite a tube thatrevolves around the patient.
– The cross-section is reconstructed from theprojections.
![Page 3: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/3.jpg)
“Third Generation” CTTechnology
– Revolving array ofdetectors.
– Revolving X-ray tube.
– Moving bed allowsmultiple slices.
– Cabling harness usuallylimited the rotation ofthe detector array andtube to 180° to 360°
“Fourth Generation” CTTechnology
– Fixed array of detectors.
– Revolving X-ray tube.
– Can be constructedusing slip-rings,allowing continuoustube rotation.
– Simultaneous patientmotion and continuoustube revolution enableshelical CT scanning(also called spiral CT).
![Page 4: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/4.jpg)
CT
Spiral Computed Tomography
– AKA Helical CT
– The table is moved simultaneously with gantryrotation and X-ray exposure
– Helical data is interpolated to form conventionalprojections
– An entire volume is scanned in 30 seconds
– Equivalent to 30 individual slices
– Ideal for organs that move during respiration
![Page 5: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/5.jpg)
MRI
• Magnetic
• Resonance
• Relaxation– a.k.a. Nuclear Magnetic Resonance
– A big magnet, a microwave oven, a radioantenna, and a fast computer.
![Page 6: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/6.jpg)
MRI
– Acquire any plane or an entire volume
– Images generally 512x512 or 256x256 pixels
– Voxels as small as 0.5x0.5x2 mm, but variable
– Sometimes gaps in between slices
– 5-10 minutes for one sequence
– No absolute scale for the signal (10 bits)
Assembly diagram of a 1.5 Tcryostat vessel (Toshiba)
View of a 1.5 T diagnosticMRI magnet (GE Medical)
![Page 7: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/7.jpg)
Magnet Safety - (courtesy of GE Medical Systems)
![Page 8: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/8.jpg)
The Visible Human Project Data
• Multiple modalities– MRI
– X-ray CT
– Photographic cryosections
• Unique study in anatomy
• High spatial resolution
• Male: 17 GB, Female: 50+ GB
![Page 9: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/9.jpg)
CT Cryosection
MRI - PD MRI - T1 MRI - T2
Visible Human Data Acquisition
![Page 10: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/10.jpg)
Medicine in Virtual Reality
• CAD
• Telemedicine– filerooms
– image storage/retrieval
– EMR
– remote diagnosis/ treatment.
![Page 11: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/11.jpg)
Medicine in Virtual Reality(continued)
• Training / education
• Surgical Planning
• Computer assisted therapy
• Image guided therapy
• Treatment (e.g., mental health)
Visualization / Education
![Page 12: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/12.jpg)
Visualization / Education
Simulation / Training
![Page 13: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/13.jpg)
Simulation - Univ. of Colorado
Haptic Training Simulator - Univ. of Colorado
![Page 14: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/14.jpg)
Computer Assisted Therapy
Augmented Reality - BWH
![Page 15: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/15.jpg)
Augmented Reality - Harvard BWH
Image Guided Therapy
![Page 16: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/16.jpg)
Treatment - Georgia Tech
Faster Prettier
Handier Realer Modeling
AnyVirtual- World System
How To Make VR Work?
![Page 17: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/17.jpg)
Simulation vs. Interaction
Fidelity
Interactivity
VR
Animation
Simulation vs. Interaction
Realism
Speed
VR
JurassicPark
![Page 18: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/18.jpg)
Model Size: 1-100 Million Triangles
Virtual Reality - It Almost Works
• Swimming due to lag
• Limited precision– Poor registration with real world
• Limited model complexity
• Bad ergonomics
![Page 19: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/19.jpg)
Hardware Required for VR
• Image Generation: Speed, textures– PixelFlow (1995) 20 M textured, shaded tri/sec
– SGI (1998) 13-100 M textured, shaded tri/sec
• Image Delivery: See-through, resolution,wide angle– Virtual Research - V8
• Tracking: Lag, range, lag, precision– UNC optical ceiling tracker — 5.5 m x 7.5 m
640 x 480 Pixel, stereo, HMD
![Page 20: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/20.jpg)
Required Hardware (continued)
• Networking — Speed, usefulness models– Vistanet testbed for 1 Ghz fibre application
• Haptics: Fidelity, speed, flexibility– Sensable 1999: Phantom 6-degree-of-freedom
arm, electrical, 1 mm.
Haptic devices by Sensable
![Page 21: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/21.jpg)
Latency
• Frame rates are not latency.
• Delays are measured from end-to-end.
• Affects simulator sickness.
• Rates:– IBR (Siggraph 99): minimum JND = 7 msec.
