MRI or magnetic resonance imaging scan is an imaging test that creates pictures of internal body structures (bones and soft tissues) with the help of magnetic fields and radio waves.
The MRI can also be combined with other imaging techniques to provide a more definitive diagnosis. The scan is often used to clarify findings from previous X-rays or CT scans.
MRI scans provide information on a variety of conditions and procedures and to assess function of the internal organs such as:
- Brain and spinal cord abnormalities
- Prostate, liver and breast abnormalities
- Function and structure of the heart
- Joint problems
- Blood flow through blood vessels
- chemical composition of tissues
- Tumor detection and help in staging (tumor size, severity and spread)
Before the procedure, you will be asked to remove any metallic devices such as hearing aids, hairpins, removable dental work or other objects that may interfere with the procedure. You may be provided with ear plugs or music to block the strong noises from the MRI scan. You may be sedated if required.
The MRI machine consists of a large strong magnet and a table that moves into the opening of the scanner. During the procedure, you will be asked to lie on the table, which will be advanced into the scanner. The machine creates a magnetic field that creates loud noises. In some cases, a contrast dye may be injected through your arm to provide a clearer view of the scan. A radio wave antenna directs signals to the body and receives them back to create images by a computer attached to the scanner. You need to keep very still throughout the scan as movement may blur the resulting images. The entire procedure may take up to an hour to complete.
If you were not sedated, you may resume your usual activities immediately after the MRI. If you have been given a sedative, you will need to arrange for a relative or friend to take you home after the scan.
Things to bring for MRI examination
- Please bring relevant prior imaging studies if they were performed at an outside facility.
- On the day of your exam, bring your insurance card, and any related insurance information.
- If you have an implanted medical device, please have your implant card available.
Advantages & Disadvantages
Advantages of MRI include:
- Does not use radiation
- Is noninvasive
- Can take images of any part of the body from almost any direction and orientation
- Produces better images of soft-tissue structures compared to other imaging techniques
- Can differentiate between tissues based on their biochemical properties such as water, fat, iron
- Can scan large regions of the body
Disadvantages of MRI include:
- Certain patients who get nervous in small spaces (claustrophobic) may not be able to have an MRI.
- Elderly or ill patients may find it difficult to cooperate, which may result in blurred images.
- MRI can not be done on patients with implanted medical devices such as aneurysm clips in the brain, heart pacemakers and cochlear (inner ear) implants
- MRI is an expensive procedure
- Some patients may find it difficult to lay still during the entire exam, especially when the exam is ordered to evaluate a joint that is already painful. If you can anticipate this ahead of time, it is important to consider whether a pain reliever may help prior to the exam.
Risks and complications
Since an MRI scan is a noninvasive test, it is a very safe procedure. However, there is a very small risk of an allergic reaction to the contrast dye or sedation medicine if used. Any metal or electronic devices in your body are a safety threat and you should not undergo an MRI in those circumstances. Before your MRI test, make sure you notify your doctor and the MRI technologist if you:
Have any health conditions, such as kidney or liver problems that may prevent you from having an MRI using contrast material
Are pregnant as the effects of magnetic fields on the baby are not yet known
What is contrast?
Sometimes, intravenous or intra-articular contrast is ordered with your examination, and provides additional important details to aid in the diagnosis. Unlike iodinated-contrast material used for CT scans, gadolinium-based contrast may be used during your MRI examination. Gadolinium rarely causes an allergic reaction, however, if you have a history of health problems related to your kidneys, please inform the office prior to your examination. If you have questions at the time of your examination, the MRI technologist and/or radiologist will be available to answer your questions.
MRI arthrography is evaluation of the joint following the intra-articular administration of contrast material. In general, contrast can be administered into the joint using fluoroscopy (live x rays), CT, or ultrasound.
Dr. Carpenter prefers the use of ultrasound for several reasons:
- No ionizing radiation.
- No additional contrast material is administered.
- Patients are generally more comfortable.
Patient safety tips prior to an arthrogram
- Please let us know if you have any allergies or adverse reactions to medications.
- If you are pregnant or may be pregnant, please notify the radiology staff prior to or at the time of your appointment.
- If you are taking blood thinning medications, please notify the radiology staff prior to or at the time of your appointment.
Preparation for the procedure
- You will be given a contrast screening form to complete.
- There will be an opportunity for you to talk with Dr. Carpenter about the procedure, ask any questions, and give your consent.
During the procedure
- The duration of the procedure may vary, but on average, the procedure will take about 10-15 minutes.
- Dr. Carpenter will be available to answer any questions.
After the procedure
- You should rest the joint as much as possible for 24 hours after the procedure.
- If you have swelling or tenderness in the joint, apply ice intermittently.
- You may take over-the-counter pain reliever
- If swelling or tenderness lasts more than 2 days, please contact our office.