Volume-Rendered
3D Helical CT
Boca Raton Regional Hospital is one of the first facilities in the country able to offer real-time 3D volume rendering, an exciting new technology enabling unparalleled imaging of complex data sets and anatomic information.
What is 3D Helical CT?
- Displays 3D spatial relationships in
a two-dimensional image
- Volume CT data set
- Sophisticated computer post-processing
Real-time 3D CT of
Pilon fracture of distal tibia
Role of
Helical CT in Orthopedic Imaging
What is 3D Helical CT?
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Role of
Helical CT in Orthopedic Imaging
CT Hardware
Requirements
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What is
Helical (Spiral) CT?
- X-ray production
- Simultaneous table & tube movement
- Produces volume data set
- Subsecond spiral acquisition- minimizes
motion artifact
- Anisotropic voxels (longer in the
z axis than in the transverse plane)
Surface Rendered 3D image
s/p 1st MPJ replacement arthroplasty utilizing a Swanson Silastic
Total Hinge Joint implant
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Surface Rendered 3D image s/p 1st MPJ replacement arthroplasty utilizing a Swanson Silastic Total Hinge Joint implant |
3D Surface
vs Volume-Rendering
<link
to source Radiographics article (Pretorius & Fishman)>
Shaded Surface Rendering
Shaded
Volume Rendering
- Shaded surface rendering algorithms
- only uses first defined voxel as the surface of the bone
- Displays gross 3D relationships
- Fails to display lesions hidden
beneath the bone surface
- Tend to demonstrate stair-step artifacts.
- Uses entire data set
- Conveys more information
- Contributions of each data set voxel
are summed
- May be viewed in any plane or projection
and in a range of opacity from transparent to opaque
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Computer
Hardware Requirements
- Real-time interactive display
- Eliminates need for editing prior
to 3D rendering
- Rapidly obtains clinically useful
images
- Expedites communication of results
- Anisotropic voxels interpolated
to create cuboid isotropic voxels
- Isotropic data mapped into appropriate
plane
- Rendering algorithm into 3D volume
- Requires considerable computer power
(Silicon Graphics Workstation)
Stereo 3D
Display
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Stereo 3D Display
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3D Volume
CT may alter management
- Those who might otherwise have received conservative treatment but become surgical candidates
- Those in whom urgent surgery is delayed in favor of later, definitive arthrodesis or arthroplasty
Complex
Fractures
- Talar and calcaneal injuries easily evaluated
- 3D mapping for preoperative planning
- Complex intra-articular fractures of the
distal tibia
- Immediate surgery vs later, definitive
arthroplasty
Real-time 3D CT of Calcaneus
fracture
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Post-operative
Imaging
CT and MR imaging limited due to artifact from implanted hardware Spiral CT with volume rendering able to compensate for streak artifact despite the presence of metal plates, pins, or prostheses. |
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Other Applications
- Endovascular Aortic
Stent Graft used for perctaneous repair of abdomial aortic aneurysm
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