3-D
3-D IMAGING IN MEDICINE IS A METHOD IN WHICH A SET OF DATA IS COLLECTED FROM A 3-D OBJECT, PROCESSED BY A COMPUTER, AND DISPALAYED ON A 2-D COMPUTER MONITOR TO GIVE THE ILLUSION OF DEPTH.
APPLICATIONS OF 3-D IN RADIOLOGY
RAD. THERAPY CRANIOFACIAL IMAGING ORTHOPEDICS NEUROSURGERY CARDIOVASCULAR SURGERY ANGIOGRAPHY MRI ENDOSCOPY (VIRTUAL)
RAD. THERAPY
CRANIO-FACIAL IMAGING
ORTHOPEDICS
ANGIOGRAPHY
NEUROSURGERY
VIRTUAL IMAGING
THE GENERATION OF 3-D OBJECT USING COMPUTER SOFTWARE IS CALLED MODELING
EXTRUSION
IS A MODELING TECHNIQUE THAT GENERATES A 3-D OBJECT FROM A 2 –D PROFILE
ON THE COMPUTER SCREEN.
EXTRUSION
PIXEL AREA
A
B
A= WIDTH B= HEIGTH
AREA OF THE PIXEL = A x B
VOXEL VOLUME
A
B
C
A= WIDTH B= HEIGTH
C-DEPTH (SLICE THICKNESS)
VOLUME OF THE VOXEL = A x B x C
DATA ACQUSITION FOR 3-D
CONVENTIONAL SLICE BY SLICE
VOLUME DATA ACQUSITION
PROBLEMS WITH CONVENTIONAL SLICE BY SLICE ACQUISITION IN 3-D GENERATION
MOTION - STAIR-STEP ARTIFACT
MIREGISTRATION
STAIR-STEP ARTIFACT
SEVER STAIR-STEP ARTIFACT
PROCESSING FOR 3-D
SEGMENTATION TRESHOLDING OBJECT DELINEATION RENDERING
SEGMENTATION
PROCESSING TECHNIQUE USED TO IDENTIFY THE STRUCTURE OF INTEREST IN A GIVEN IMAGE. IT DETERMINES WHICH VOXEL ARE PART OF THE OBJECT AND SHOULD BE DISPLAYED AND WHICH ARE NOT AND SHOULD BE DISCARDED.
SEGMENTATION
TRESHOLDING
METHOD OF CLASSIFYING THE TYPES OF TISSUES REPRESENTED BY EACH OF THE VOXELS. CT NUMBER IS USED TO DETERMINE THIS.
TRESHOLDING (IN SEGMENTATION)
DELINEATION
BOUNDARY EXTRACTION
VOLUME EXTRACTION
DELINEATION
RENDERING
3-D IMAGE IS TRANSFORMED INTO SIMULATED 3-D IMAGE SO IT CAN BE DISPLAYED ON THE 2-D MONITOR.
RENDERING TECHNIQUES
SURFACE RENDERING – SHADED SURFACE DISPLAY (SSD)
VOLUME RENDERING
SURFACE RENDERING-SSD
SIMPLER OF THE TWO METHODS. DISPLAYS THE IMAGE ACCORDING TO ITS CALCULATIONS OF HOW THE LIGHT RAYS WOULD BE REFLECTED TO THE VIEWERS EYES.
COMPUTER CREATES INTERNAL REPRESENTATION OF SURFACES
ADVANTAGE OF SSD
NOT MUCH COMPUTING POWER REQUIRED
ONLY CONTOUR INF IS USED
DISADVANTAGES OF SSD
INFO OF STRUCTURES INSIDE OR BEHIND THE SURFACE IS NOT DISPLAYED!!
SSD
SURGERY USING SSD
VOLUME RENDERING
SOPHISTICATED TECHNIQUE. 3-D IMAGES HAVE BETTER QUALITY THAN IN SURFACE RENDERING. USES ENTIRE DATA SET FROM 3-D SPACE. IT REQUIRES MORE COMPUTING POWER.
ADVANTAGES OF VOLUME RENDERING (VR) UNLIKE SSD, VOLUME RENDERING
ALLOWS SEEING THROUGH SURFACES. IT ALLOWS THE VIEWER TO SEE BOTH INTERNAL AND EXTERNAL STRUCTURES.
DISADVANTAGE/S
IT REQUIRES GREAT COMPUTING POWER – SOPHISTICATED COMPUTER EQUIPMENT
VR
VR
VR
MAXIMUM INTENSITY PROJECTION VOLUME RENDERING 3-D
TECHNIQUE THAT IS NOW FREQUENTLY USED IN CTA ( CT ANGIO) IT USES LESS THAN 10% OF DATA IN 3-D SPACE. IT DOES NOT NEED SOPHISTICATED COMPUTING.
IT ORIGINATED IN MRA
MIP ALLOWS ONLY THE VOXEL WITH THE BRIGHTEST VALUE TO BE SELECTED
MIP CAN ALSO BE DISPLAYED IN RAPID SEQUENCE- CINE
ADVANTAGES OF MIP
NO NEED FOR SOPHISTICATED COMPUTER HARDWARE- IT USES LESS THAN 10% OF DATA
DISADVANTAGE/S OF MIP
ARTIFACT- STRING OF BEADS
NO SUPERIMPOSED STRUCTURES DEMONSTRATION
MIP IN MRI
MIP OF THE HEAD???
MIP
MIP
COMPARISON OF 3-D TECHNIQUES
DEPICTION OF 3-D RELATIONSHIP IN 3-D TECHNIQUES
SSD – GOOD MIP – FAIR VR - GOOD
EDGE DELINEATION
SSD – GOOD MIP – GOOD VR - FAIR
VESSEL LUMEN DEPICTION
SSD – NO MIP – 1 PIXEL THICK VR - YES
% OF DATA USED
SSD - < 10% MIP < 10% VR UP TO 100%
ARTIFACTS
SSD – MANY FALSE SURFACES MIP – MIP ARTIFACT VR - FEW
CT WORKSTATION
3-D WORKSTATION FEATURES MPR- MULTIPLANAR RECONSTRUCTION TRANSPARENCY VISUALIZATION SURFACE RENDERING SLICE PLANE MAPPING SLICE CUBE CUTS MIP 4-D ANGIO DISARTICULATION VIRTUAL REALITY
MPR
TRANSPARENCY
CUBE SLICE CUT
4-D
DISARTICULATION
VIRTUAL REALITY