Search results
Results from the WOW.Com Content Network
A contrast agent usually shortens, but in some instances increases, the value of T1 of nearby water protons thereby altering the contrast in the image. Most clinically used MRI contrast agents work by shortening the T1 relaxation time of protons inside tissues via interactions with the nearby contrast agent.
Cardiac MRI does not pose any specific risks compared to other indications for imaging. [11] Gadolinium based contrast medium is frequently used in CMR and has been associated with nephrogenic systemic fibrosis, predominantly using linear compounds in patients with renal disease.
Nowadays, MRI has all but replaced myelography. [4] MRI is preferable because injection of contrast medium into the spinal canal is infrequently needed for better images. However, a CT myelogram may be useful for patients who cannot undergo MRI (e.g., those with pacemakers or cochlear implants). CT is preferred when MRI images are limited by ...
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.
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.
A physician may recommend cardiac imaging to support a diagnosis of a heart condition. Medical specialty professional organizations discourage the use of routine cardiac imaging during pre-operative assessment for patients about to undergo low or mid-risk non-cardiac surgery because the procedure carries risks and is unlikely to result in the change of a patient's management. [1]
Gadopentetic acid, sold under the brand name Magnevist, is a gadolinium-based MRI contrast agent. [2]It is usually administered as a salt of a complex of gadolinium with DTPA (diethylenetriaminepentacetate) with the chemical formula A 2 [Gd(DTPA)(H 2 O)]; when cation A is the protonated form of the amino sugar meglumine the salt goes under the name "gadopentetate dimeglumine".
When water is in an environment where it can freely tumble, relaxation tends to take longer. In certain clinical situations, this can generate contrast between an area of pathology and the surrounding healthy tissue. To sensitize MRI images to diffusion, the magnetic field strength (B1) is varied linearly by a pulsed field gradient.