abstract
New developments are making the technology faster, more powerful, less invasive, and less expensive. While the technology evolves, new devices are developed, in purpose to be used in the hospitals. Many new imaging methods are used in biomedical applications today and can predict the growth of a tumor or detect a disease. The advantages are numerous, but the problems, during the acquisition and use by the staff, are also remarkable.
Introduction
We have come from the family doctor’s signature black bag in the first half of the 20t h century to the powerful scanning equipment of the modern medical center, from tens of thousands dying in influenza epidemics to hundreds of thousands of seniors receiving their annual flu shots, and from an average life expectancy of about 50 years to our present expectancy of 75 years. The biomedical community is taking advantage of the power of computing and technology so as to manage and analyse data. Imaging technologies save day to day more and more people.
X-rays, endoscopes, CT (computed tomography) scans, MRI (magnetic resonance imaging), digital mammography—these imaging technologies make it possible for medical scientists to peer into the body without cutting through the skin. With video monitors and robotic equipment, surgery becomes less invasive and less traumatic to the body (Sawchuck, 2000). Noninvasive means of looking into the human body are now being used to diagnose a wide variety of diseases, including cancer, Alzheimer’s disease, stroke, heart failure, and vascular disease (President’s Committee of Advisors on Science and Technology, 2000). The first imaging technologies, the X-ray (discovered by W. K. Roentgen) and EEG (electroencephalogram), were primitive by today’s standards, but both have been considerably improved and provided the conceptual base of the other amazing imaging technologies that have recently emerged.
The most common, CAT (computer-assisted tomography) scans, combine X-rays with computer technology to create cross-sectional images of the patient’s body, which are then assembled into a three-dimensional picture that displays organs, bones, and tissues in great detail. MRI scanners use magnets and radio waves instead of X-rays to generate images that provide an even better view of soft tissues, such as the brain or spinal cord (President’s Committee of Advisors on Science and Technology, 2000).
Much of today’s imaging technology relies on microprocessors and software. In addition, the great advances in noninvasive sensing, tomography, and imaging technologies now allow repeated studies with minimal stress and damage (National Research Council, & Institute for Laboratory Animal Research, 2002).
Medical imaging is often thought of as a way of viewing anatomical structures of the body. Indeed, X-ray computed tomography and magnetic resonance imaging yield exquisitely detailed images of such structures. It is often useful, however, to acquire images of physiologic function rather than of anatomy. Such images can be acquired by imaging the decay of radioisotopes bound to molecules with known biological properties. This class of imaging techniques is known as nuclear medicine imaging.
Although the mathematical sciences were used in a general way for image processing, they were of little importance in biomedical work until the development in the 1970s of computed tomography for the imaging of X-rays (leading to the CAT scan) and isotope-emission tomography (leading to positron-emission tomography [PET] scans and single-photon-emission computed tomography [SPECT] scans). In the 1980s, MRI eclipsed the other modalities in many ways as the most informative medical imaging methodology (Webb, 1988).
Table 1 summarises some of the imaging methods used in biomedical applications.
Technologies such as those in Table 1 are all being investigated in small-animal models. The goal is to marry fundamental advances in molecular and cell biology with those in biomedical imaging to advance the field of molecular imaging (TA-Datenbank-Nachrichten, 2001). The two basic starting points in evaluating the overall utility of a medical technology are efficacy and safety. If a technology is not efficacious, it should not be used. In addition, efficacy and safety data are needed to evaluate the cost effectiveness of a technology (Banta, Clyde, & Williams, 1981).
Table 1. Imaging methods used in biomedical applications
• X-ray projection imaging (discovered in 1895)
• X-ray CT (1972)
• MRI (1980)
• Magnetic resonance spectroscopy (MRS)
• SPECT
• PET (1974)
• Gamma camera (1958)
• Nuclear magnetic resonance (NMR, 1946)
• Ultrasonics
• Electrical source imaging (ESI)
• Electrical impedance tomography (EIT)
• Magnetic source imaging (MSI)
• Medical optical imaging
• Micro computerised axial tomography (MicroCAT)
• Optical and thermal diagnostic imaging (OCT, DOT)
Biomedical imaging devices have been used to obtain anatomical images and to provide localised biochemical and physiological analysis of tissues and organs. The ability of these devices to provide anatomical images and physiological information has provided unparalleled opportunities for biomedical and clinical research, and has the potential for important improvements in the diagnosis and treatment of a wide range of diseases (National Institute of Biomedical Imaging and Bioengineering [NIBIB], 2002).
Technological devices visualise and enlarge somatic space, rendering images of our most infinitesimal cells, molecules, and genetic structures, which allows for a more precise manipulation of our muscles, tissues, and bones (Sawchuck, 2000). Imaging tests now provide much clearer and more detailed pictures of organs and tissues. New imaging technology allows us to do more than simply view anatomical structures such as bones, organs, and tumours. Functional imaging—the visualisation of physiological, cellular, or molecular processes in living tissues—enables us to observe activity such as blood flow, oxygen consumption, or glucose metabolism in real time.
Imaging technology already has had lifesaving effects on our ability to detect cancer early and more accurately diagnose the disease (especially the PET device). Generally, the purpose of the biomedical imaging techniques is the early detection, clinical diagnosis, and staging of a disease, and therapeutic applications (Biomedicallmaging Symposium: Visualizing the Future of Biology and Medicine, 1999). Imaging technologies have many applications in biomedicine. Oncology, cardiology, and ophthalmology are only some of its sections that use these technologies, which everyday are developed more and more.
