Medical imaging
Medical imaging encompasses a range of techniques utilized in medicine to visualize the human body for diagnostic and therapeutic purposes. The discipline integrates both basic and advanced technology to produce images of the internal structures of the body, aiding in the diagnosis and management of diseases. Core techniques within this domain include X-rays, ultrasound, CT scan, and MRI scan, among others.
History[edit | edit source]
Medical imaging's inception can be traced back to the discovery of X-rays by Wilhelm Conrad Roentgen in 1895. Over the subsequent century, advancements in technology and a deeper understanding of human physiology have led to the development of a multitude of imaging modalities, each serving unique diagnostic purposes.
Modalities[edit | edit source]
Medical imaging is categorized based on the technology and physical principles employed:
X-rays[edit | edit source]
Utilizes ionizing radiation to produce images of the body's internal structures. Commonly used for visualizing bones, detecting fractures, and monitoring lung conditions.
Ultrasound[edit | edit source]
Employs high-frequency sound waves to produce images of organs and tissues. Often used in obstetrics to monitor fetal development, as well as for visualizing the heart, blood vessels, and abdominal organs.
CT Scan (Computed Tomography)[edit | edit source]
Combines multiple X-ray images taken from different angles to produce cross-sectional images or "slices" of the body. Common applications include head scans, chest scans, and abdominal scans.
MRI Scan (Magnetic Resonance Imaging)[edit | edit source]
Uses strong magnets and radio waves to produce detailed images of the body's internal structures. Preferred for brain imaging, joint evaluations, and certain types of cancer detection.
Advantages and Limitations[edit | edit source]
Each imaging modality has its strengths and limitations based on the principles they operate on: X-rays and CT scans use ionizing radiation, which, in excessive amounts, may present health risks. Ultrasound is non-invasive and doesn't use radiation, but its image quality is often inferior to CT and MRI. MRI offers exceptional detail but can be expensive and is not suitable for patients with certain metal implants.
Future Developments[edit | edit source]
Ongoing research aims to enhance the resolution of images, decrease potential risks, and explore novel imaging techniques that can provide more information at the cellular or molecular level.
Glossary of medical imaging[edit | edit source]
An imaging technique that shoots short pulses of ultrasound at targeted tissues and then monitors the tissue response in the form of shear waves that can be measured, and displayed as elastography images. These measurements and images can be used to diagnose or monitor the possible presence of diseased or cancerous tissue, based on the measured stiffness properties of tissues such as breast or liver where areas of increased stiffness may indicate the presence of tumors, fibrosis, scar tissue, and other types of disease or damage.
A diagnostic X-ray imaging procedure used to see how blood flows through the blood vessels and organs of the body. This is done by injecting special dyes, known as contrast agents, into the blood vessel and using x-ray techniques such as fluoroscopy to monitor blood flow. Examples include coronary angiography (heart), cerebral angiography (brain), and peripheral angiography (hands, arms, feet and legs).
B[edit | edit source]
A measure of how a biomaterial interacts in the body with the surrounding cells, tissues and other factors. Abiomaterial is considered to have good biocompatibility if it does not generate a vigorous immune response, resists build-up of proteins and other substances on its surface that would hinder its function, and is resistant to infection.
The application of concepts and methods of engineering, biology, medicine, physiology, physics, materials science, chemistry, mathematics and computer sciences to develop methods and technologies to solve health problems in humans.
The branch of biology that is concerned with the acquisition, storage, display and analysis of biological information. Analysis of biological information includes statistical and computational methods to model biological processes.
Any matter, surface, or construct that interacts with biological systems. Biomaterials can be derived from nature or synthesized in the laboratory using metallic components, polymers , ceramics, or composite materials. Medical devices made of biomaterials are often used to replace or augment a natural function. Examples include heart valves, hip replacements, and materials used regularly in dentistry and surgery.
The science and the branch of medicine concerned with the development and use of imaging devices and techniques to obtain internal anatomic images and to provide biochemical and physiological analysis of tissues and organs.
