Magnetic resonance imaging (MRI) of the spine uses a powerful magnetic field, radio waves and a computer to generate detailed images of spinal structures, including the vertebrae, intervertebral disks, spinal cord and spinal nerves.
Unlike standard x-rays and CT scans, MRI does not use ionizing radiation. MRI uses magnetic and radio waves that are processed by a computer to create multiple, layered images of the spine.
MRI is often better at distinguishing abnormalities of soft tissue (muscle, nerves) than other diagnostic tests, such as x-rays. However, it may not be as effective at detecting abnormalities of the bones (vertebrae) as x-rays or CT scans. MRI of the spine may be ordered for a variety of reasons, including the following:
- to examine the intervertebral disks and joints that may be herniated or inflamed causing back pain and sciatica
- look for the presence of compressed and inflamed spinal nerves
- evaluate other possible causes of back pain, such as compression fractures due to osteoporosis.
- evaluate spinal infection or spinal tumors
- examine demyelinating lesions of multiple sclerosis (MS).
- plan for spinal surgeries that may be performed
- monitor changes after spinal surgery
The MRI may be used to evaluate specific portions of the spine depending on the symptoms. For example, the test may be limited to the cervical (neck) portion for those with neck pain, or the lumbar (lower) spine for those with back pain.
Performing a Spinal MRI
A spinal exam may take 20 to 45 minutes depending on the region being imaged.
MRI exams are painless, but some people find it difficult to remain still within the MRI scanner during the test due to claustrophobia. Sedation may be provided for those patients who have experience or at risk of having anxiety.
Metal and electronic objects can interfere with the magnetic field of the MRI unit so are not allowed in the exam room.
People with implants cannot be scanned and should not enter the MRI scanning area unless instructed to do so by a radiologist or technologist who is aware of the presence of any of the following:
- artificial heart valves
- implanted drug infusion ports
- implanted electronic device, including a cardiac pacemaker, or defibrillator
- cochlear ear implant
- clips used for brain aneurysms
- metal coils within blood vessles
- artificial limbs or metallic joint prostheses
- implanted nerve stimulators
- metal pins, screws, plates, stents or surgical staples
In general, metal objects used in orthopedic surgery pose no risk during MRI. However, a recently placed artificial joint may require the use of another imaging procedure. If there is any question of their presence, an x-ray may be taken to detect the presence of and identify any metal objects.
If a contrast material (gadolinium) will be used in the MRI exam, a nurse or technologist will insert an intravenous (IV) line into a vein in your hand or arm.
Infants and young children usually require sedation or anesthesia to complete an MRI exam without moving. Whether a child requires sedation will depend on the child’s age and the type of exam being performed.