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During the last 150 years, thousands of papers focusing on the effects or side effects of magnetic or radiofrequency fields have been published. They can be categorized as incidental and physiological. [2] Contraindications to MRI include most cochlear implants and cardiac pacemakers, shrapnel and metallic foreign bodies in the eyes.
MRI contrast agents may be administered by injection into the blood stream or orally, depending on the subject of interest. Oral administration is well suited to gastrointestinal tract scans, while intravascular administration proves more useful for most other scans. MRI contrast agents can be classified [2] by their: Chemical composition
Magnetic resonance myelography (MR myelography or MRI myelography) is a noninvasive medical imaging technique that can provide anatomic information about the subarachnoid space. It is a type of MRI examination that uses a contrast medium and magnetic resonance imaging scanner to detect pathology of the spinal cord , including the location of a ...
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. [1] Contrast agents absorb or alter external electromagnetism or ultrasound , which is different from radiopharmaceuticals , which emit radiation themselves.
Iodinated contrast contains iodine.It is the main type of radiocontrast used for intravenous administration.Iodine has a particular advantage as a contrast agent for radiography because its innermost electron ("k-shell") binding energy is 33.2 keV, similar to the average energy of x-rays used in diagnostic radiography.
Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate them for stenosis (abnormal narrowing), occlusions, aneurysms (vessel wall dilatations, at risk of rupture) or other abnormalities.
Diatrizoate, also known as amidotrizoate, Gastrografin, is a contrast agent used during X-ray imaging. [1] This includes visualizing veins, the urinary system, spleen, and joints, as well as computer tomography (CT scan). [1] It is given by mouth, injection into a vein, injection into the bladder, through a nasogastric tube, or rectally. [2] [3]
However, greater capital costs and effects of off-resonance artefact on image quality mean that many studies are routinely performed at 1.5T. [29] Imaging at 7T field strength is a growing area of research, but is not widely available. [30] Current manufacturers of cardiac-capable MRI scanners include Philips, Siemens, Hitachi, Toshiba, GE.