Using biological form and function seen in nature to inspire the design of solutions to engineering problems.
A manufactured or engineered device that provides an environment that supports biological processes. Many bioreactors are used to grow cells or tissues for use in tissue engineering.
A device that uses biological material, such as DNA, enzymes and antibodies, to detect specific biological, chemical, or physical processes and then transmits or reports this data.
A highly selective, semi-impermeable boundary that divides the brain from the rest of the body. It allows the passage of vital molecules through specialized transport proteins and diffusion mechanisms.
A form of radiation therapy in which one or more small radioactive sources is placed in or adjacent to an arearequiring treatment. The dose rate and longevity of the radiation source is chosen to reflect the treatment plan and whether the radioactive material is left in place temporarily or permanently. A key feature of brachytherapy is that the radiation affects only a very localized area around the radiation source. Brachytherapy is commonly used to treat prostate, cervical and breast cancers.
A system that uses the brain’s electrical signals to allow individuals with limited mobility to learn to use theirthoughts to move a computer cursor or other devices like a robotic arm or a wheelchair.
C[edit | edit source]
Changing the function of a cell using chemical, protein or even mechanical force. Most commonly, a cell, like a skin cell, may be treated with protein factors that reprogram it to become a stem cell that can then be reprogrammed, with various protein or chemical factors, to function as a different type of cell such as a liver, heart or nerve cell.
The amount of a chemical changes over a specified distance, generally increasing from a lower to higher amount. The gradual increase in the amount of a chemical drives many processes in our body that allow cell growth.
An interactive software-based system designed to assist physicians and other health professionals as well as patients with diagnostic and treatment decisions and reminders. The system compiles and analyzes medical information from raw data, health observations, and other medical information sources.
The use of mathematics, statistics, physics and computer science to study the mechanism and behavior of complex systems by computer simulation. A computational model contains numerous variables that characterize the system being studied. Simulation is done by adjusting these variables and observing how the changes affect the outcomes predicted by the model.
A computerized X-ray imaging procedure in which a narrow beam of X-rays is aimed at a patient and quickly rotated around the body, producing signals that are processed by the machine’s computer to generate cross-sectional images—or “slices”—of the body. These slices are called tomographic images and contain more detailed information about the internal organs than conventional X-rays.
A substance used to enhance the imaged appearance of structures, processes or fluids within the body in biomedical imaging.
D[edit | edit source]
A neurosurgical treatment utilizing a neurostimulator placed in the brain to deliver electrical signals to specificparts of the brain to help control unwanted movements such as in Parkinson’s disease or regulate the firing of neurons in the brain to help control the symptoms of disorders such as epilepsy or depression.
Engineered technologies for the targeted delivery and/or controlled release of therapeutic agents.
E[edit | edit source]
A medical imaging technique that measures the elasticity or stiffness of a tissue. The technique captures snapshots of shear waves, a special type of sound wave, as they move through the tissue. The stiffness of the tissue gives information about the possible presence of disease. For example tumors are harder than the surrounding normal tissue and disease livers are stiffer than healthy ones.
The recording of electrical activity along the scalp resulting from current flowing within the neurons of the brain.EEG can be used to diagnose epilepsy and other disorders associated with altered brain electrical activity.
A kind of radiation including visible light, radio waves, gamma rays, and x-rays, in which electric and magnetic fields vary simultaneously. The different forms are differentiated by their wavelength and energy. For instance, visible light has relatively long wavelengths and less energy compared to x-rays or gamma rays with short wavelengths and high energy.
Application of an external electrical field to increase the permeability of the cell membrane. It is usually used inmolecular biology as a way of introducing some substance into a cell such as a drug, protein, or piece of DNA that can change the cell’s function.
A thin illuminated flexible or rigid tube-like optical system used to examine the interior of a hollow organ or bodycavity by direct insertion. Instruments can be attached for biopsy and surgery. Similar technology is used in a laparoscope.