– Haptics: minimum JND = 1 msec.
Precision
• Accuracy required in medicine: 1 mm?
• Computational precision? Error?
• Outcomes? Evaluation?
![Page 22: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/22.jpg)
Augmented Reality Ultrasound circa 1991
![Page 23: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/23.jpg)
Latency - some approaches
• Mechanical tracking
• Commercial hardware.
Precision - an Approach
• Video registration
• Predictive tracking
• Mechanical tracking
![Page 24: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/24.jpg)
Virtual Reality in Medicine
Terry S. Yoo, HPCC OfficeNational Library of Medicine, NIH
![Page 25: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/25.jpg)
Designing a Digital SurgicalSimulator for Interventional MRI
Terry S. Yoo, HPCC OfficeNational Library of Medicine, NIH
Acknowledgements
• Penny Rheingans, CSEE Dept.– Univ. of Maryland Baltimore County
• University of Mississippi Medical Center– Dr. S. Crawford, Dr. B. Harrison, Dr. G.
Dhillon.
• University of Mississippi Computer Science– A. Rodden, C. Bland, B. Fox
![Page 26: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/26.jpg)
Support
• The Institute for Technology Development
• Sun Microsystems
• GE Medical Systems
Minimally Invasive Surgery
• Surgery through small openings.
• Reduced trauma.
• Reduced chances for infection.
• Shortened recovery times.
• Shortened stays in ICU.
• Consider - minimally invasive knee surgery
![Page 27: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/27.jpg)
Interventional MRI
• Simultaneous imaging and surgery withMRI technology.
• Immediate 3D verification of proceduresuccess.
• Does not use ionizing radiation (x-rays).
• Better for patient and practitioner.
• Latest advance for physics in medicine.
NMR and Medicine: MRI
• A non-invasive cross-sectional imagingmodality.
• Does not employ ionizing radiation.
• Good soft-tissue definition.
• Advances in functional MRI allow imagingof physiology as well as anatomy.
• EPI techniques enable heat imaging.
![Page 28: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/28.jpg)
Limitations of Conventional MRIScanning Equipment
• Superconducting magnets– 10,000 Gauss = 1 Tesla
– Earth’s magnetic field = 0.5 Gauss
• Cryogen chambers required.
• Limited access to patient during procedures.
• Claustrophobia inducing environment.
Pros in MRI
• Non-ionizing radiation
• Good imaging characterisitics.
• Operates in acoustically opaqueregions of the body.
• Good soft-tissue definition.
• New advances in functional MRI allowimaging of physiology as well as anatomy.
![Page 29: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/29.jpg)
Cons in MRI
• Projectile or “missile effect.”
• Requires liquid helium.
• Radiofrequency and strong magnetic fieldscreate concerns for patients withpacemakers or other instruments.
• Image artifacts introduced by steel plates orother magnetically susceptible prostheses.(also scalpels, clamps, …)
Three Interventional Designs
• Philips - Conventional magnet– Long patient table, One end: Angiography suite
– Conventional 1.5T MRI system
• Siemens - Low Field magnet– Swing arm table, angiography suite
– 0.35T Open Fixed Field MRI system
• GE - Medium Field surgical magnet.
![Page 30: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/30.jpg)
Philips: Hybrid System
• Full Angiography suite (catheters).
• Higher field strength.– Use spin echo - not gradient echo - sequences
– Higher susceptibility - except when biopsyalong the B0 direction.
• Restricted access to patients in the bore.
• U Minnesota, and UCSF (planned).
U. Minnesota Reports
• 15-20 minutes for an intraoperative scan
• Diagnostic Tissue Rate.– IMR 80/80 cases (100%)
– Frame stereotaxy 129/134 cases (96%).
• Infection.– IMR = 1/80 (1.25%)
– OR = 2%
![Page 31: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/31.jpg)
U. Minnesota ReportsBrain Biopsy
• Occasionally discharge biopsy same day
IMR Conventional ORLength of Stay 3.3 Days 6.4 days
Cost/Charge Ratio 71.77% 74.10%
Cost reduction IMR 32%
Charge Reduction 29.60%
U. Minnesota ReportsRetreat Tumor Resection Rate
Adults IMR Conventional ORPrimary 0% 18%Recurrent 7% 45%
PediatricPrimary 0% 32%Recurrent 33% 50%
![Page 32: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/32.jpg)
GE Design: Open Magnet
• Based on Nb-Sn compounds – No cryogensrequired.
• Open configurations permit a variety ofscanning orientations.
• Patient access allows interventionalprocedures – surgery.
