Introduction 536 2013

This presentation has prepared by taking material from various books/journal papers for teaching a course in MEDICAL IMAGING. It has no commercial value and is only for reference purpose.

EE-536 MEDICAL IMAGING Credit 4 L-3, T-1, P-0

S. No. Titles Author year

1 Fundamentals of Medical Imaging

Paul Suetens 2009

2 Introduction to Medical Imaging: Physics, Engineering and Clinical Applications

Nadine Barrie Smith 2010

3 The Physical Principles of Medical Imaging, 2nd ed

Perry Sprawls, Ph.D 2010

4 The Essential Physics of Medical Imaging (2nd Edition)

Jerrold T. Bushberg 2002

5 An Introduction to the Principles of Medical Imaging

Chris Guy

2005

6 Digital Image Processing for Medical Applications

Geoff Dougherty 2009

7 Digital Image Processing Gonzalez, Rafael C.; Woods, Richard E.

2009

8 Fundamentals of Electronic Image Processing

Arthur R Weeks, Jr. SPIE / IEE Series 1996

1998

9 Machine Vision Ramesh Jain, Rangachar Kasturi &Others

1995

List of Books

2010 2011

Medical Imaging

1. Introduction to Medical Imaging 2. (i) History of Medical Imaging (ii) EM Spectrum 3. Medical Imaging Modalities 4. X-Ray, Interaction with matter 5. X-Ray equipment, detectors, film, Screen, Image quality 6. Dual Energy X-rays 7. Fluoroscopy 8. Mammography

9. Angiography 10. X-Ray Computed Tomography 11. 2 D and 3 D Imaging 12. MRI Introduction, qualitative description 13. Brain tumors and types 14. Image quality, equipment, clinical use-1 15. Image quality, equipment, clinical use-2 16. NMI, SPECT, PET 17. Image quality, equipment, clinical use-1 18 Image quality, equipment, clinical use-2 19. Ultrasound Imaging, Introduction, Physics of acoustic waves

20. Generation & detection, gray scale imaging 21. Doppler Imaging 22. Image quality, equipment, clinical use-1 23. Image quality, equipment, clinical use-2 24. Basics of Image enhancement in space & frequency domain -1 25. Basics of Image enhancement in space & frequency domain-2 26. Feature extraction, first order statistics and second order statistics 27. Feature extraction: Higher order statistics

28. Texture analysis 29. Morphological Analysis 30. Enhancement techniques Ridgelet Transform 31. Curvelet Transform 32. Various noise models 33. Image Compression 34. Despecke filtering 35. Cluster based Medical Image segmentation 36. Ultrasound Liver Image Classification I 37. Ultrasound Liver Image Classification II

38. Segmentation & registration of MRI 39. Detection and Classification of Mammography Images 40. SVM Based Classification of mammography 41. Reduction of blocking artifacts 42. Conclusions

MILESTONES MEDICAL DIAGNOSTIC IMAGING

Date Development of Discovery 400 BC Disease concept introduced by Greek physician

Hippocrates. 1612 Medical Thermometer devised by Italian

physician Sanctorius. 1660 Light Microscope developed by Dutch naturalist

Antohj van Leeuwenhoek. 1810 Stethoscope invented by French physician Rene

Laennec. 1850- 1900

Germ theory of disease proposed by French scientist Louis Pasteur and developed by German bacteriologist Robert Koch.

1895 X-rays discovered by German physicist Wilhelm Conrad Roentgen. He also produced the first x-ray picture of the body(his wifes hand) in 1895.

1900 Chest x-ray, widespread use of the chest x-ray made early detection of tuberculosis (which was the most common cause of death) a reality.

1906 X-ray contrast medium. First contrast filled image of the renal system (kidneys).

1910 Barium sulfate introduction of as contrast agent for gastro-intestinal diagnosis.

1910-1912

Theory of Radioactivity published by Marie Curie and investigation of x-ray radiation for patient therapy (e.g. treatment of cancer).

1906 Electrocardiograph (ECG) invented by Dutch physiologist Willem Einthoven to monitor and record the electric signature of the heart.

