Permanent jewelry, a recent fashion trend involving a clasp-less chain welded directly onto the body, raises safety questions regarding Magnetic Resonance Imaging (MRI) scans. Since these items are worn indefinitely, their safety during an MRI is a serious concern. Safety is not guaranteed and depends entirely on the metal’s composition and the jewelry’s geometry. Because MRI machines use incredibly powerful magnetic fields and radiofrequency energy, any metal near the scanner poses a potential hazard that must be evaluated before a procedure.
Understanding the MRI Safety Concern
The primary danger of metal in an MRI environment stems from the scanner’s super-conducting magnet, which is typically 30,000 to 60,000 times stronger than the Earth’s magnetic field. This powerful static field exerts a significant magnetic force on certain metals, creating a risk known as the “missile effect” or torque. Ferromagnetic objects, such as iron or steel, can be violently pulled toward the magnet, causing severe injury or damage to the scanner.
Metal also interacts with the radiofrequency (RF) pulses and gradient fields used to create images. This interaction induces electrical currents in conductive materials, causing the metal to heat up rapidly. This can lead to severe thermal burns where the jewelry contacts the patient’s skin. Even without movement or heating, the metal’s presence can cause image artifacting. These artifacts appear as distorted or blank areas, which can obscure the anatomical details the physician needs for an accurate diagnosis.
How Jewelry Material Affects MRI Safety
Jewelry metals are broadly categorized by their magnetic properties, which determine the level of risk they pose in an MRI.
Ferromagnetic Materials
These materials, including iron, nickel, and certain stainless steel alloys, pose the highest risk. They are strongly attracted to the magnet and are highly susceptible to dangerous heating. Because nickel is often used as an alloy in lower-karat gold or sterling silver, even seemingly safe jewelry may contain small ferromagnetic impurities.
Diamagnetic and Paramagnetic Materials
Diamagnetic materials, such as high-karat gold, silver, and copper, exhibit a negligible magnetic reaction and are not attracted to the magnet. Platinum is classified as paramagnetic, meaning it has a very weak attraction, but is generally considered relatively safe in terms of movement risk.
The risk of Radiofrequency (RF) heating remains, regardless of the metal’s magnetic attraction. Any conductive metal that forms a complete loop around a limb, even materials like gold or silver, can act as an antenna to the RF pulses. This can concentrate the energy and cause localized heating and burns, especially in the fine-gauge chains used for permanent jewelry. The final determination of safety always rests with the MRI technologist and the radiologist, who must weigh the material’s properties against the specific scan parameters and location.
Preparation and Protocol for Scanning
For anyone with permanent jewelry, the most important step before an MRI is to proactively inform the imaging center and the technologist. Safety protocols at nearly all facilities require the removal of all metallic items, including permanent jewelry, to eliminate any potential risk. This is a mandatory precaution because the cost of damage to the patient or the multi-million-dollar scanner far outweighs the inconvenience of removal.
Permanent jewelry is designed to be easily removed by clipping a single link, often at the jump ring, which can be done using common nail clippers. Patients should secure the piece immediately after removal to ensure it can be re-welded by their jeweler later. If a patient refuses or is unable to remove the jewelry, the scan may be canceled. In rare, life-threatening situations, the technologist may attempt to shield the area or adjust the scan parameters, though this significantly compromises image quality and safety.