The MRI is one of the most advanced diagnostic imaging methods available today. It uses simple radio waves in conjunction with a very powerful magnet; then a computer uses this information to generate realistic pictures of various parts of the body. MRI produces the most detailed images of soft tissues particularly the brain, spinal cord, muscles, ligaments and cartilage and is used mainly for evaluating these structures. But in the investigation of low back pain, MRI has a unique roll in looking at the shape and hydration of intervertebral discs and can determine if there is any pressure on nerves. Although CT can also image intervertebral discs, the detail obtained is not as great as MRI: on the other hand CT imaging provides better detail of bony abnormalities. The MRI is a large machine that has a circular tunnel built through it, like a donut with a hole. You will lie on your back on a narrow table that can be moved back and forth into the MRI tunnel. When the MRI is taken, expect to hear some loud noises from the machine. You will be asked to hold your breath for a few seconds for each picture that is taken. MRI scanners today vary in size and shape, and newer models have some degree of openness around the sides, but the basic design is the same. Once the body part to be scanned is in the exact centre of the magnetic field, the scan can begin. It may be difficult for some who suffer from claustrophobia (approx 2% of the population). If you think you might be someone who would require an anti-anxiety medicine to get through the procedure, you should discuss this with your doctor ahead of time. There are certain people who cannot be scanned for safety reasons. This includes people with pacemakers or certain other metal implants. Prior to having an MRI Scan you will be asked to fill in a simple questionnaire to ensure that there are no reasons why you should be excluded from the test. The examination takes around 30 to 40 minutes and there are no known side affects.