• Less confining environment offers patientsalternatives.
Interventional MRIaxial view
Interventional MRIoverhead view
![Page 33: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/33.jpg)
Cross-sectionalschematicof theopenmagnet
![Page 34: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/34.jpg)
![Page 35: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/35.jpg)
Why a Simulator?
• Rapid instrument and proceduredevelopment (outside the O.R.).
• Beyond surgical planning.– “No battle plan survives first contact with the
enemy.” -Wellington
• Develop the use of image guided therapies.
• Safety.
![Page 36: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/36.jpg)
![Page 37: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/37.jpg)
Floorplan for the new MRI/CT facility at UMMC
![Page 38: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/38.jpg)
Visualization Issues
• Exact GUI reconstruction
• Texture reflects radiologic data
• Surface rendering for anatomical references
• Dynamic (near-real-time) update
![Page 39: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/39.jpg)
Early view of theSurgical Simulatorlaboratory.
Infrared photodiode array
Sun Ultrasparc 2: consoleand simulation system
3D Tracking base unit
3D Tracking target
Software Design
• Generated GUI from SDK configurationfiles from GE Medical Systems.
• Leveraged existing visualization tools(VTK).
• Hand coded the serial interface to theFlashpoint™ 5000 tracker.
• Combined texture information with 3Dsurface renderings.
![Page 40: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/40.jpg)
Diagnostic Data (Surgical Plans)
Live Data
Volume Data
Slice Extraction Surface
Extraction
Geometry (Skin)
Geometry (Skull)
Geometry (Tumor)
Textured Polygon
3D Renderer 2D Renderer
Simulation Window Slice Window
Tracker Library
Tracked Instrument
Infrared Detector
Array
Infrared Patient Targets
IGT Flashpoint 5000 Infrared Tracking System
![Page 41: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/41.jpg)
Results
• Fast, dynamic simulation (10 fps) - fasterthan the actual scanner (.7 fps)
• Surgeons preferred the simulator forplanning. Lack of tissue dynamics limiteduse as a training tool.
• Anatomical references preferred forinexperienced users.
• Simulator use suggested tool modifications.
![Page 42: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/42.jpg)
Visualization Extensions
• Physical gap simulation (not completed).
• Adapted to texture based volume rendering.
• Direct rendering to the iMRI suite.
• Integration with the PACS network.
• Fused MRI and CT data.
• Segmentation, segmentation, segmentation.
Volume Rendering
• Requires better segmentation.
• Unlike CT data, MR data has notdirect mapping to density.
• Can use alternate pulse sequences tosuppress dermal fat and increase contrastbetween white and grey matter.– Inversion recovery
– Phase contrast angiography
![Page 43: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/43.jpg)
Lessons
• Dynamic control essential.
• Discard unwanted anatomy.
• MRI data, especially those collected withsurface coils represent significantchallenges to most visualization systems.
• Surface geometry is less essential than highfidelity reconstruction of radiologic images.
• Segmentation is critical.
![Page 44: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/44.jpg)
Discard Unwanted Anatomy
Original (surface) 98% decimated
(wireframe)(shaded surface)
Discard Unwanted Anatomy(continued)
Original (surface) 98% decimated(wireframe)
![Page 45: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/45.jpg)
MRI Challenges
MRI Challenges (continued)
![Page 46: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/46.jpg)
Segmentation
• Quality of the visualization hinges onsegmentation.
• Segmentation can be aided by registrationof data compiled from multiple modalities.
Visible Human Toolkits(watch this space)
• A new, 3-year research initiative insegmentation and registration by theNational Library of Medicine.
• Software consortium meets next week.
• Publicly available implementations ofsegmentation and registration algorithms.
• Open-source public software resource.
• No-cost licenses.
![Page 47: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/47.jpg)
Summary
• Simultaneous MR imaging and surgery.
• Clinical challenge is to make it effective inmedical care today.
• Engineering and clinical challenges in:– Materials Science
– Antenna and instrument design
– Pharmaceuticals
Summary (continued)
• Visualization research opportunities in:– Image processing.
– Real-time data processing.
– Dynamic interactive visualization techniques.
– Segmentation and Registration.• Deformable multimodal registration.
• Segmentation of non-homogeneous image data.
![Page 48: Virtual Reality in Medicine - Department of Computer Science › ~cohen › VW2000 › Lectures › VR_in_Medicine.bw.pdf · Virtual Reality in Medicine 16-17 March 2000 Johns Hopkins](https://reader033.vdocuments.site/reader033/viewer/2022052722/5f0c03c97e708231d433554e/html5/thumbnails/48.jpg)