magnetic resonance imaging

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magnetic resonance imaging

(MRI), noninvasive diagnostic technique that uses nuclear magnetic resonancemagnetic resonance,
in physics and chemistry, phenomenon produced by simultaneously applying a steady magnetic field and electromagnetic radiation (usually radio waves) to a sample of atoms and then adjusting the frequency of the radiation and the strength of the magnetic field
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 to produce cross-sectional images of organs and other internal body structures. The patient lies inside a large, hollow cylinder containing a strong electromagnet, which causes the nuclei of certain atoms in the body (especially those of hydrogen) to align magnetically. The patient is then subjected to radio waves, which cause the aligned nuclei to "flip"; when the radio waves are withdrawn the nuclei return to their original positions, emitting radio waves that are then detected by a receiver and translated into a two-dimensional picture by computer. Unhampered by bone and capable of producing images in a variety of planes, MRI is used in the diagnosis of brain tumors and disorders, spinal disorders, multiple sclerosis, and cardiovascular disease. The procedure is considered to be without risk, but the scanner may interfere with pacemakers, hearing aids, or other mechanical devices. Although the images are similar in many ways to those of CAT scansCAT scan
[computerized axial tomography], X-ray technique that allows relatively safe, painless, and rapid diagnosis in previously inaccessible areas of the body; also called CT scan.
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, they are obtained without X rays or other radiation, and generally provide more contrast between normal and abnormal tissue.

magnetic resonance imaging

[mag′ned·ik ′rez·ən·əns ′im·ij·iŋ]
(engineering)
A technique in which an object placed in a spatially varying magnetic field is subjected to a pulse of radio-frequency radiation, and the resulting nuclear magnetic resonance spectra are combined to give cross-sectional images. Abbreviated MRI.
References in periodicals archive ?
In all patients post-operative contrast MRI was performed 10 days after surgery for confirmation of IOUS findings and detection of residual tumour if any.
The achieved agreement between mean aICP and SD for the independently studied three groups of healthy volunteers is an evidence that phase contrast MRI method [16,17] and proposed ultrasonic method [13-15] of non-invasive absolute ICP measurement are free from systematic errors and do not need the calibration of the system "individual patient--non-invasive ICP meter".
The surgeon told her that they could do the contrast MRI and would carry out any necessary surgery the same day.
While performing preclinical hybrid imaging they felt to combine high soft tissue contrast MRI images with molecular information derived by PET.
McPherson, who had a contrast MRI Friday, is making his second trip to the DL this season after missing most of spring training and the beginning of the season because of a bad back.
On week four of each cycle, patients were evaluated with conventional and dynamic susceptibility contrast MRI to assess perfusion.
The use of Non contrast MRI in evaluating meniscal repair comparison with arthrography.
The two key findings using T1-weighted contrast MRI are meningeal enhancement and descent or sagging of the brain.
A contrast MRI will be performed today, which could clarify his prognosis.