Download - Medical Image Processing
CVIP LabThe University of Louisville
Medical Image Processing
M. Sabry HassounaM. Sabry Hassouna
Ph.D.Ph.D.Computer Vision & Image Processing Laboratory (CVIP)
Louisville, Kentucky
The study of medical imaging is concerned with
Interaction of all forms of radiation with tissue.
The development of appropriate technology to extract clinically useful information, usually in the form of an image from the observed technology.
Medical ImagingMedical Imaging
X-RayX-Ray
Nov 8, 1895 Wilhelm Konrad Röntgen reported discovery of new “rays” (Nobel Prize in physics in 1901).
Jan 13, 1896First clinical use of X-rays by 2 First clinical use of X-rays by 2 British doctors to find a needle British doctors to find a needle in a hand.in a hand.
Image Formation A beam of X-rays is directed through a patient
onto a film. The film provides a measure of the ray
attenuation in tissue.
+ Excellent for imaging bones.+ Excellent for imaging bones.
- No depth information, bad for soft tissue, excessive radiation- No depth information, bad for soft tissue, excessive radiation
Sample X-Ray SlicesSample X-Ray Slices
Computed Tomography (CT)Computed Tomography (CT)
Nov 8, 1895 G. Hounsfield (computer expert) and A.M Cormack (physicist)(Nobel Prize in Medicine in 1979).
Image FormationThe object is viewed from a number of different angles and then a cross-sectional image of it can be computed (reconstructed).
+ Provide 3D anatomical information+ Provide 3D anatomical information
+ Preserves topology (bones)+ Preserves topology (bones)
- Excessive radiation- Excessive radiation
- Not good for all soft tissues- Not good for all soft tissues
Sample CT SlicesSample CT Slices
CT Acquisition TechniquesCT Acquisition Techniques
slice-by-slice scanning
Spiral (volume) scanning (Very Fast) 3D Reconstruction
Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI)
1952F. Bloch and E. Purcel, extended by R. Ernst)(Bloch & Purcel: Nobel Prize in Physics in 1952)(Ernst: Nobel Prize in Chemistry in 1991)
Image Formation- Hydrogen nuclei (protons) under a strong magnetic field spin in phase with one another and align with the field.- Relaxed protons induce a measurable radio signal.
+ Main modality for image guided surgery.+ Superb ability to discriminate between subtle differences in tissue characteristics.+ Very safe.- Less accurate for bone scanning.
Sample MRI SlicesSample MRI Slices
Ultrasound (US)Ultrasound (US)
1979: Samuel H. Maslak
Image FormationAn ultrasonic energy is propagated into the patient from a transducer placed on the skin and back-scattered echo signal is recorded by the same transducer.
+ Noninvasive+ Clean & safe+ In-expensive- Noisy- Gas filled and bony structures cannot be imaged because they absorb ultrasound waves.
Positron Emission Tomography (PET)Positron Emission Tomography (PET)
1998-2001: Dr. David Townsend and Dr. Ron Nutt.
Image Formation- Detection of radiation from the emission of positrons.
+ Valuable technique for some diseases and disorders.+ Amount of radiation is small- Invasive (inject radioactive material)
Magnetic Resonance Angiography (MRA)
Magnetic Resonance Angiography (MRA)
Image FormationImaging the blood vessels (moving spins) using MRI scanner.
TOF (time-of-flight)TOF (time-of-flight)
PCA (phase contract angiography)PCA (phase contract angiography)
(CEA) (contrast enhanced angiography)(CEA) (contrast enhanced angiography)
(CTA) (computer tomography angiography)(CTA) (computer tomography angiography)
(DSA) (digital subtraction angiography)(DSA) (digital subtraction angiography)
DSADSA CTACTA TOFTOF
Medical Image ProcessingMedical Image Processing
Data ProcessingData Processing
1. Preprocessing
Filtering, registration
2. Detection
Finding objects (nodules, polyps, organs)
3. Segmentation
Exact delimitation of objects
4. Analysis
Measurement (volume, curvature)
5. Classification/diagnoses
PreprocessingPreprocessing
Original Enhanced
DetectionDetectionFind location of objects of interest without prior knowledge about their location/existence
• Bones• Organs• Polyps in colon• Nodules in lungs
SegmentationSegmentationExactly delimitate objects, once they are detected.
- Vessels- Liver- Cardiac imaging (left ventricle)- Brain
AnalysisAnalysis
• Measurement Volume - growth Vessel stenosis
• Functional imaging Stroke Cardiac perfusion Tumor perfusion
• Cardiac function LV motion Injection fraction
Classification / DiagnosesClassification / Diagnoses
• Comparison to developed atlases• Use of knowledge databases• Classify as normal/abnormal (brain) • Classify lung nodules as benign/malignant• Determine cancer/non-cancer