Magnetic Resonance Imaging of the Bones, Skeletal MRI
Bone MRI uses a strong magnetic field combined with radiofrequency waves to create highly detailed, cross-sectional images of selected bones and surrounding tissues. These scans, which appear as two-dimensional slices through the bone, are then examined for abnormalities. For certain studies, an MRI contrast dye such as gadolinium may be injected to provide better definition of soft tissues and blood vessels and thus enhance the images.
Purpose of the Bone MRI
- To diagnose tumors (primary tumors and metastases) of the bone or the soft tissue inside or around the bone, such as muscles and ligaments
- To pinpoint any changes in the bone marrow cavity.
- To assess various disorders of the spine, spinal cord, spinal nerves, or intervertebral discs, and to evaluate the spine before surgery
- To help diagnose and evaluate degenerative joint disorders, such as arthritis, and injuries of the knee, shoulder, and hip ligaments and tendons(e.g., meniscal tears in the knee, labral tears of the shoulder and hip)
- To diagnose and assess fractures in some patients
- To examine the spinal cord after injury
- To assess sports- and work-related injuries caused by repetitive strain, vibration or forceful impact
- To detect infections, including osteomyelitis
- To monitor tissues in and around the joints for pain, swelling or bleeding
Who Performs Bone MRI
- A radiologist or a qualified technician
Special Concerns about Bone MRI
- MRI is more expensive and less widely available than x-rays or CT scans, but is preferable in most cases where differentiation of the soft tissue in and around bones is necessary.
- People who experience claustrophobia may find it difficult to undergo an MRI, which takes place in a narrow, tunnel-like structure. In some cases, an open MRI—a larger unit that is open on several sides—may be used as an alternative.
- This test may not be possible for severely overweight individuals (over 300 lbs), although some open MRI scanners can now accommodate larger patients.
- Because the MRI generates a strong magnetic field, it cannot be performed on people who have certain types of internally placed metallic devices, including pacemakers, inner ear implants, or intracranial aneurysm clips.
- The test is not commonly done in pregnant women because the long-term effects of MRI on the fetus are unknown.
Before the Bone MRI
- Tell your doctor if you suffer from claustrophobia. He or she may prescribe a sedative that can help you tolerate the procedure.
- You will be advised to empty your bladder before the test.
- Remove any magnetic cards or metallic objects, including watches, hair clips, belts, credit cards, and jewelry. You may be asked to disrobe and put on a hospital gown.
What You Experience during Bone MRI
- You will lie down on a narrow, padded bed that slides into a large, enclosed cylinder containing the MRI magnets.
- You must remain very still throughout the procedure because any motion can distort the scan.
- In some cases, you will receive an injection of contrast dye such as gadolinium before or during the procedure.
- There is a microphone inside the imaging machine, and you may talk to the technician performing the scan at any time during the procedure.
- You will hear loud thumping sounds as the scanning is performed. To block out the noise, you can request earplugs or listen to music on earphones.
- The procedure usually takes from 60 to 90 minutes.
Risks and Complications of Bone MRI
- MRI does not involve exposure to ionizing radiation and is not associated with any risks or complications.
After the Bone MRI
- Most patients can go home right after the scan and resume their usual activities.
- Sedated patients may be monitored for a short period until the effects of the sedative have worn off.
Bone MRI Results
- The MRI scans are displayed on a video monitor and then recorded on film. The doctor will examine the images for signs of any skeletal abnormality.
- If a definitive diagnosis can be made, appropriate treatment will be initiated, depending on the specific problem.
- In some cases, additional tests, such as a bone biopsy, may be required to establish a diagnosis or determine the extent of a problem.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media