MRI Stands for Magnetic Resonance Imaging. MRI is a way of getting pictures of various parts of your body without the use of X-rays. Unlike X-rays and computed tomographic (CT) scans, which use radiation, a MRI uses powerful magnets and radio waves. A radio wave antenna is used to send signals to the body and then receive signals back. These returning signals are converted into pictures by a computer attached to the scanner. Pictures of almost any part of your body can be obtained at almost any particular angle.
Is MRI Safe?
MRI is quite safe in the majority of patients. Certain patients may not be able to have an MRI. These include people who get nervous in small spaces (claustrophobic) and those with implanted medical devices such as aneurysm clips in the brain, heart pacemakers and cochlear (inner ear) implants. Also, people with pieces of metal close to or in an important organ (such as the eye) may not be scanned. There are a few additional safety considerations and some exceptions based on individual circumstances.
Why is the MRI Test Performed?
This test may be used to diagnose or evaluate:
- Shoulder pain or instability
- Knee pain or instability
- Hip pain
- Elbow pain
- Back pain
Combining MRIs with other imaging methods can often help the doctor make a more definitive diagnosis. MRI images taken after a special dye (contrast) is delivered into the body may provide additional information about the soft tissues around a joint.
It is often used to clarify findings from previous X-rays or CT scans. A pad is placed on the patient’s abdomen to help make the pictures clearer.
Advantages & Disadvantages
Advantages of MRI include diagnosing:
- Spine, or joint infections
- Visualizing torn ligaments in the wrist, knee, and ankle
- Visualizing shoulder injuries
- Herniated discs in the spine
MRI also has disadvantages
- People with pacemakers cannot have MRIs.
- Patients who are morbidly obese may not fit into an MRI system.
- Claustrophobic patients often cannot make it through a MRI. These patients may require sedatives or an Open MRI, which is an MRI system that is not completely closed around the patient. The MRI at Kern Bone and Joint Specialists is an Open MRI. This is a much less enclosed type of MRI and is often better tolerated by patients with claustrophobia than other types of MRI.
- The MRI machine makes a some amount of noise during a scan. The noise sounds like a continual, rapid hammering. The noise is due to the rising electrical current in the wires of the gradient magnets being opposed by the main magnetic field. The stronger the main field, the louder the gradient noise. Patients are given earplugs or stereo headphones to muffle the noise.
- MRI scans require patients to hold still for extended periods of time. MRI exams can range in length from 20 to 45 minutes or possibly more.
- MRI systems are very expensive. Therefore the exams are also very expensive.
Preparation for MRI Test
Before your MRI test, tell your health professional and the MRI technologist if you:
- Are allergic to any medicines
- If you are or might be pregnant
- If you wear any jewelry, eyeglasses, hearing aids, hairpins, removable dental work or other objects that may interfere with the procedure.
- Have any other health conditions, such as kidney problems that may prevent you from having an MRI using contrast material.
- Had recent surgery on a blood vessel, in some cases you may not be able to have the MRI test.
- Wear any medication patches. The MRI may cause a burn at the patch site.