James Bond’s MRI Mistake

Having recently watched the current Bond film, “Die Another Day,” I realized how easily an oversight on a writer’s part could help spark safety issues in dangerous settings.

During a fight scene that takes place in an MRI suite between James Bond and the character he believes is his nemesis, Bond uses the magnet to his advantage by turning it on and off at the most opportune times. If that had been a real-life situation Bond would have died, because the MRI industry does not employ technology that allows this type of magnetic field control.

Currently magnetic resonance imagers use either a permanent magnet or a superconducting magnet, neither of which can be turned on and off easily. The permanent magnet, like its name implies, is permanent. Much like the magnets found on your refrigerator, it is not adjustable. The magnetic field is always there.

A superconducting magnet is a type of electromagnet that is chilled to extremely low temperatures, charged to strength and is virtually everlasting. To turn this magnet on, it is “ramped up” to a desired strength over the course of hours. To remove the magnetic field, the magnet is “ramped down,” also over a matter of hours. The ramping process is done by technical or engineering personnel and specific accessory equipment. There is, however, an emergency “off” button that vents the cryogens — usually liquid helium used to cool the magnet — and causes an instant loss of field. This event is called a “quench” and is extremely harmful to the coils. If James Bond had quenched the magnet, a loud pop would have been heard indicating the “burst disk” had ruptured, the “boiling off” of the liquid helium would have created a wonderful rushing sound and a cloud of gaseous helium would have been apparent. The writers could have used a quench for visual effect but instead choose to have their hero accomplish impossible feats with imaginary medical equipment. Luckily the audience most likely will not realize the error, and let’s hope they will not think that MRIs are off when not in use.

The most important safety factor in dealing with an MRI is realizing that the field is always active. Technicians must use nonferrous tools when repairing it, and operators must use nonmagnetic equipment such as oxygen tanks, syringes and regulators. In the film, many of these devices are seen flying into the bore of the magnet when Bond energized it. In reality these items would have been “MRI-safe” and would not have moved at all.

Basically an MRI suite consists of the magnet room containing the magnet, a control room where the operator controls the radio frequency (RF) pulsing, filming and data reconstruction. Usually, a separate computer room houses RF generators, compressors, chillers and the main central processing units (CPUs).

The MRI works by combining magnetic and radio waves to create detailed images of the tissues of the body. The magnetic field created by the MRI machine is used to prepare the body to emit radio “signals.” The magnetic field causes nuclei in hydrogen atoms in the body to line up; then RF waves are aimed at the nuclei. If the frequency of the RF waves equals that of the atom, a resonance condition results. This condition allows the nuclei to absorb the energy of the RF waves. When the RF waves stop, the nuclei will return to their original orientation and emit energy in the form of very weak radio signals. The strengths and deterioration of the radio waves produced by the nuclei are detected and converted into the image.

When the RF pulses are emitted, they create a loud clanging noise. This noise is what is commonly mistaken for the magnet coming on. This misconception is what causes MRI accidents. Mop buckets, wrenches and medical equipment have ended up in the bore of MRI magnets because “I thought the magnet was off.”

MRI safety classes should be given annually to all personnel of any facility that has a magnetic resonance imager. Security personnel, housekeeping, nurses and technical personel all have the potential to come in contact with an MRI magnet and should be prepared for the magnet’s pull.

Glen L. Wolfe, CBET, CET, is a biomedical technician III in Biomedical Engineering & Support Services at LaGrange (Ill.) Memorial Hospital. His e-mail address is gw1966@hotmail.com.