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