That is usually the journal article where the information was first stated. In most cases Physiopedia articles are a secondary source and so should not be used as references. Physiopedia articles are best used to find the original sources of information see the references list at the bottom of the article. If you believe that this Physiopedia article is the primary source for the information you are refering to, you can use the button below to access a related citation statement.
How do MRIs detect medical problems?
Medical imaging is often perceived to designate the set of techniques that noninvasively produce images of the internal aspect of the body. It is the techniques and processes used to create images of the human body for clinical purposes such as seeking to reveal, diagnose or examine injury, dysfunction or pathology. As a discipline and in its widest sense incorporates radiology, tomography, endoscopy, thermography, medical photography and microscopy e. In the clinical context, medical imaging is generally equated to radiology and the medical practitioner responsible for interpreting and sometimes acquiring the images is a radiologist.
The radiographer or radiologic technologist is usually responsible for acquiring medical images of diagnostic quality, although some radiological interventions are performed by radiologists. Radiography is the use of ionizing electromagnetic radiation such as X-rays to view objects.
This imaging modality utilizes a wide beam of x rays for image acquisition and is the first imaging technique available in modern medicine. Various forms of radiographic images are in use in medical imaging. 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 to provide moving projection radiographs of lower quality.
Contrast media, such as barium, iodine, and air are used to visualize internal organs as they work. Fluoroscopy is also used in image-guided procedures when constant feedback during a procedure is required such as intraoperative and catheter guidance.
The Eclectic History of Medical Imaging | Imaging Technology News
Angiography is the use of fluoroscopy to view the cardiovascular system. An iodine-based contrast is injected into the bloodstream and watched as it travels around. Since liquid blood and the vessels are not very dense, a contrast with high density like the large iodine atoms is used to view the vessels under X-ray.
Angiography is used to find aneurysms, leaks, blockages thromboses , new vessel growth, and placement of catheters and stents. Balloon angioplasty is often done with angiography. Fluoroscopy can be used to examine the digestive system using a substance which is opaque to X-rays, usually barium sulfate or gastrografin , which is introduced into the digestive system either by swallowing or as an enema.
This is normally as part of a double contrast technique, using positive and negative contrast. Barium sulfate coats the walls of the digestive tract positive contrast , which allows the shape of the digestive tract to be outlined as white or clear on an X-ray. Air may then be introduced negative contrast , which looks black on the film. Projectional Radiography , 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.
With the use of radio-opaque contrast media, such as barium, they can also be used to visualize the structure of the stomach and intestines. Dual energy X-ray absorptiometry or DEXA, or bone densitometry is used primarily for osteoporosis tests. It is not projection radiography, as the X-rays are emitted in 2 narrow beams that are scanned across the patient, 90 degrees from each other.
Usually the hip head of the femur , lower back lumbar spine or heel calcaneum are imaged, and the bone density amount of calcium is determined and given a number a T-score.
It is not used for bone imaging, as the image quality is not good enough to make an accurate diagnostic image for fractures, inflammation etc. It can also be used to measure total body fat, though this isn't common. The radiation dose received from DEXA scans is very low, much lower than projection radiography examinations. Computed Tomography CT or CT scan previously known as CAT scan, the "A" standing for "axial" uses a high amount of ionizing radiation in the form of X-rays in conjunction with a computer to create images of both soft and hard tissues.
It is a helical tomography which traditionally produces a 2D image of the structures in a thin section of the body. These images look as though the patient was sliced like bread thus, "tomography"-- "tomo" means "slice". It has a greater ionizing radiation dose burden than projection radiography; repeated scans must be limited to avoid health effects. Contrast agents are often used, depending on the tissues needing to be seen.
Expertise. Insights. Illumination.
Magnetic resonance imaging employs a scanner that 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. MRI uses three electromagnetic fields: a very strong on the order of units of teslas static magnetic field to polarize the hydrogen nuclei, called the static field; a weaker time-varying on the order of 1 kHz field s for spatial encoding, called the gradient field s ; and a weak radio-frequency RF field for manipulation of the hydrogen nuclei to produce measurable signals, collected through an RF antenna.
Like CT, MRI traditionally creates a two dimensional image of a thin "slice" of the body and is therefore considered a tomographic imaging technique. Kagan also kept the distinctive flagpole. He gutted the building, filling in the windows to protect from flooding during hurricanes.
He gave numerous talks for fellow physicians to drum up referrals for spine and brain scans.
Doctors would send him cases only when they were completely stumped. For three years the business was unprofitable. In Kagan was putting scanners on foot-long tractor trailers that moved from hospital to hospital. Since then he has sold them all off, keeping only the building he bought from Kroc. All along, critics have said MRI was too expensive.
Outpatient MRI was once seen as part of the problem. GE lobbied unsuccessfully to have Medicare rate cuts reversed and began to sell some machines close to cost to keep its customers. More recently, outpatient MRI has been seen as part of the solution. Entrepreneurs like Kagan have had their margins squeezed. They now charge far less than large hospital systems for the same scans.
To radiologists, this decrease in cost is coming out of their pockets. Ellie Kincaid covered medicine and health care at Forbes from September to April She previously wrote about scientific research and healthcare providers who d