A magnetic resonance imaging (MRI) scan is a common procedure that we use to evaluate the site and severity of an injured area. MRI uses a strong magnetic field and radio waves to create detailed images of the organs and tissues within the body. The development of MRI revolutionized the medical world. Since its discovery, doctors and researchers have refined techniques to use MRI scans to assist in medical procedures and help in research. An MRI scan is a non-invasive and painless procedure.
What is an MRI scan?
An MRI scan uses a large magnet, radio waves, and a computer to create a detailed cross sectional image of the patient’s internal organs and structures. The scanner itself typically resembles a large tube with a table in the middle, allowing the patient to slide into the tunnel. An MRI scan differs from CT scans and X-rays because it does not use ionizing radiation.
The following are just some of the examples where an MRI scanner is used:
- Abnormalities of the brain and spinal cord
- Tumors, cysts, and other abnormalities in various parts of the body
- Injuries or abnormalities of the joints, such as back pain
- Certain types of heart problems
- Diseases of the liver and other abdominal organs
- Causes of pelvic pain in women (e.g. fibroids, endometriosis)
- Suspected uterine abnormalities in women undergoing evaluation for infertility
Preparing for an MRI scan
There is little to no preparation required for patients before an MRI scan. On arrival to the MRI location, doctors may ask the patient to change into a gown. Large magnets are used, so it is critical that there be no metal objects in the scanner, so you will be asked to remove any metal jewelry or accessories that may interfere with the machine.
Sometimes, patients will be injected with intravenous (IV) contrast liquid to improve the appearance of a certain body tissue. The radiologist will then talk the individual through the MRI scanning process and answer any questions they may have about the procedure.
Once the patient has entered the scanning room, they will be helped onto the scanner to lie down. Staff will ensure that they are as comfortable as possible by providing blankets or cushions. Earplugs or headphones will be provided to block out the loud noises of the scanner. The latter is very popular with children as they can listen to music to calm any anxiety.
How does an MRI scanner work?
An MRI scanner contains two powerful magnets; these are the most important parts of the equipment. The human body is largely made of water molecules, which are comprised of hydrogen and oxygen atoms. At the center of each atom lies an even smaller particle called a proton, which serves as a magnet and is sensitive to any magnetic field.
Normally, the water molecules in our bodies are randomly arranged, but upon entering an MRI scanner, the first magnet causes the body’s water molecules to align in one direction, either north or south.
The second magnetic field is then turned on and off in a series of quick pulses, causing each hydrogen atom to alter its alignment and then quickly switch back to its original relaxed state when switched off. The magnetic field is created by passing electricity through gradient coils, which also cause the coils to vibrate, resulting in a knocking sound inside the scanner.
Although the patient cannot feel these changes, the scanner can detect them and, in conjunction with a computer, can create a detailed cross-sectional image for the radiologist to interpret.
How long will an MRI scan take?
MRI scans vary from 20-30-minutes depending on what part of the body is being analyzed and how many images are required. If, after the first MRI scan, the images are not clear enough for the radiologist, the patient may be asked to undergo a second scan straight away.