Magnetic Resonance Imaging (MRI)

Spine specialists can often tell what’s wrong with your back just by looking at you and performing some screening tests (the straight leg raise test for sciatica comes to mind). Sometimes, though, they need to look in you instead of just at you, and that’s where imaging studies come into play.

X-rays, the most famous imaging technique, are great for showing bone…and not much else. For the soft tissue injuries that that cause the vast majority of back pain cases—think muscle strains, disc herniations, and others—the MRI is the better choice.

Magnetic resonance imaging (MRI) is a noninvasive medical imaging technology performed by a radiologist to help detect and diagnose spinal disorders. Unlike an X-ray or CT scan (computed tomography), an MRI scan does not require radiation to produce pictures of your spinal anatomy.

Closed MRIA closed MRI scanner system can induce claustrophobia in some patients. Photo source: iStock

How Spine MRIs Work

The MRI’s powerful magnet and radio waves interact with your body’s water and fat molecules to create detailed images of the spine’s soft tissues and bone. The spinal cord, nerve roots, blood vessels, ligaments, muscles, intervertebral discs and endplates are soft tissues. Bone tissue includes the vertebral bodies and adjacent structures, such as the facet joints.

An MRI scan may be performed with or without contrast, which is a medical dye (e.g., gadolinium) injected into a vein to enhance visibility and clarity of the image. Tissues that collect more contrast appear brighter than surrounding tissue and may provide more detail about disorders such as a spinal tumor, bone cancer, infection (vertebral osteomyelitis) or inflammation.

Advanced MR imaging technology is one of the most valuable spinal assessment tools available. Physicians rely on MRI to evaluate:

…and many other disorders.

Lumbar, low back MRIsSagittal (lateral) MR imaging of the lumbar spine shows ‘slices’ of the lower back’s anatomy including the discs and spinal cord. Photo source: iStock

Types of MRI Machines

Most MRI machines are large and located in a hospital or large radiology facility. However, newer types of MRI units have small footprints allowing installation in a physician’s office or clinic. Having MR imaging available within a physician’s practice makes it possible for a patient to undergo an MRI scan the day of their appointment.

MRI machines are described according to their design differences:

  • Closed MRI
  • Wide bore MRI (partly open)
  • Open MRI
  • Open upright
  • Open tilting

The physician who orders the MRI scan considers your comfort during the examination. This includes your body size and risk for claustrophobia.

  • An open MRI setting can help reduce anxiety, fear of confinement in a small space, and other symptoms related to claustrophobia.
  • The open upright MRI machine creates weight-bearing images while you are standing or sitting.
  • The open tilting MRI (Esaote G-scan Brio Dedicated MRI) represents the latest technology. The tilting MRI design allows the radiologist to rotate you from a laying position (called supine) into a weight-bearing position anywhere from zero to 90-degrees.

Esaote G-scan Brio Dedicated MRI SystemThe Esaote G-scan Brio Dedicated MRI system combines an open and weight-bearing MR imaging experience. Image provided courtesy of © Esaote North America.

The open tilting weight-bearing MRI provides your physician more diagnostic information and the opportunity to compare both supine and weight-bearing images. A benefit of weight-bearing MRI diagnostic imaging is it visually demonstrates gravity’s effect on a spinal disorder.

Minimizing Potential MRI Risks

Usually, the day before your MRI scan appointment a radiology technician contacts you to review your medical history. This process involves asking you questions specifically related to undergoing an MRI study. Questions may include:

  • If you’ve had a previous MRI, did you experience any problems?
  • Do you have an eye or other body injury involving a metal object or fragment (e.g., metallic slivers, bullet, shrapnel)?
  • Are you allergic to any medication?
  • Have you had a reaction to a contrast dye used for MRI, CT or X-ray examination?
  • Do you have a history of asthma, respiratory disease, kidney disease, liver disease, high blood pressure, diabetes, seizures, transplant?
  • Do you have a movement disorder?
  • Are you pregnant or breastfeeding?

The MRI magnet is extremely strong and can instantly pull a metallic object into its magnetic field. Certain medical devices and implants inside or on your body can create a dangerous situation if you enter the MRI system room or undergo an MRI examination. Therefore, the technician carefully reviews a list of hazardous devices made from metals that you may have in/on your body. These include:

  • Aneurysm clip(s)
  • Cardiac pacemaker
  • Neurostimulation system, spinal cord stimulator
  • Cochlear ear implant
  • Insulin or other infusion pump
  • Spinal shunt
  • Joint replacement (eg, hip, knee, shoulder)
  • Tattoo or permanent makeup

Arrange ahead of time to be driven the day of your MRI appointment if you become claustrophobic in small or confined places. Patients who are claustrophobic may be sedated and not allowed to drive for 24 hours.

Preparing for Your MRI Scan

When you arrive at the MRI facility, you are escorted to a dressing room where you change into a gown and secure your personal items in a locker. Before you are allowed to enter the MRI system room, you must remove any metal objects such as your cell phone, keys, eyeglasses, jewelry, hair pins, coins, pens, paper clips, hearing aids, and credit cards.

If your MRI exam involves contrast, the radiologist or MRI technician prepares either your arm or hand for an intravenous (IV) line. The contrast dye (e.g., gadolinium) is injected through the IV prior to your MRI with contrast.

What to Expect From Your Spine MRI

The radiologist or radiology technician assists you onto the MRI scanner bed and positions you for the exam. Positioning may involve placement of foam pads and/or cushions to stabilize your body position and provide comfort. Earplugs or headphones are provided to wear during the scan to help block out loud thumping and tapping noises that normally occur during the MRI examination.

A closed MRI can be tight, and some patients may experience claustrophobia, which is nothing to be ashamed of. If you often get claustrophobic or start to feel claustrophobic in the machine, tell your radiologist or tech and they’ll do their best to talk you down and make you more comfortable.

The radiologist controls the MRI from a glass-enclosed room adjacent to the MRI machine. Throughout the entire exam, you are observed and spoken to through a two-way intercom. Periodically, the technician may ask you to hold your breath or stay very still for a few seconds.

An MR imaging scan can take 15 to 60 minutes depending on the size of the body area being examined and the number of images ordered.

After the exam, the IV is removed (if your MRI was with contrast) and safely helped up and off the scanner bed. You return to the dressing room and change into your clothes. If you received sedation, you are allowed to go home after you are awake and alert. If you received sedation, you must have someone drive you home.

Getting Your MRI Results

After performing the MRI examination, the radiologist interprets your images and sends a detailed report to your spine specialist. The MR images are saved using a secure picture archiving system and can be electronically sent to be viewed on a monitor (and other devices) in the clinic and/or operating room.

So, what does it all mean? Your spine specialist will use your MRI results to confirm a diagnosis. Since back pain has so many possible causes, getting a firm diagnosis is the first step to feeling better. Armed with your MRI results, you and your spine specialist can begin your treatment.

Updated on: 02/24/21
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