Magnetic Resonance Imaging (MRI) uses radiowaves and a strong magnetic field rather than xrays to produce detailed images of body tissues and organs. The magnetic field “excites” and then “relaxes” protons in the body, emitting radio signals. The radio signals are processed by a computer to form an image.
How should I prepare for my MRI?
The magnetic field used in MRI will pull on certain metal objects implanted into the body. The technologist will ask whether you have a pacemaker, brain aneurysm clips, artificial limbs, or any metal screws or plates. A patient with a pacemaker cannot have an MRI. In most cases, metal used in orthopedic surgery pose no risk during an MRI. You will also be asked if you have ever had a bullet or shrapnel in your body or ever worked with metal. If there is a possibility of metal shrapnel in the eyes, you will be asked to do an xray prior to the MRI.
Clothing should be free of metal. Watches and hearing aids must be removed. You may also be asked to remove hairpins, jewelry, removable dental work, glasses, body piercings or any other metal in the region of the body being scanned. Scrubs are provided to change into with private dressing rooms and secured lockers for valuables.
How long will my MRI examination take?
Usually the entire process will take an average of 45 minutes to 1 hour, allowing time also for paperwork and patient care. The exam time may vary from exam to exam. If you are having multiple exams allow extra time for each region being scanned.
Contrast agents used in MRI:
Gadolinium may be injected by a small needle into a vein in the patient’s arm during certain exams. The contrast will enhance abnormal tissue in the body, such as scar tissue in the spine after surgery, or tumors. The contrast is different than that used with CT Scans. The risk of an allergic reaction and kidney damage is very low. The amount of the contrast injected is determined by the patient’s weight.