Magnetic Resonance Imaging (MRI)
MRI scans produce cross-sectional images of your body by using a magnetic field, radio waves, and a computer. Information about bones, joints, and soft tissues is provided with precision.
An MRI machine or scanner is actually a tube surrounded by a large circular magnet. The magnetic field is created by passing electric current through coils contained in the housing of the machine for the purpose of aligning the protons of the body. Other coils emit radio waves that spin the protons and produce a faint signal. The signals are collected by the computer to produce an image. Very small changes in the body can be detected using MRI. If an MRI is ordered for you remember to: Tell the technician if you have metal implants or electronic medical devices in your body; tell the technician if you are claustrophobic; and remove any jewelry or metal accessories prior to the test.
An MRI scan is a painless procedure. The only discomfort may come from lying in one position during the test or the clanking noises produced by the MRI machine. Earphones are provided to reduce the noise. An MRI can take from thirty to ninety minutes. If you can remain calm and relaxed, it will go smoothly. You must lie still because any movement will blur the images.
Some doctors order contrast with the MRI scan. You may have an IV started at the beginning of your scan and at some point during the MRI scan a contrast agent is injected into the IV site. The purpose of the contrast is to obtain a better view of certain tissues.
There is contradictory information circulating about whether or not a patient who has a joint replacement can have an MRI scan. The magnetic field and metal implant may cause a problem; however, it depends on what type of metal is in the implant. Your doctor has that information and should be contacted prior to scheduling an MRI.
Your rheumatologist may order an MRI of your hand to establish a baseline for rheumatoid arthritis patients. Subsequent MRIs of the hand detect changes that correlate with disease progression. If there are no significant changes, that would suggest disease progression may have slowed and your treatment plan is effective.