1924 Radiographic imaging of the gallbladder, bile duct and blood vessels for the time.

1929 Cardiac catheterization first performed by Forssmann on himself.

1932 Transmission electron microscope (TEM) Constructed by German scientists Max Knoll and Ernst Ruska.

1945 Coronary artery imaging. Visualization of (blood vessels that feed the heart).

1950 Nuclear Medicine applied imaging the kidneys, heart, and skeletal system.

1955 X-ray image Intensifier-Television units to allow dynamic x-ray imaging of moving scenes. These fluoroscopic movies provided new information of the beating heart and its blood vessels.

1955 Panoramic x-ray images of the entire jaw and teeth.

1957 Fiber endoscopy pioneered by South African-born physician Basil Hirschowitz at the University of Michigan.

1960 Ultrasound imaging is developed to look at the abdomen and kidneys, fetal body, carotid blood vessels and heart.

1970 X-ray mammography finds widespread application in imaging the breast.

1972 Computed Tomography (CT) scanning invented by British engineer Godfrey Hounsfield of EMI Laboratories, England, and South African born physicist Allan Cormack of Tufts University, Massachusetts.

1976 Coronary Angioplasty was introduced by surgeon Andreas Gruentzig at the University Hospital, Zurich, Switzerland. This technique uses x-ray fluoroscopy to guide the compression of plaques and minimize the dangerous constriction of the heart vessels.

1978 Digital radiography: the TV signal from the x-ray system is converted to a digital picture which can then be enhanced for clearer diagnosis and stored digitally for future review.

1980 Magnetic Resonance Imaging (MR) of the brain was first done on a clinical patient. MRI was developed by Paul Lauterbur and scientists at Thorn-EMI Laboratories, England, and Nottingham University, England.

1984 3-Dimensional image processing using digital computers and CT or MR data, three dimensional images of bones and organs were first made.

1985 Clinical Positron Emission Tomography (PET) scanning developed by scientists at the University of California.

1985 Clinical Networks were first implemented to allow digital diagnostic images to be shared between physicians via computer network, allowing a doctor in Boston to review a CT examination from a patient in Beijing, China.

1989 Spiral CT allows fast volume scanning of an entire organ during a single, short patient breath hold of 20 to 30 seconds. Spiral CT had caused a renaissance in CT and lead the way to significant developments like CT Angiography.

1989 MR Angiography developed and clinically available to allow non-imaging of the blood vessels without radiation or contrast injection.

1993 Echo Planar MR Imaging (EPI) developed and clinically available to allow MR systems to provide early detection of acute stroke. EPI also makes possible functional imaging, for instance of brain activity allowing doctors to investigate the function of different centers of the mind.

1993 Open MRI Systems developed to allow MR scanning of severely claustrophobic or obese patients who could not tolerate convention MR imaging in a close bore system.

Fields using DIP Late 1960s & early 1970, use of DIP techniques

in Medical imaging Remote earth resources observations Astronomy Computerized Axial Tomography in early 1970s by Sir Godfrey N. Hounsfield & Prof Allan M. Cormack ( 1979 Nobel Prize in Medicine) Whereas X-ray was discovered in 1895 by Wilhelm Conrad Roentgen ( 1901 Nobel Prize)

X-Ray

18

INFRARED

19

DIMENSIONALITY OF DIGITAL IMAGE

Dimension 2

Dimension 1

20

Image Processing Examples

21


22


23


24

Classification of Images

Electromagnetic Energy Spectrum Acoustic (sound) Electron Microscopy Synthetic-Computer generated

Gamma-Ray Imaging

Used in Nuclear Medicine & Astronomical Observations

In nuclear medicine To inject radioactive isotope that emits

gamma rays as it decays Images are formed from emission collected by

gamma ray detectors Used for bone pathology such as infection or

tumor

NUCLEAR MEDICINE FUNCTIONS OF ORGANS

Abdomen to check gastrointestinal bleeding Brain to look for tumors Blood blood cell disorders Breast breast cancers Hepatobiliary gallbladder bile duct functions Heart coronary artery disease Kidney renal functions Liver cirosis or metastatic cancers Lungs pulmonary functions blood clot etc

NUCLEAR MEDICINE or RADIONUCLIDE

Functional and anatomical information about organs

Fused image of Nuclear Med & MR acquisition

MR gives excellent anatomical details SPECT gives excellent functional

Positron Emission Tomography

Same principle as that of X-Ray tomography In place of X-Rays, radioactive isotopes are

used that emits Positrons as it decays When positron meets an electron, both are

annihilated and two gamma rays are given off Gamma rays are detected and tomography

image is created In image shown here displays a visible tumor in

lungs

SOME APPLICATIONS OF PET

Study of epilepsy evaluation of stroke Study of dementia alzheimers parkinsons Brain tumors Coronary artery disease to study of transient

ischemia Differentiation between active tumor growth

and necrotic ie dead

SPECT

Single positron emission computed tomography It uses gamma camera which can rotate and

computer reconstruction similar to PET PET may be more sensitive than SPECT but PET

scanners are more costly

X-Rays

Analog X-Rays Digital X-Rays Dual Energy X-Rays Fluoroscopy CT Imaging Angiography Mammography

Photographic film affected by x-rays Digital x-rays use

Digitizing x-rays film X-rays after passing the body falls on

phosphor screen to convert x-rays to light and than on light sensitive detectors

Angiography Contrast enhancement radiography Used to obtain images of blood vessels A catheter is inserted into blood vessel and

guided to the area to be studied An x-ray contrast media is inserted by catheter This enhances the contrast of blood vessels to

see irregularities & blockages Image subtraction is used to enhance further

contrast of blood vessels

CONTRAST MATERIAL substance that has a different opacity from soft tissue on

radiography or computed tomography. Includes: Barium or water, for gastrointestinal tract opaque. Iodine in water, for arthrography. Water soluble iodine, to make blood vessels

opaque; to demonstrate the inner structures of the urinary tract (kidneys, ureters and bladder); and to outline joints (the spaces between two bones).

Iodine mixed with water or oil to evaluate the fallopian tubes and lining of the uterus.

Sterile saline (salt water) is used during hysterosonography.

ANGIOGRAPHY EQUIPMENT

X-RAY RADIOGRAPHY X-ray Source

X-ray Screen Film X-ray Screen

3-D Object or Patient

2-D Projection Image

Anti-scatter Grid

CHEST RADIOGRAPH

Computerized Tomography

3-D capabilities Numerous slices are taken to generate

images Images are created using mathematical

model of the body and a computer

3-D CONFIGURATION

y

x

z X-Y Slices

x

z

y

Iin(x; y,z) Iout(x; y,z)

(x,y; z)

11

22 92

15

12 42 52 62 72 82

FIRST GENERATION SCANNERS

CT SCANNER

Ring of Detectors

Source

Source Rotation Path

X-rays

Object

CT CHEST IMAGES

FLUOROSCOPY

Flouro (short) scopy x-ray procedure for real time digital acquisition

DIGITAL X-RAYS

Lower dose of x-ray can give same high resolution as with film x-ray

Image can be enhanced by DIP Can be stored & retrieved Is being used in breast imaging and biopsy

ULTRAVIOLET BAND Application of ultraviolet light

This includes lithography, industrial inspection, microscopy, lasers, biological imaging & astronomical observations

Used in fluorescence microscopy Mineral fluorescence when UV light is focused on it UV itself is not visible but when a photon of UV radiations

collide with electron in an atom of a fluorescent material, it elevate the electron to a higher energy level

Excited electron relaxes to lower level and emits light in the form of lower energy photons in visible (red) light region

Emission light reaches the eye or detector

Visible & Infrared Bands

Light microscope Micro-inspection of material characterization,

pharmaceuticals, remote sensing like NASAs LANDSAT etc

Microwave Band

RADAR RADAR waves can penetrate clouds, and

can see through vegetation, ice & dry sand It works like a flash camera ie it provides

its own illumination ie microwave pulses and take a snap shot.

It uses an antenna and digital computer processing

INFRARED VIDEO IMAGING

Radio Band

Medicine & astronomy MRI

MAJOR MRI SCANNER VENDORS

Siemens Sonata

General Electric CV/i

Philips Intera CV

MRI Uses Three Magnetic Fields

Static High Field (B0) Creates or polarizes signal 1000 Gauss to 100,000 Gauss

Earths field is 0.5 G Radiofrequency Field (B1)

Excites or perturbs signal into a measurable form On the order of O.1 G but in resonance with MR signal RF coils also measure MR signal Excited or perturbed signal returns to equilibrium

Important contrast mechanism Gradient Fields

1-4 G/cm Used to image: determine spatial position of MR signal

THERMOGRAPHY Any object above absolute zero will radiate

electromagnetic radiations/energy to an extent governed by its radiant emitance

the use of thermography in cancer detection is based upon the assumption that a temperature difference exists between a malignant tumor and the surrounding tissue.

ULTRASOUND

medical

ULTRASOUND

ULTRASOUND

Ultrasound uses the transmission and reflection of acoustic energy.

prenatal ultrasound image clinical ultrasound system

ULTRASOUND

A pulse is propagated and its reflection is received, both by the transducer.

Key assumption: - Sound waves have a nearly constant velocity of ~1500 m/s in

H2O. - Sound wave velocity in H2O is similar to that in soft tissue. Thus, echo time maps to depth.

ULTRASOUND: RESOLUTION AND TRANSMISSION FREQUENCY

Tradeoff between resolution and attenuation - higher frequency shorter wavelength higher

attenuation Power loss:

Typical Ultrasound Frequencies: Deep Body 1.5 to 3.0 MHz Superficial Structures 5.0 to 10.0 MHz e.g. 15 cm depth, 2 MHz, 60 dB round trip

MHz cmdB 1

Why not use a very strong pulse? Ultrasound at high energy can be used to

ablate (kill) tissue. Cavitation (bubble formation) Temperature increase is limited to 1 C for

safety.

FRACTAL IMAGING

Computer generated images Iterative reproduction of a basic pattern

according to some mathematical rules Flight simulators, medical training

CLINICAL APPLICATIONS

Chest Abdomen Head X-Ray/ CT

+ widely used + CT - excellent

needs contrast + CT - excellent

+ X-ray - is good for bone CT - bleeding, trauma

Ultrasound no, + heart

+ excellent problems with gas

poor

Nuclear + extensive use in heart

Merge w/ CT + PET

MR

+ growing cardiac applications

+ minor role + standard

CLINICAL APPLICATIONS

Cardiovascular Skeletal / Muscular X-Ray/ CT

+ X-ray Excellent, with catheter-injected contrast

+ strong for skeletal system

Ultrasound

+ real-time + non-invasive + cheap but, poorer images

not used + Research in elastography

Nuclear + functional information on perfusion

+ functional - bone marrow

MR + getting better High resolution Myocardium viability

+ excellent

Conventional X-ray X-ray Computed Tomography (CT)

Radioisotope Imaging (Nuclear Medicine)

Magnetic Resonance Imaging (MRI)

Ultrasound Imaging (1 to 10 MHz)

Positron Emission Tomography (PET)

Projection/Tomography

Projection Tomography Both Tomography Tomography Tomography

Mainly Anatomical / Functional

Anatomical Anatomical Functional Both Both Functional

Interventional options?

Yes No No Possible Yes No

Maximum imaging depth in soft tissue

Metres Metres Body thickness Body thickness Body thickness Body thickness

Spatial resolution in plane of imaging (typical)

0.1 mm 0.25 mm 5 to 10 mm 0.5 mm 0.5 mm 5 to 10 mm

Slice thickness (typical)

n/a 1 to 5 mm n/a or 5 to 10 mm 3 to 10 mm 1 mm 10 mm

Safety Ionising radiation leads to a radiation dose

Ionising radiation leads to a higher radiation dose than for conventional x-rays

Ionising radiation leads to a moderately higher radiation dose than for conventional x-rays

A range of hazards arising from strong and time varying electromagnetic fields.

Thermal effects and cavitations

Ionising radiation leads to a moderately higher radiation dose than for conventiona x-rays

Examination time Short Medium Long Long Medium Long Physical property of tissue associated with image formation

Linear attenuation coefficient

Linear attenuation coefficient

Tracer isotope is involved in metabolic process; measure concentration

Proton density and nuclear magnetic resonance relaxation times.

