Magnetic Resonance Imaging is an investigative procedure to detect structural or anatomical problems inside the body without the need for exploratory surgery or more complex invasive tests. MRI scanning is a painless way to "see" through bones.

It can be used to detect problems in almost any area - head, brain, eyes, ears, neck, chest, abdomen, pelvis, spine and limbs. It is particularly useful for detecting nerve root compression (pinched, trapped nerves) in the spine by a slipped disc and is also commonly used to assess major joints (knees and ankles - torn ligaments, meniscus injuries).

During a Magnetic Resonance Imaging scan, radio waves are directed at protons, the nuclei of hydrogen atoms, in a strong magnetic field. The protons are first "excited" and then "relaxed" emitting radio signals, which can be computer processed to form three dimensional computerized sectional images of various parts of the body. Unlike other imaging methods, MRI does not use X-rays and has no known side effects.

In the body, protons are most abundant in the hydrogen atoms of water, so that an MRI image shows the differences in the water content and the distribution in various body tissues. Even different types of tissues within the same organ can be easily distinguished, such as they grey and white matter of the brain.

MRI has found wide applications in many branches of medicine. Neurology, cardiology, orthopedics, urology and general surgery all use MRI for making and confirming diagnosis. MRI can also be used in angiography studies without the need for contrast. MRI scans produce detailed pictures of soft body tissue and organs without using ionizing radiation, making early detection of cancers, neurological and musculoskeletal diseases possible.

An MRI machine contains a very large super conducting magnet, a radio-wave transmitter and a computer that together construct detailed pictures of parts of the body. This procedure is 5-10 times more accurate than anything else available including the CT scan.

Simple scans that do not require an injection can be done by a technician without a physician present. Scans that require a contrast agent (e.g. bowels, etc.) must be administered by a physician.

Due to capital acquisition costs and a shortage of trained staff to operate and maintain these machines, waiting lists for MRI scans in Canada have become lengthy.