What is a MRI Scanner, and how is it used clinically?
MRI stands for magnetic resonance imaging. It is an extremely powerful machine that is an invaluable diagnostic tool in the medical industry. An MRI machine uses a string magnetic field to produce high quality images in multiple planes/directions. These images are created using superconducting magnets and pulsing radio waves. MRI scans differ from x-rays in that they us non ionising radiation, whereas x-rays use radiation, which in high doses can be much more harmful.
MRI scanning has been widely used since the 1960’s and has no known side effects. It has become the investigative method of choice for musculoskeletal and neurological conditions, and is used across the entire body. In particular, MRI scanners work best in diagnosing issues with soft tissues and organs, including nerves, ligaments, tendons, and muscles. MRI scans can be extremely beneficial in investigating problems of the brain, heart, breasts, bones and joints, as well as all other organs.
Tho begin the MRI procedure, the patient will be asked to remove anything from their person that contains metal. This can be a problem for some patients who have metallic implants, pace makers, or even have metallic shrapnel in their body. In these cases, an MRI may not be possible.
Once anything that can be removed, is removed, the patient is asked to lie down on an examination table. This table is then reversed back into a tunnel like part of the machine. This this circular and allows the magnetic waves to rotate around the entire body. For this reason, an MRI scan can be very uncomfortable and often out of the question for anyone suffering from claustrophobia.
MRI scans take multiple full body scans and these each take around fifteen minutes, with brief pauses in between. A full MRI scan can be thirty minutes, to a full hour long, depending on what parts of the body are being scanned at the time.
Diffusion MRI measures the diffusion of water molecules in biological tissues. Diffusion MRI is used to diagnose primarily neurological conditions and helps to better understand the connectivity of white matter axons in the central nervous system.
Magnetic resonance angiography or MRA, generates pictures of arteries to examine them for problems such as stenosis, which means abnormal narrowing, or aneurysms, which means vessel wall dillation or risk of rupture.
Magnetic resonance spectroscopy or MRS is used to measure the levels of different levels of metabolites in body tissue. This allows it to diagnose certain metabolic conditions and gain information on tumor metabolism.
Functional MRI or fMRI, measure signal changes in the brain due to changing neural activity. This can be used to glean more information on how the brain develops and works.
Real time MRI is in reference to the continuous monitoring of moving objects in real time. New methods for this promise to give important information about diseases of the heart and joints
Interventional MRI is where the images produced by MRI scanning is used to guide procedures that are minimally invasive.