WHAT YOU SHOULD KNOW ABOUT MAGNETIC RESONANCE IMAGING

by Lorenzo G. Walker, M.D., F.A.A.O.S.

Surgery of the Hand and Upper Extremity

Dr. Walker has ordered an MRI scan in an effort to speed your diagnosis and provide you with the best possible care.

WHAT IS AN MRI?

Magnetic Resonance Imaging is tremendously important in the field of orthopaedics as it is a way to look "inside the body" without using x-rays. Dr. Walker will use the MRI to produce two or three-dimensional images of exactly what is occurring in your neck, shoulder, elbow, wrist, or hand. The images produced by this study are extremely precise, and MRI therefore has the potential to reduce the number of diagnostic surgeries by providing similar information in a non-invasive fashion. Contrary to popular belief, MRI uses no x-rays, and the magnetic fields the MRI produces are not known to be harmful.

An MRI scanner works in the following fashion: All of the tissue in your body is composed of tiny particles called atoms. The magnet in the scanner analyzes the alignment of a portion of the atoms called protons. This gives precise information about the tissues and their anatomy.

A computer is the final common pathway for all of this data. It uses the information to construct an image on a TV screen, showing the alignment of these protons within the tissue. The screen image is recorded on film or magnetic tape so that there is a permanent copy, which is made available for you and your physician.

Uses of Magnetic Resonance Imaging are invaluable in orthopaedic surgery, as MRI can detect injuries, disorders, and diseases affecting tendons, ligaments, cartilage, nerves, bone marrow, and vascular structures (arteries and nerves).

PREPARING FOR THE MRI SCAN

QUESTION: What should I do before the exam?

ANSWER: You can do everything you normally do, including eating, drinking, and working as usual. Continue taking all prescription medications.

QUESTION: Are there any restrictions with the exam?

ANSWER: Yes. It is not recommended that you undergo the MRI examination if you have a pacemaker, cerebral aneurism clips, cochlear implants, or if you have any implant within your body made of magnetic materials. There are also restrictions about what you can have with you during the exam. Please do not bring any of the following into the examination room: Coins, jewelry, watches, keys, dentures or partial plates, or hearing aids. (Magnetic waves can erase credit card codes, too, so avoid having any of them on your person.)

QUESTION: What happens during the MRI examination?

ANSWER: Before the scan, a technologist will help you position on the scanning table. Generally, you will be asked to lie on your back and the surface coil may be attached to the part of your body which deserves the most concentration. If a contrast agent is needed, you will be given an injection. This contrast agent improves the quality of certain images. Let the technologist know if you feel nausea or other discomfort. As the scan begins, the scanning table will slide into the interior of the giant magnet, which is like a tunnel, open at both ends. If you feel anxious, you can generally talk to the technologist over an intercom, or signal for attention in some way. THE MRI SCAN IS COMPLETELY PAINLESS.

The only thing you will have to remember while the machine is working is to remain as still as possible to ensure the clearest possible pictures. Movement during an MRI scan can cause the images to blur and can cause problems with interpretation.

Once the scan is finished, the images are reviewed for quality. If more images are needed, they will usually be taken right away. If you were sedated, you may be asked to stay a while for your own safety.

QUESTION: Who evaluates the results of the MRI scan?

ANSWER: The results of the MRI scan are generally evaluated initially by the radiologist. He or she will share the findings with Dr. Walker, who will review the films independently before discussing them with you, the patient.

COMMON QUESTIONS

QUESTION: Can pregnant women have MRI scans?

ANSWER: Although there is no evidence that a hazard exists, MRI is generally not advisable during pregnancy, especially during the first trimester. In critical cases, a scan may be recommended by your health care provider and an appropriate discussion should ensue.

QUESTION: Will the fillings in my teeth affect the scan?

ANSWER: The fillings in your teeth may cause some distortion in images taken about the mouth area. Please tell your health care provider and the scanning technologist if you have braces or permanent bridges.

QUESTION: Are MRI scans expensive?

ANSWER: Yes. Because the equipment is so costly, scan costs are high. Dr. Walker's office will ensure that your insurance has agreed to pay for your scan before embarking on this study.

QUESTION: How long does an MRI scan take?

ANSWER: Total scanning time usually ranges from 30-90 minutes.

QUESTION: Can people with metal implants be scanned?

ANSWER: In general, an MRI scan cannot be done if a person's body contains an implanted electronic device, such as a cardiac pacemaker or a metal object that contains iron, as the object may be moved out of place by the magnetic force. Let the scan technologist know if you have any metal implants. He or she will then determine if you can indeed go ahead with an MRI scan.

QUESTION: I have been asked if I am claustrophobic. What does this mean?

ANSWER: Claustrophobia is a fear of confined spaces and is fairly common.

Being in a confined space, such as a magnetic resonance scanner, can arouse these feelings. If you know you are claustrophobic, or weigh more than 250 pounds, an "open air" MRI may be best for you.

Several hospitals in the Ventura County area (e.g. Westlake Hospital, Simi Valley Hospital) have "open air" scanners. These can significantly reduce the claustrophobia experienced by susceptible patients.

This handout was prepared by Dr. Walker so your questions about MRI scanning are answered and to enhance your comfort with the procedure. Please let him know if you have any other questions.