The external skeleton that supports and protects an animal’s body in contrast to the bones of an internal skeleton. Rehabilitation engineers have used this design in nature to develop exoskeletons that attach to the outside of the body and assist individuals with functions like arm and leg movement.
The ECM is a collection of extracellular molecules secreted by support cells that provides structural and biochemical support to the surrounding cells.
Extracellular vesicles (EVs) are nanosized, membrane-bound vesicles released from cells that can transport cargo-- including DNA, RNA, and proteins--between cells as a form of intercellular communication. For example, EVs released from healthy cells can carry DNA, RNA or proteins that help to direct repair of damaged tissues. EVs released from tumor cells can carry DNA, RNA, and proteins that act to help the tumor to metastasize to other tissues.
F[edit | edit source]
The emission of light by a substance that has absorbed light or other electromagnetic radiation. The absorbed and emitted light are usually different wavelengths and therefore produce different colors.
A fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores are usually bonded to a molecule serving as a marker to stain tissues, cells, or materials in methods including fluorescent imaging and spectroscopy.
A non-invasive therapeutic technique that directs ultrasonic waves to a specific location.
A non-invasive technology that uses high-frequency sound waves and microbubbles to reversibly open the blood-brain barrier. The ultrasound waves are emitted from a device called a transducer.
An MRI-based technique for measuring brain activity. It works by detecting the changes in blood oxygenation and flow that occur in response to neural activity – when a brain area is more active it consumes more oxygen and to meet this increased demand blood flow increases to the active area. fMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process.
G[edit | edit source]
Electromagnetic radiation of the shortest wavelength and the highest energy.
GAGs are a main component of the ECM and are linked to the fibrous proteins in the ECM which include collagen, elastin, fibronectin, and laminin.
H[edit | edit source]
A technology that provides the sense of touch to the user through forces, vibrations or motions. For medical procedures, haptic interfaces can improve minimally-invasive surgery by relaying the sense of pressure and touch through the instruments used by the surgeon. Haptic technology has been introduced into the design of prosthetics to provide sensory feedback to the user.
A biomaterial made up of a network of polymer chains that are highly absorbent and as flexible as natural tissue.Hydrogels have a number of uses including as scaffolds for tissue engineering, as sustained release drug delivery systems, and as biosensors that are sensitive to specific molecules such as glucose.
I[edit | edit source]
Medical procedures, primarily minimally invasive surgery, performed through a small incision or natural orifice using robotic tools operated remotely by a surgeon with visualization by devices such as cameras small enough to fit into a minimal incision.
A biological staining technique in which the fluorescent signaling molecule is bound to an antibody to a protein of interest. When the “fluorescently tagged” antibody binds to its target protein the site or distribution of that protein can be visualized with the appropriate imaging devices.
Man-made medical devices implanted in the body to replace or augment biological functions. Such devices range from those that provide structural support, such as a hip replacement to those that contain electronics, such as pacemakers. Some implants are bioactive such as a drug-eluting stent used to open a blocked artery.
A laboratory experiment or process performed in a test tube, culture dish, or elsewhere outside a living animal.
A stem cell that is formed by the introduction of stem-cell inducing factors into a differentiated cell of the body,typically a skin cell.
A type of electromagnetic radiation that can strip electrons from an atom or molecule – a process called ionization. Ionizing radiation has a relatively short wavelength on the electromagnetic spectrum. Examples of ionizing radiation include gamma rays, and X-rays. Lower energy ultraviolet, visible light, infrared, microwaves, and radio waves are considered non-ionizing radiation.
L[edit | edit source]
A thin, lighted telescope-like viewing instrument that is inserted through a small incision or natural orifice toexamine and operate on abdominal and pelvic structures. Similar technology is used in an endoscope. “Laparo” is derived from the Greek root for abdomen and pelvis; however devices similar to laparoscopes are used for other parts of the body such as thoroscopes for chest surgery.