PROBLEMS AND DISADVANTAGES OF IMAGING TECHNOLOGIES
Despite all the promises, the use of imaging technologies in biomedicine and bioengineering evoke many problems. All biomedical imaging devices suffer from various limitations that can restrict their general applicability. Some major limitations are sensitivity, spatial resolution, temporal resolution, and the ease of the interpretation of data. One way to circumvent these limitations is to develop technological and methodological approaches that improve and extend the sensitivity and the information content of individual imaging techniques. Another way is to combine two or more complementary biomedical imaging techniques (like MRI and PET, MRI and MEG, and optical MRI).
Table 2 summarises some problems of the imaging technologies.
There is no crystal ball to predict the future of medical imaging technologies. New applications continue to be explored for both diagnosis and treatment (Canadian Institute for Health Information, http://www.cihi.ca). Biomedical imaging has seen truly exciting advances in recent years. New imaging methods can now reflect internal anatomy and dynamic body functions heretofore only derived from textbook pictures, and applications to a wide range of diagnostic and therapeutic procedures can be envisioned. Not only can technological advances create new and better ways to extract information about our bodies, but they also offer the promise of making some existing imaging tools more convenient and economical.
Advances based on medical research promise new and more effective treatments for a wide variety of diseases. New noninvasive imaging techniques for the earlier detection and diagnosis of disease are essential to take full advantage of new treatments and to promote improvements in healthcare. The development of advanced genetic and molecular imaging techniques is necessary to continue the rapid pace of discovery in molecular biology.
Table 2. Problems and disadvantages of imaging technologies
• The high cost of equipment and their maintenance, which aggravates the national economy for medicine
• Wasteful expenditures because of bad usage by users and technical staff (20 to 40%)
• The technology changes rapidly and devices may become out of date
• Users need education to learn how to break the new technologies in
• Physicians and the nursing staff must continuously be acquainted through articles related to the new technologies and equipment
• New technologies cause disruption and disappointment for staff
• They are venturous for patients because the levels of radiation they are exposed to may be too high
Key paradigms of emerging imaging technologies from different technological areas will be presented, and the engineering principles and research findings leading to the design of efficient bioimaging technologies will be introduced and analysed. Specifically, imaging technologies from space or aerospace research have been identified and successfully applied toward the development of novel high-resolution, multisensor medical imaging systems, with potential applications in digital radiography and CT. Similarly, experimental research findings for defence applications have been applied toward the development of multifusion optical sensing imaging systems and techniques for efficient disease detection (Giakos, 2003).
Today, as for all products and services in all sectors, there exists the DICOM (Digital Imaging and Communications in Medicine) Standards Committee. Its purpose is to create and maintain international standards that help the allocation of medical pictures (like radial tomographies, magnetic tomographies, etc.), and the communication of biomedical diagnostic and therapeutic information in disciplines that use digital images and associated data (DICOM, 2004). DICOM is used or will be used by every medical profession that utilises images within the healthcare industry.
conclusion
The rapid progress in imaging technologies during the last decades has stimulated many developments and applications in medicine, biology, industry, aerospace, remote sensing, meteorology, oceanography, and the environment.
New developments are continually making the technology faster, more powerful, less invasive, and less expensive. Imaging technology was primarily used in medical diagnosis initially, but it is being increasingly used in pure neuroscience, psychological research, and many other fields. The quantitative nature of data will be relevant for the effective diagnosis as well as therapeutic management of patients, whichever disease they have (“Nuclear Medicine Sextet,” 1999).
KEY TERMS
Assessment of Imaging Technology: Research on and development of methods for the evaluation and comparison of new and existing imaging technologies to establish their effectiveness, robustness, and range of applicability.
Bioengineering: The application of engineering principles to the fields of biology and medicine, as in the development of aids or replacements for defective or missing body organs. It is also called biomedical engineering.
Biomedicine: A branch of medical science concerned especially with the capacity of human beings to survive and function in abnormally stressful environments and with the protective modification of such environments. Broadly, it is medicine based on the application of the principles of the natural sciences, especially biology and biochemistry.
Development of Imaging Devices: Research and development of generic biomedical imaging technologies before specific applications are demonstrated.
Diagnostic Imaging: A study section reviews applications dealing with the development and evaluation of new technology for imaging, including instrumentation and software for producing, evaluating, storing, and transmitting images for anatomical, physiological, metabolic, diagnostic, and therapeutic information.
Image Exploitation: Development, design, and implementation of algorithms for image processing and information analysis, including advanced methods for the acquisition, storage, and display of images; research and development on image-guided procedures; and techniques for using multidimensional images to understand physiology and normal and abnormal function.
Medical Device: Any instrument, apparatus, appliance, material, or other article, whether used alone or in combination, including the software necessary for its proper application, intended for the purpose of the diagnosis, prevention, monitoring, treatment, alleviation, or investigation of a disease, injury, or handicap.
Medical Imaging: Term describing the various technologies that produce pictures or images of the body and its structures. Imaging technologies include X-ray, CT scanning, PET scanning, and ultrasound. This term also includes technology such as digital cameras, which produce digital images.
Medical Imaging Technologies: A study section reviews all modalities of medical imaging, including gamma ray; MRI; functional MRI; PET; SPECT; X-ray; CT; visible, infrared, and ultraviolet photons; and optical, photo-acoustic, microwave-acoustic, and exotic imaging methods.
Minimally Invasive Technologies: Basic research involving the use of robotics technologies for actuation, sensing, control, programming, and the human-machine interface, and the design of mechanisms to determine research end points such as diagnosis and the automated or remote treatment of disease.
