MRI Scans: Are They Dangerous?

CT Scan

Magnetic resonance imaging (MRI) has been the technology of choice for creating clear and crisp images of internal organs, helping doctors make sound diagnoses. It saves lives by alerting doctors to more severe health issues, like cancer hiding underneath unassuming symptoms like body pain. Although costly, undergoing a full body MRI scan is a valuable expense when lives are at stake.

However, nothing made by human hands is without risks, MRI machines included. Three years ago in India, an MRI machine claimed a man’s life after it yanked the oxygen tank from his hand and ruptured it, causing him to breathe toxic oxygen. For a more recent example, a British teenager in 2019 died from complications due to the anesthetic given before her MRI scan.

These reports aren’t isolated cases as similar incidents have happened over the decades. And, every time they happen, the safety of MRI technology is being called into question. This in-depth look into the procedure hopes to provide closure to the controversies.

A Brief Rundown

Credit for the first full-body MRI system goes to American physician Raymond Damadian and his machine he called the ‘Indomitable.’ However, the technology that made it possible goes way back to Nikola Tesla’s rotating magnetic field concept in 1882. Applying an electrical charge to a set of coils creates rotations whose magnetic waves cover an object in full spectrum.

Unlike computerized tomography (CT) or x-rays, MRI doesn’t use potentially harmful radiation. The magnetic fields generated, between 0.5 and 1.5 teslas, are relatively safe to the human body. On top of that, operators can adjust the magnetic strength from head to toe, minimizing exposure on areas that don’t need MRI scanning.

Because most diseases usually manifest as increased water content, MRI manipulates the hydrogen atoms in water. As the magnetic field neatly arranges these atoms, radio waves resonate with them. The result is an image that outlines the unusual amount of water in an organ, a red flag in itself.

It’s Not For Everyone

As now established, MRI employs magnetic fields and radio waves. Considering earth’s magnetic field generates 0.5 teslas, an MRI machine rated at 1.5T means its magnetic fields are 30,000 times stronger than Earth’s. It’s more than enough to turn the oxygen tank from earlier into a projectile.

The intense magnetism also comes to mind one safety risk: patients with implants. MRI machines can displace pacemakers, metal prosthetics, dental screws, and other iron-based implants, causing a severe malfunction. It’s for this reason that CT scans and x-rays remain widely used. 

You can determine if your medical device is safe in an MRI by looking at its MR safety label. The Food and Drug Administration requires such devices to sport one of these three ratings.

  • MR-Safe – The device poses no risk to the patient and the procedure. The label features a green circle, with the MR label in green inside a white square.
  • MR-Conditional – The device is safe for MRI under specific conditions stated on the label. It has a yellow circle, with the MR label in black inside a black-and-yellow triangle.
  • MR-Unsafe – The device isn’t deemed safe for MRI. The label sports the MR label crossed out by the universal no symbol. 

Doctors also advise pregnant women against undergoing MRI. While multiple studies have found little to no evidence of harmful effects, researchers still aren’t sure about the impact the MRI will have on the baby. If an MRI scan is a must, it’s advisable to wait until three months into pregnancy.

Safety Precautions

When performed by capable hands, MRI images can paint a clear picture of a patient’s health sans the risk. MRI should be the go-to procedure for high-risk patients, namely those at risk of brain or heart disease, overweight or obese, or over 45 years old.

It’s important to note that most deaths linked to MRI involve the strong magnetic field it generates. The first recorded case of such an accident happened in 2001 with a six-year-old from New York. As the child underwent an MRI scan, the magnetic field sent a nearby oxygen tank flying into the core, dealing a fatal blow to the head.

Turning off the machine isn’t generally an option except for after-hours to conserve energy. Even with the device deactivated, the magnetic field will still be present inside the chamber.

Personnel responsible for the MRI should never allow anything metallic that can inflict irreparable harm inside the chamber. For this reason, an MRI room only contains few medical instruments, if any, apart from the MRI machine. They should also ask patients to remove any metallic items, like phones or keys, before entering.

Sometimes, a patient may need sedation before undergoing the procedure. The slightest twitch of the body can result in blurry images, and repeating the process isn’t advisable. Patients should tell their doctors about any preexisting conditions to help determine if sedation would be necessary.

Claustrophobia among patients used to be a problem, but today’s MRI machines have adopted an open design. Some hospitals and clinics even allow patients or guardians to accompany the patient inside the chamber. However, when anesthesia is involved, only the patient should remain inside.

For mothers actively breastfeeding their young, it’s recommended to pump breastmilk into a bottle or container before the procedure. The contrast agent injected into the part of the body that requires MRI may remain in the system for 24 hours. 


Despite their well-known risks, MRI machines are generally safe. When researchers from Harvard Medical School studied over 360,000 MRI exams between 2006 and 2012, MRI-related incidents accounted for less than one percent. Among these cases, most didn’t result in long-term harm. 

With the introduction of new technologies, they’ll become safer and produce more defined images. Patient comfort and digital imaging systems are among the top priorities for these improvements. Painting a clearer picture of an abnormality in the body can mean a great deal when saving lives, especially as cures for diseases such as cancer are still in the works. 

Ask your physician if MRI is right for you, as well as the things to expect in the procedure. You could also look into private MRI scans where you can go without a referral.