A technique used to measure the total local microcirculatory blood perfusion including the perfusion in capillaries, arterioles, venules and shunting vessels. The technique is based on the emission of a scanning beam of laser light and the Doppler shift that occurs when light particles hit moving blood cells.
M[edit | edit source]
A special MRI technique to capture snapshots of shear waves that move through the tissue and create “elastograms” or images that show tissue stiffness. MRE is used to non-invasively detect hardening of the liver caused by chronic liver disease. MRE also has the potential to diagnose diseases in other parts of the body.
A non-invasive imaging technology used to investigate anatomy and function of the body in both health and disease without the use of damaging ionizing radiation. It is often used for disease detection, diagnosis, and treatment monitoring. It is based on sophisticated technology that excites and detects changes in protons found in the water that makes up living tissues.
A non-invasive analytic imaging technique used to study metabolic changes in diseases affecting the brain, including tumors, strokes, and seizures. The technique is also used to study the metabolism of other organs. MRS complements MRI as a non-invasive means for the characterization of tissue, by providing measure of the concentration of different chemical components within the tissue.
An X-ray imaging method used to image the breast for the early detection of cancer and other breast diseases. It is used as both a diagnostic and screening tool.
A term used to define non-blood adult stem cells from a variety of tissues. However, it is not clear whethermesenchymal stem cells from different tissues are the same.
An abbreviation for mobile health, which is the practice of medicine and public health supported with mobile devices such as mobile phones for health services and information.
Microscopic, preformed bubbles composed of varying materials that enable widespread applications. One application of microbubbles in medicine is as a contrast agent to help obtain clearer ultrasound images.
A multidisciplinary field including engineering, physics, chemistry and biotechnology involving the design of systems for the precise control and manipulation of fluids on a small, sub-millimeter scale. Typically fluids are moved, mixed, separated or processed in various ways.
Particles between 0.1 and 100 m in size. A m is a micrometer, which is one-millionth of a meter. Man-mademicroparticles include ceramics, glass, polymers and metals. In biological systems, microparticles are small membrane- bound vesicles derived from cells circulating in the bloodstream. Microparticles are generally 1000 times larger than nanoparticles.
Using microscopes to view samples and objects that cannot be seen with the unaided eye.
A surgical procedure typically utilizing one or more small incisions through which laparoscopic surgical tools areinserted and manipulated by a surgeon. Minimally invasive surgery can reduce damage to surrounding healthy tissue, decrease the need for pain medication, and reduce patient recovery time.
A discipline that involves the visualization of molecular processes and cellular functions in living organisms. Withthe inclusion of a biomarker, which interacts chemically with tissues and structures of interest, many imaging techniques can be used for molecular imaging including ultrasound, x-rays, magnetic resonance imaging, optical imaging, positron emission tomography, and single photon emission computed tomography.
The measurement of the form of living systems or their parts. In medicine, morphometry is often used to study changes in brain structure during development, aging and in response to disease. Researchers can measure anatomical features of the brain in terms of shape, mass and volume and derive various measures such as grey matter density and white matter connectivity using neuroimaging techniques and neuroinformatics.
An imaging technique that uses two or three-photon excitation of a fluorophore in a specimen. Fluorescence occurs when two or more photons of excitation light are absorbed by the specimen at the same time. Because excitation occurs only where photons coincide, there is reduced phototoxicity and photobleaching and greater depth penetration. Because of the reduced toxicity, the method is ideal for imaging living specimens especially when deep imaging is required.
Multiscale modeling uses mathematics and computation to quantitatively represent and simulate a system at more than one scale while functionally linking the mathematical models across these scales. Biological and behavioral scales include atomic, molecular, molecular complexes, sub-cellular, cellular, multi-cell systems, tissue, organ, multi-organ systems, organism/individual, group, organization, market, environment, and populations.
N[edit | edit source]
Ultrafine particles between 1 and 100 nanometers in size. The size is similar to that of most biological molecules and structures. Nanoparticles can be engineered for a wide variety of biomedical uses including diagnostic devices, contrast agents, physical therapy applications, and drug delivery vehicles. A nanoparticle is approximately 1/10,000 the width of a human hair. Nanoparticles are generally 1000 times smaller than microparticles.
The manipulation of matter with at least one dimension sized from 1 to 100 nanometers. Research areas include surface science, molecular biology, semiconductor physics, and microfabrication. Applications are diverse and include device physics, molecular self-assembly, and precisely manipulating atoms and molecules.
A spectroscopic method that uses the near-infrared region of the electromagnetic spectrum for pharmaceutical and medical diagnostics, typically measurements of blood sugar and blood oxygen levels.
Includes the use of a number of techniques to image the structure and function of the brain, spinal cord, and associated structures.
A broad discipline of neuroscience and biomedical engineering concerned with developing devices that can substitute a motor, sensory or cognitive function lost due to injury or disease. Examples encompass a wide range including cochlear implants, visual prosthetics, and brain-computer interfaces for conscious control of movement in paralyzed individuals.
A medical specialty that uses radioactive tracers (radiopharmaceuticals) to assess bodily functions and to diagnose and treat disease. Diagnostic nuclear medicine relies heavily on imaging techniques that measure cellular function and physiology.
O[edit | edit source]
A protein encoded by an oncogene which can cause the transformation of a cell into a tumor cell if introduced into it.
A technique for obtaining sub-surface images such as diseased tissue just below the skin. For example, ophthalmologists use OCT to obtain detailed images from within the retina. Cardiologists also use it to help diagnose coronary artery disease.
A technique for non-invasively looking inside the body, as is done with x-rays. Unlike x-rays, which use ionizingradiation, optical imaging uses visible light and the special properties of photons to obtain detailed images of organs and tissues as well as smaller structures including cells and molecules.
P[edit | edit source]
The movement of fluid through blood vessels to a cell tissue or an organ, generally referring to blood.
A particle of light or electromagnetic radiation. The energies of photons range from high-energy gamma rays and x-rays to low-energy radio waves.
Crystals in the transducer of an ultrasound device that vibrate when an electric signal is applied, emitting high-frequency sound pressure waves. The crystals are the crucial component of an ultrasound device both producing and detecting the ultrasound waves used to image structures inside of the body.
Testing and treating of patients at sites close to where they live. Rapid diagnostic tests are used to obtain immediate, on-site results. The success of the concept relies on portable, rapid diagnostic devices that provide results directly to the user, which allows health care workers in remote areas to test and treat patients at the time of the visit.
A large molecule composed of many repeating subunits. Polymers range from familiar synthetic plastics such aspolystyrene to natural biopolymers such as DNA. Polymers have unique physical properties, including strength, flexibility and elasticity.
PET scans use radiopharmaceuticals to create 3 dimensional images. The decay of the radiotracers used with PET scans produce small particles called positrons. When positrons react with electrons in the body they annihilate each other. This annihilation produces two photons that shoot off in opposite directions. The detectors in the PET scanner measure these photons and use this information to create images of internal organs.
Progenitor cells are cells that are similar to stem cells but instead of the ability to become any type of cell, theyare already predisposed to develop into a particular type of cell.
The design, fabrication, and fitting of artificial body parts.
R[edit | edit source]
The emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.
Radioactive tracers are made up of carrier molecules that are bonded tightly to a radioactive atom. The carriermolecule is designed to bind to the tissue being examined so that the radioactive atom can be scanned to produce an image from inside the body.
This technique relies on inelastic scattering of visible, near-infrared, or near-ultraviolet light that is delivered by a laser. The laser light interacts with molecular vibrations in the material being examined, and shifts in energy are measured that reveal information about the properties of the material. The technique has a wide variety of applications including identifying chemical compounds and characterizing the structure of materials and crystals. In medicine, Raman gas analyzers are used to monitor anesthetic gas mixtures during surgery.
A broad field that includes tissue engineering but also incorporates research on self-healing – where the body uses its own systems, sometimes with the help of foreign biological material to rebuild tissues and organs.
The use of engineering science and principles to develop technological solutions and devices to assist individuals with disabilities, and aid the recovery of physical and cognitive functions lost because of disease or injury.
Surgery performed through very small incisions or natural orifices using thin finger-like robotic tools controlledremotely by the surgeon through a telemanipulator or computer interface.
S[edit | edit source]
A structure of artificial or natural materials on which tissue is grown to mimic a biological process outside the body or to replace a disease or damaged tissue inside the body.
In medicine and biotechnology, sensors are tools that detect specific biological, chemical, or physical processes and then transmit or report this data. Some sensors work outside the body while others are designed to be implanted within the body. Sensors help health care providers and patients monitor health conditions. Sensors are also used to monitor the safety of medicines, foods and other environmental substances we may encounter.
A nuclear medicine imaging technique using gamma rays. SPECT imaging instruments provide 3 dimensional images of the distribution of radioactive tracer molecules that have been introduced into the patient’s body. The 3D images are computer generated from a large number of images of the body recorded at different angles by cameras that rotate around the patient.
the branch of science concerned with the investigation and measurement of spectra produced when matter interacts with or emits electromagnetic radiation.
An undifferentiated cell of a multicellular organism that is capable of giving rise to more of the same cell typeindefinitely, and has the ability to differentiate into many other types of cells that form the structures of the body.
The study of the structure of large biomolecules like proteins and nucleic acids, how the structure relates to thefunction of the molecule, and how alterations in structure affect function. Various methods such as crystallography are used to gain information about the structure of a molecule. This information is often analyzed with bioinformatics techniques to obtain or solve the structure of the molecule.
A form of super high resolution microscopy designed to capture extremely clear images of cells and molecules, even when they are moving quickly. The sophisticated technique uses a number of filters and other light processors to rapidly scan images, combine multiple images, and eliminate out of focus light in order to obtain super-resolution images of cells and subcellular structures in motion.
A large circular facility/device that accelerates sub-atomic particles in a magnetic field in a circular path thatgenerates electromagnetic radiation with a defined exit (beam line). One type of synchrotron (a synchrotron light source) converts a high-energy beam of electrons into high-energy x-rays that can be used in a number of applications including biomedical imaging.
T[edit | edit source]
The use of communications technologies to provide and support health care at a distance.
An international unit to describe the strength of a magnetic field.
The relatively experimental science of combining therapy and diagnosis into a single procedure or molecule. Towards this end, bioengineers are building multi-functional nanoparticles that can be introduced into a patient, find the site of disease, diagnose the condition, and deliver the appropriate, personalized therapy.
An interdisciplinary and multidisciplinary field that aims at the development of biological substitutes that restore, maintain, or improve tissue function.
U[edit | edit source]
A form of acoustic energy, or sound, that has a frequency that is higher than the level of human hearing. As a medical diagnostic technique, high frequency sound waves are used to provide real-time medical imaging image inside the body without exposure to ionizing radiation. As a therapeutic technique, high frequency sound waves interact with tissues to destroy diseased tissue such as tumors, or to modify tissues, or target drugs to specific locations in the body.
X[edit | edit source]
A form of high energy electromagnetic radiation that can pass through most objects, including the body. X-rays travel through the body and strike an x-ray detector (such as radiographic film, or a digital x-ray detector) on the other side of the patient, forming an image that represents the “shadows” of objects inside the body.
See Also[edit | edit source]
| X-ray/ Radiography | |||||||||||||
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| MRI | |||||||||||||
| Ultrasound | |||||||||||||
| Radionuclide |
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| Optical/Laser | |||||||||||||
| Thermography | |||||||||||||
| Target conditions | |||||||||||||
| Medical imaging Resources | |
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