Magnetic Resonance Imaging (MRI) uses a powerful magnetic field and radio waves to create detailed pictures of the body’s organs and tissues. The machine generates an extremely strong static magnetic field, necessitating strict safety protocols regarding metal. You cannot wear a typical bra during an MRI examination.
The Direct Answer and Safety Rationale
The primary reason standard bras are prohibited is the presence of metallic components that interact dangerously with the scanner’s magnetic field. The MRI magnet is always active, and its immense strength can turn ferromagnetic metals—such as iron, nickel, or cobalt—into dangerous projectiles. This “missile effect” accelerates metal items toward the machine, posing a risk to the patient and staff.
Metal also interferes with the scan itself, leading to image degradation. When metal alters the magnetic field locally, it creates artifacts, which are distorted areas on the resulting image. This distortion makes accurate diagnosis difficult for the radiologist, potentially requiring a repeat of the procedure.
A third concern is the risk of thermal burns caused by the radiofrequency (RF) pulses used during the scan. Metal acts as a conductor, and the RF energy induces electrical currents in metallic objects touching the skin. This causes the metal to heat up rapidly, potentially leading to burns.
Specific Components That Cause Issues
The most common metallic component in traditional undergarments is the underwire, a ferrous metal strip designed for shape and support. Even bras advertised as “wireless” may contain problematic metal parts that require removal before entering the scanner room.
Metal hooks, clasps, and adjusters are typically made of ferromagnetic alloys. These small parts can heat up and interfere with image quality, especially if the scan area is near the chest or upper torso.
Less obvious components, such as metallic threads or conductive fibers, are increasingly used in modern athletic wear. These microfibers, sometimes made from silver for anti-odor properties, can react strongly to the magnetic field and cause thermal burns. A bra must be entirely free of all metal, including concealed fibers and trace metals in elastics or trim, to be considered safe for an MRI.
Safe Alternatives and Preparation Guidelines
Due to the potential hazards, most imaging facilities provide patients with a metal-free cotton gown to wear during the scan. Changing into the facility’s attire is the safest way to ensure clothing is completely non-conductive and free of unseen metal components.
If a patient prefers to wear their own clothing, it must be loose-fitting and made entirely of cotton, linen, or other natural fibers, without any zippers, snaps, or metallic logos. Patients must also remove all personal metallic items before the exam.
It is important to remember that some cosmetics, like mascara, and transdermal patches may contain trace metallic particles that can interfere with the scan. Always communicate any specialized garments, such as surgical bras or non-removable medical devices, with the MRI staff beforehand.
Preparation Steps
- Remove all jewelry and watches.
- Remove hairpins and body piercings.
- Avoid wearing cosmetics that contain metallic particles.
- Inform staff about any transdermal patches.