MRI Scanning
A Magnetic Resonance Imaging (MRI) scanner uses a strong magnetic field and radio waves to produce detailed pictures of the inside of your body.
MRI scans can show muscles, joints, bone marrow, blood vessels, nerves and other structures within your body.The images the scans produce are usually two-dimensional, but in some cases several different scans can be taken to build up a three-dimensional image that can be displayed on a computer screen.
MRI scans are commonly used to examine the brain, spine, abdomen and pelvis.
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How does MRI Scanning work?
The human body contains a large number of water molecules, which contain hydrogen atoms. The powerful magnet in an MRI Scanner pulls these atoms so that they line up with the direction of the magnetic field.
The scanner then sends short bursts of radio waves into the part of the body being scanned, which makes the magnetic field of some hydrogen atoms in that part change direction. When the radio waves are switched off, the magnetic field of these hydrogen atoms moves back to its original position.
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An MRI scan is painless, but there are some people who cannot take an MRI scan because of particular conditions for example, if you have a pacemaker. You will be asked to fill out a declaration form which asks questions about whether you have a pacemaker or other metal objects in your body. You will also be required to remove all metal objects, such as jewellery.
It is important to be as comfortable as possible during the scan, it is very important to keep very still whilst being scanned to avoid blurring the images. A scan can vary in duration from 15 – 60 minutes depending on the area being scanned. You will be given headphones to wear as the scanner makes a loud knocking noise whilst in use.
After the Scan
Once the scan is over, most people can resume their normal activities. If you have been given an injection of contrast dye, you will be advised to drink plenty of water during the 24 hours following your scan, to flush the dye out of your body. The dye is not harmful but some people may get an allergic reaction.