MRI (magnetic resonance imaging)

This test is similar to a CT scan, but uses magnetic fields instead of x-rays and takes place with the patient lying on a couch inside a metal cylinder.

The cylinder is a very powerful magnet, so patients with any metal inside their body, for example, a cardiac monitor, pacemaker, surgical clips, or bone pins, may not be able to have an MRI because of the magnetic fields.

An injection is usually given to allow the images to be seen more clearly.  The test can take about 30 minutes and is completely painless.