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MRI of the head
Definition:
An MRI of the head is a non-invasive procedure that uses powerful magnets and radio waves to construct clear, detailed pictures of brain tissues. Unlike conventional radiography and computed tomography (CT), which make use of potentially harmful x-rays passing through a patient to generate images, MRI imaging is based on the magnetic properties of atoms. A powerful magnet generates a magnetic field roughly 10,000 times stronger than the Earth's. A very small percentage of hydrogen atoms within the body will align with this field. Text Continues Below
The "nuclear" in the original name (nuclear magnetic resonance imaging) -- now seldom used -- refers to the proton in the nucleus of the hydrogen atom and does not imply radioactivity. When focused short radio wave pulses are broadcast towards the aligned hydrogen atoms in tissues of interest, they will return a signal of their own. The subtle differences in that signal from dissimilar tissues enables the MRI to differentiate between various organs, and potentially, provide contrast between benign and malignant (cancerous) tissue. Any imaging plane, or slice, can be projected, and then stored in a computer or printed on film. MRI is easily performed through clothing and bones. However, certain types of metal in or around the area of interest can cause significant errors in the reconstructed images. These errors are called artifacts. Alternative Names:
Nuclear magnetic resonance - cranial; Magnetic resonance imaging - cranial; Head MRI scan; MRI - cranial; NMR - cranial; Cranial MRI
How the test is performed:
Since MRI makes use of radio waves very close in frequency to those of ordinary FM radio stations, the scanner must be located within a specially shielded room to avoid outside interference.
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