Magnetic Resonance Imaging (MRI) uses a powerful magnetic field and radio waves to generate detailed images of the body’s internal structures, offering a clear look at soft tissues like the brain. Proper patient preparation, especially concerning attire, is essential for both safety and diagnostic clarity. Since the process relies on a strong magnetic field, all metallic or magnetic items must be excluded from the scanning environment to ensure the procedure is performed effectively and without risk.
The Foundation of Safety: Why Metal Must Be Removed
The core principle of an MRI machine involves a superconducting magnet that produces a static magnetic field many thousands of times stronger than the Earth’s natural field. This powerful field is constantly active and exerts a significant force on any ferromagnetic material. Unsecured ferromagnetic objects can be pulled into the scanner bore at high velocity, creating a hazardous phenomenon known as the projectile or missile effect.
Beyond the physical danger, metal objects compromise the image quality by interfering with the magnetic and radiofrequency signals used to create the scan. This interference results in dark, distorted areas on the image called artifacts, which can completely obscure the brain region the radiologist needs to examine. Furthermore, the radiofrequency waves used by the machine can induce electrical currents in conductive materials, causing them to heat up rapidly and potentially lead to thermal burns on the skin.
Essential Clothing Guidelines for Comfort and Safety
If the imaging facility permits patients to wear their own clothes during a brain scan, the preferred choice is attire that is loose-fitting and entirely free of metal components. The best materials for an MRI are natural fibers, specifically 100% cotton or linen, as these are non-conductive and will not interact with the magnetic field. These materials are also breathable, which helps keep the patient comfortable while lying still inside the scanner for the duration of the exam.
Acceptable items include simple cotton T-shirts, non-metallic sports bras, and drawstring sweatpants or shorts that contain no metal in the elastic or drawstring tips. Remaining motionless is required for a clear scan, so maximizing comfort is important. It is advisable to choose older, well-worn garments for a scan, as newer or specialized clothing may contain unlisted metallic elements.
Hidden Hazards and Mandatory Removals
A thorough removal of all jewelry and accessories is mandatory, especially for a brain scan, as items near the head and neck are most likely to cause image distortion. This includes all earrings, necklaces, rings, watches, and hair accessories such as metal hairpins, clips, or hair ties. Eyeglasses must be taken off because the frame and hinge screws are typically made of metal that will interfere with the scan.
The risk extends to materials embedded within clothing and cosmetics that are not immediately obvious. Many athletic or “tech” garments, including compression wear, use invisible metallic microfibers, often silver or copper, for anti-odor or anti-static properties. These embedded fibers are highly conductive and have been documented to cause severe thermal burns during an MRI. Patients must also remove all clothing items containing metallic fasteners, such as zippers, snaps, hooks, metal buttons, and underwire bras, as these can heat up or shift in the field.
Certain cosmetics are also a concern, particularly for a head scan, because they can contain trace amounts of metallic oxides. