Download Proposal - The University of Texas at Arlington

ELECTRICAL ENGINEERING
DEPARTMENT
Spring 2012
EE 5359-002 (DE) – Multimedia Processing
Project Report On
MEDICAL IMAGING
GUIDED BY: DR. K.R.RAO
SUBMITTED BY:
Anuja Kulkarni (1000722132)
MEDICAL IMAGING
ABSTRACT
Medical imaging[1] as the name suggests is the technique and process used to
create images of parts and functions of human body for clinical purposes. It is a medical
procedure seeking to reveal, diagnose or examine disease.
As a discipline, it is part of biological imaging and incorporates radiology, nuclear medicine,
investigative radiological
sciences, endoscopy,
(medical) thermography,
medical
photography and microscopy (e.g. for human pathological investigations). As a field of
scientific investigation, medical imaging constitutes a sub-discipline of biomedical
engineering, medical physics or medicine depending on the context.
This project mainly covers three topics of medical imaging i.e. creation of 3D images,
compression of medical images and non-diagnostic imaging, its evaluation and
implementation.
List of acronyms
CAT - Computed Axial Tomography
CT - Computed Tomography
DICOM - Digital Imaging and Communications in Medicine
EEG - Electroencephalography
EKG - Electrocardiography
fMRI- Functional Magnetic resource imaging
JFIF- JPEG File Interchange Format
JPIP- JPEG 2000 Interactive Protocol
MEG - Magnetoencephalography
MRI - Magnetic Resonance Imaging
NMR- Nuclear Magnetic Resonance
RF- Radio Frequency
Introduction
Medical imaging [1]is the technique and process used to create images of the human
body for clinical purposes. Although imaging of removed organs and tissues can be
performed for medical reasons, such procedures are not usually referred to as medical
imaging, but rather are a part of pathology.
As a discipline and in its widest sense, it is part of biological imaging and
incorporates radiology, nuclear medicine, investigative radiological sciences, endoscopy,
medical photography and microscopy.
Measurement and recording techniques which are not primarily designed to produce images,
such as1. Electroencephalography (EEG)
2. Magnetoencephalography (MEG)
3. Electrocardiography (EKG)
and others but which produce data susceptible to be represented as maps (i.e. containing
positional information), can be seen as forms of medical imaging.
Up until 2010, 5 billion medical imaging studies have been conducted worldwide [1].
Radiation exposure from medical imaging in 2006 made up about 50% of total ionizing
radiation exposure in the United States.[1]
There are two types of medical imaging, they are1. Invisible light medical imaging
2. Visible light medical imaging
In the clinical context, "invisible light" medical imaging is generally equated to radiology or
"clinical imaging" and the medical practitioner responsible for interpreting the images is
a radiologist.
"Visible light" medical imaging involves digital video or still pictures that can be seen
without special equipment. Dermatology and wound care are two modalities that utilize
visible light imagery. Diagnostic radiography designates the technical aspects of medical
imaging and in particular the acquisition of medical images. The radiographer or radiologic
technologist is usually responsible for acquiring medical images of diagnostic quality,
although some radiological interventions are performed by radiologists. While radiology is an
evaluation of anatomy, nuclear medicine provides functional assessment.
As a field of scientific investigation, medical imaging constitutes a sub-discipline
of biomedical engineering, medical physics or medicine depending on the context: Research
and development in the area of instrumentation, image acquisition (e.g. radiography),
modelling and quantification are usually the preserve of biomedical engineering, medical
physics and computer science; Research into the application and interpretation of medical
images is usually the preserve of radiology and the medical sub-discipline relevant to medical
condition or area of medical science i.e neuroscience, cardiology, psychiatry, psychology,
etc. under investigation.
Medical imaging is often perceived as the set of techniques that noninvasively produce
images of the internal aspect of the body. In this restricted sense, medical imaging can be
seen as the solution of mathematical inverse problems. This means that cause is inferred from
effect. In the case of ultra sonography the probe consists of ultrasonic pressure waves and
echoes inside the tissue show the internal structure. In the case of projection radiography, the
probe is X-ray radiation which is absorbed at different rates in different tissue types such as
bone, muscle and fat. [2]
The term non-invasive is a term based on the fact that following medical imaging modalities
do not penetrate the skin physically. But on the electromagnetic and radiation level, they are
quite invasive. From the high energy photons in X-Ray computed tomography, to the 2+
Tesla coils of an MRI device, these modalities alter the physical and chemical environment of
the body in order to obtain data.
Imaging Technologies:
1. Radiography [5]
Two forms of radiographic images are in use in medical imaging; projection
radiography and fluoroscopy. [6]
Fluoroscopy produces real-time images of internal structures of the body in a similar
fashion to radiography, but employs a constant input of x-rays, at a lower dose rate.
Figure 1 shows an example of digital radiography i.e fluoroscopy
Projectional radiographs, more commonly known as x-rays, are often used to
determine the type and extent of a fracture as well as for detecting pathological
changes in the lungs.
Figure 1: Digital radiography [7]
2. Magnetic Resonance Imaging (MRI)
A magnetic resonance imaging instrument [8] (MRI scanner), or "nuclear magnetic
resonance (NMR) imaging" scanner as it was originally known, uses powerful
magnets to polarise and excite hydrogen nuclei (single proton) in water molecules in
human tissue, producing a detectable signal which is spatially encoded, resulting in
images of the body. The MRI machine emits an RF (radio frequency) pulse that
specifically binds only to hydrogen.
Like CT, MRI traditionally creates a two dimensional image of a thin "slice" of the
body and is therefore considered a tomographic imaging technique. Modern MRI
instruments are capable of producing images in the form of 3D blocks, which may be
considered a generalisation of the single-slice, tomographic concept.
Figure 2 shows a fMRI scan showing regions of activation in orange, including
the primary visual cortex
Figure 2: A fMRI scan [9]
3. Fiduciary Markers
Fiduciary markers [10] are used in a wide range of medical imaging applications.
Images of the same subject produced with two different imaging systems may be
correlated by placing a fiduciary marker in the area imaged by both systems. In this
case, a marker which is visible in the images produced by both imaging modalities
must be used. By this method, functional information from positron emission
tomography can be related to anatomical information provided by magnetic
resonance imaging (MRI). Similarly, fiducial points established during MRI can be
correlated with brain images generated by magnetoencephalography to localize the
source of brain activity.
Fiducial markers also have other applications for example indoor positioning and
navigation. [11]
Figure 3 shows an example of fiduciary markers taken from reacTIVision.
Figure 3: Fiducial marker example [12]
ReacTIVision is an open source, cross-platform computer vision framework for the
fast and robust tracking of fiducial markers attached onto physical objects, as well as
for multi-touch finger tracking.
4. Photo acoustic imaging
Photo acoustic imaging [13] is a recently developed hybrid biomedical imaging
modality based on the photo acoustic effect. It combines the advantages of optical
absorption contrast with ultrasonic spatial resolution for deep imaging in (optical)
diffusive or quasi-diffusive regime. Recent studies have shown that photo acoustic
imaging can be used in vivo for tumor angiogenesis monitoring, blood oxygenation
mapping, functional brain imaging, and skin melanoma detection, etc.
5. Tomography [14]
Tomography is the method of imaging a single plane, or slice, of an object resulting
in a tomogram. There are several forms of tomography like
 Linear tomography
 Poly tomography
 Zonography
 Orthopantomography
 Computed tomography [15]
X-ray computed tomography, also computed tomography (CT) or computed axial
tomography (CAT), can be used for medical imaging and industrial imaging
methods employing tomography created by computer processing. Digital
geometry processing is used to generate a three-dimensional image of the inside
of an object from a large series of two-dimensional X-ray images taken around a
single axis of rotation.
CT produces a volume of data that can be manipulated, through a process known
as "windowing", in order to demonstrate various bodily structures based on their
ability to block the X-ray beam.
Figure 4 shows computer tomography of human brain, from base of the skull to
top, taken with intravenous contrast medium.
Figure 4: Computed tomography of brain [16]
6. Ultrasound [17]
Medical ultra-sonography uses high frequency broadband sound waves in the mega
Hertz range that are reflected by tissue to varying degrees to produce (up to 3D)
images. Ultrasound is also used as a popular research tool for capturing raw data,
that can be made available through an ultrasound research interface, for the purpose
of tissue characterization and implementation of new image processing techniques.
Creation of three-dimensional images
Recently, techniques have been developed to enable CT, MRI and ultrasound scanning
software to produce 3D images for the physician. Traditionally CT and MRI scans produced
2D static output on film. To produce 3D images, many scans are made, then combined by
computers to produce a 3D model, which can then be manipulated by the physician. 3D
ultrasounds are produced using a somewhat similar technique [18]. In diagnosing disease of
the viscera of abdomen, ultrasound is particularly sensitive on imaging of biliary tract,
urinary tract and female reproductive organs (ovary, fallopian tubes). As for example,
diagnosis of gall stone by dilatation of common bile duct and stone in common bile duct.
With the ability to visualize important structures in great detail, 3D visualization methods are
a valuable resource for the diagnosis and surgical treatment of pathologies. The 3D
equipment was used previously for similar operations with great success. [19]
Other proposed or developed techniques include:





Diffuse optical tomography
Elastography
Electrical impedance tomography
Optoacoustic imaging
Ophthalmology
o A-scan
o
o
o
o
B-scan
Corneal topography
Optical coherence tomography
Scanning laser ophthalmoscopy
Some of these techniques are still at a research stage and not yet used in clinical routines.
Compression of medical images
Medical imaging techniques produce very large amounts of data, especially from CT, MRI
and PET modalities. As a result, storage and communications of electronic image data are
prohibitive without the use of compression. JPEG 2000 is the state-of-the-art image
compression DICOM standard for storage and transmission of medical images. The cost and
feasibility of accessing large image data sets over low or various bandwidths are further
addressed by use of another DICOM standard, called JPIP, to enable efficient streaming of
the JPEG 2000 compressed image data.[1]
1.
JPEG2000
JPEG 2000 is an image compression standard and coding system. It was created by the joint
photographic experts group committee in 2000 with the intention of superseding their
original discrete cosine transform-based JPEG standard (created in 1992) with a newly
designed, wavelet-based method. [20]
The standardized filename extension is .jp2 for ISO/IEC 15444-1 conforming files
and .jpx for the extended part-2 specifications, published as ISO/IEC 15444-2.
The block diagram of JPEG 2000 is shown in figure 5
Figure 5: Block diagram of JPEG 2000[21]
Quantization: Each subband may use a different step-size. Quantization can be skipped to
achieve lossless coding
• Entropy coding: Bit plane coding is used, the most significant bit plane is coded first.
• Quality scalability is achieved by decoding only partial bit planes, starting from the MSB.
Skipping one bit plane while decoding = Increasing quantization stepsize by a factor of 2.
[21]
As seen in figure 6, it is a png image showing comparison of compression techniques for
images.
The first one is uncompressed, 378 kilo bytes. Second one is JPEG JFIF and third one is
JPEG2000 both 11.2 kilo bytes.
Figure 6: Comparison of JPEG2000 with JPEG [23]
2.
JPIP
JPIP (JPEG 2000 Interactive Protocol) [22] is a compression streamlining protocol that
works with JPEG 2000 to produce an image using the least bandwidth required. It can be
very useful for medical and environmental awareness purposes, among others, and many
implementations of it are currently being produced, including the HiRISE camera's
pictures, among others.[24]
JPIP has the capacity to download only the requested part of a picture, saving bandwidth,
computer processing on both ends, and time. It allows for the relatively quick viewing of
a large image in low resolution, as well as a higher resolution part of the same image.
Using JPIP, it is possible to view large images (1Gigapixel) on relatively light weight
hardware.
Non-diagnostic imaging
Neuro-imaging has also been used in experimental circumstances to allow people (especially
disabled persons) to control outside devices, acting as a brain computer interface. [25]
Neuro-imaging falls into two broad categories:


Structural imaging, which deals with the structure of the brain and the diagnosis of gross
(large scale) intracranial disease (such as tumor), and injury, and
functional imaging, which is used to diagnose metabolic diseases and lesions on a finer
scale (such as Alzheimer's disease) and also for neurological and cognitive
psychology research and building brain-computer interfaces.
Functional imaging enables, for example, the processing of information by centers in the
brain to be visualized directly. Such processing causes the involved area of the brain to
increase metabolism and "light up" on the scan. See figure 7, it is a 3D MRI scan of a
semiconscious brain.
Figure 7: 3D MRI section of the head [25]
Proposed Work
This project introduces the concept of medical imaging and divulges into its technologies like
MRI, tomography, ultrasound etc. It will also compare the compression techniques of
medical imaging i.e. JPEG2000 and JPIP on the basis of their bit rates, SSIM index, and
complexity.
This project proposes to demonstrate creation of 3D images of CT/MRI scan from a normal
2D image. It also shows some circumstances of neuroimaging i.e non-diagnostic medical
imaging as in Figure 6.
References
1. http://en.wikipedia.org/wiki/Medical_imaging
2. Mitchell G, Morgan-Hughes G; "Radiation-reduction strategies in cardiac computed
tomographic angiography"; Roobottom CA, November 2010
3. http://www.sciencedaily.com/releases/2009/03/090303125809.html
4. http://books.google.com/books?id=GSd0IqSt3bsC&printsec=frontcover&dq=radiogra
phy&hl=en&sa=X&ei=TLtDT-3DBbr0QH2s_ijBw&ved=0CEsQ6AEwAA#v=onepage&q=radiography&f=false
5. http://en.wikipedia.org/wiki/Medical_radiography
6. Vedantham S, Karellas A ; Medical Scholar, Dept of Radiology -Modelling the
performance characteristics of Computed Radiography (CR) systems; University of
Massachusetts, Worcester, MA, USA
7. http://www.dental-xray-equipment.com/dental-x-ray-equipment/digital-radiography/
8. Squire LF, Novelline RA ; Squire's fundamentals of radiology (5th ed.). Harvard
University Press. ISBN 0-674-83339-2; 1997
9. http://en.wikipedia.org/wiki/Image:FMRI.jpg
10. BJ Erickson and CR Jack Jr.; Correlation of single photon emission CT with MR
image data using fiduciary markers. American Journal of Neuroradiology, Vol 14,
Issue 3 713-720.
11. Mulloni A, Wagner D, Barakonyi I, Schmalsteing D; Graz Univ of TechnologyIndoor positioning and navigation with camera phones; Graz- April 2009
12. http://reactivision.sourceforge.net/
13. M. Xu and L.H. Wang. "Photoacoustic imaging in biomedicine". Review of Scientific
Instruments 77 (4): 041101. doi:10.1063/1.2195024; 2006
14. “Computed tomography—Definition from the Merriam-Webster Online Dictionary"
Retrieved 2009-08-18.
15. Herman, G. T., Fundamentals of computerized tomography: Image reconstruction
from projection, 2nd edition, Springer, 2009
16. http://ehealthmd.com/content/what-ct-scan
17. Richard S. C. Cobbold, Foundations of Biomedical Ultrasound, pp. 422–423. 978-019-516831-0
18. Yamani A, King Fahd Univ of Pet & Miner, Dhahran, Saudi Arabia; A novel pulseecho technique for medical three dimensional imaging; Dec 1997
19. Chris C. Shaw- Dimensions in medical imaging: the more the better? Proceedings of
the IEEE, Vol 98. No.1, January 2012
20. Rao, K.R.; Huh Y; Dept of Elec Eng, Univ of Texas, Arlington, TX; Video/Image
processing and multimedia communications 4th EURASIP-IEEE Region 8
International symposium, JPEG 2000- USA-2002
21. eeweb.poly.edu/~yao/EE3414/JPEG.pdf
22. Khademi A; Krishnan- Dept of Elect and Comp Eng, Ryerson Univ, Toronto,
Ontario; Comparison of JPEG 2000 and other lossless compression schemes; Paper in
Engineering in medicine and biology society, 2005
23. http://en.wikipedia.org/wiki/File:JPEG_JFIF_and_2000_Comparison.png (Figure 5)
24. Microsoft and NASA Bring Mars Down to Earth Through the WorldWide Telescope
(07.12.10) - NASA
25. Filler, AG: The history, development, and impact of computed imaging in
neurological diagnosis and neurosurgery: CT, MRI, DTI: Nature Preceding DOI:
10.1038/npre.2009.3267.5.Neurosurgical Focus (in press); 2009
26. http://en.wikipedia.org/wiki/Neuroimaging (Figure 6)
a. Picture reference: sbharris on wikipedia
27. http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org
%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6030946&authDecision=-203