An MRI, or a magnetic resonance imaging scan, can help doctors monitor treatment, or diagnose an injury or disease. Scans can be performed on different areas of the body to detect things like cancer, brain injuries, stroke, heart disease, liver and kidney health, and joint damage.
If you’ve never had an MRI, you may be wondering how safe the procedure is.
How Do MRIs Work?
An MRI machine uses a large magnet that connects to a computer to take pictures of the body part being scanned. Each picture shows different layers of body tissue. When the procedure is complete, the photos are examined on a computer monitor.
Before the scanning process begins, doctors inject a substance called gadolinium into the veins to help produce a clear image. When testing for cancer, gadolinium collects around cancer cells, so they will show up brighter on the picture.
Scans can take anywhere from 15-90 minutes to complete, but the entire examination (including the scan) can take up to three hours.
The MRI machine creates a marge magnetic field around the patient. The magnetic field, coupled with a radiofrequency, alters the hydrogen atoms’ natural alignment.
Potential Risks of MRIs
MRI machines use radio waves, but no radiation is used. There is no risk of exposure to radiation during the scanning process.
But because of the strong magnet inside of the machine, MRIs cannot be performed on people with:
- Certain prosthetic devices
- Bone-growth stimulators
- Cochlear implants
- Implanted pacemakers
- Intracranial aneurysm clips
- Certain intrauterine contraceptive devices
- Any type of iron-based metal implant
- Internal metallic objects, such as bullets, shrapnel, pins, plates, metal sutures, wire mesh, etc.
MRIs are generally not recommended for pregnant women and those with epilepsy.
How Safe is an MRI?
Doctors and medical experts maintain that MRIs are safe as long as the patient is a good candidate for the procedure. But in recent years, there has been some controversy surrounding the gadolinium-based agents, or GCBAs) used in the procedure.
The biggest concern is that gadolinium is a heavy metal. Essentially, patients are willingly injecting heavy metals into their bodies.
A study from 2014 showed that gadolinium is retained in some organs, including the brain, and bones. The FDA acknowledged in 2017 that gadolinium deposits can remain in the brain for years after the injection, but there is no substantial evidence that shows gadolinium deposits are harmful.
There is also the risk of an allergic reaction to GCBAs. According to Massachusetts General Hospital, reactions are extremely rare and not life-threatening. But it is possible for GCBAs to cause a potentially-fatal thickening of nephrogenic systemic fibrosis, a type of soft tissue. Mass General acknowledges that there is evidence that trace amounts of GCBAs can accumulate in the central nervous systems of patients who have had several MRIs. The risks associated with this accumulation are still unknown.
There is also some evidence that GCBAs can cause side effects, like kidney damage and cognitive issues. There are many different types of GCBAs, and some are considered less risky than others. It’s important to do your research and weigh your options with your doctor before your MRI procedure if you’re concerned about the safety of GCBAs.