Primarily acoustic impedance: differences lead to reflections at boundaries

Tracer isotope is involved in metabolic process; measure concentration

Relative capital cost*

Low Fairly high Fairly high High Medium High

Relative cost per patient study*

Low Medium Medium to high High Low High

Comments Interventional studies such as cardiac catheterisation take longer and are costlier than radiographic studies

May be called CAT (Computerized axial tomography). Current interest in multi-detector CT.

Some gamma camera systems also have PET capability, but these have lower sensitivity than dedicated PET systems

Open systems or special facility needed for intra-operative use. Tailored sequences used for functional measures.

Blocked by bone. The Doppler effect is used for measuring the velocity of blood flow

A cyclotron is used to produce specia isotopes; this must be located close by Current interest in combined CT/PET systems and PET/MR

High frequency ultrasound

Fluorescence microscopy

Optical coherence tomography

In vivo confocal microscopy

Spectro-photometric intracutane-ous analysis

Diffuse optical tomography

Terahertz pulsed imaging

High resolution MRI

Projection/Tomography

Tomography Projection Tomography Tomography Projection Tomography Both Tomography

Mainly Anatomical / Functional

Anatomical Functional Anatomical Anatomical Both Functional Both Anatomical

Maximum imaging depth in soft tissue

4 mm 0.5 mm 2 to 3 mm 400 m 2 mm 15 cm Few mm cm

Spatial resolution

20 m 1 m 10 m 2 to 5 m Up to 10 m 1 to 3 mm 350 m 100 m

Depth resolution

9 m n/a 5 to 15 m 0.5 m n/a 1 to 3 mm 40 m 100 m

Safety Thermal effects and cavitations

May involve administration of fluorophores.

Consult special guidelines regarding use in eye

Consult special guidelines regarding use in eye

Thermal effects

Thermal effects

Hazards from strong and time varying electromag-netic fields

Physical property of tissue associated with image formation

Primarily acoustic impedance: differences lead to reflections at boundaries

Decay time of fluorescence induced by laser light, plus spectrum and intensity, give molecular envir

Refractive index. Interferometric techniques used to infer time of flight

Uses reflected light or fluorescence

Effect of the skins chromophores(haemoglobin, melanin, collagen, dermal melanin)

Refractive index and scattering, chromophore content and absorption

Complex refractive index affecting pulses of radiation.

Proton density and nuclear magnetic resonance relaxation times

Comments 20-200 MHz. High frequency Doppler under development

e.g. FLIM Fluorescence Lifetime Imaging. Visible light.

OCT. Can be used endo-scopically. Visible light.

Accessible tissue surfaces, planes parallel to surface. Visible light.

SIAscopy analytical version of dermatoscopy or ELM. Visible light & NIR.

Monitor tissue and blood oxygenation levels. Near infrared (NIR).

Also spectro-scopy. mm- wave imaging is a passive technique at similar frequency.

Using special small coils in a 1.5-3T whole body scanner.

Slide Number 1EE-536 MEDICAL IMAGINGSlide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8MILESTONES MEDICAL DIAGNOSTIC IMAGINGSlide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Fields using DIPSlide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Classification of Images Slide Number 26Slide Number 27Slide Number 28Gamma-Ray ImagingNUCLEAR MEDICINE FUNCTIONS OF ORGANSNUCLEAR MEDICINE or RADIONUCLIDEPositron Emission TomographyPETSOME APPLICATIONS OF PETSPECTX-RaysSlide Number 37AngiographyCONTRAST MATERIALANGIOGRAPHY EQUIPMENTX-RAY RADIOGRAPHYCHEST RADIOGRAPHComputerized Tomography3-D CONFIGURATIONFIRST GENERATION SCANNERSCT SCANNERCT CHEST IMAGESSlide Number 48FLUOROSCOPYDIGITAL X-RAYSULTRAVIOLET BANDVisible & Infrared BandsMicrowave BandINFRARED VIDEO IMAGINGRadio BandSlide Number 56MAJOR MRI SCANNER VENDORSMRI Uses Three Magnetic FieldsTHERMOGRAPHYULTRASOUNDULTRASOUNDULTRASOUNDULTRASOUNDULTRASOUND: RESOLUTION AND TRANSMISSION FREQUENCYSlide Number 65FRACTAL IMAGINGCLINICAL APPLICATIONS CLINICAL APPLICATIONS Slide Number 69Slide Number 70

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Introduction 536 2013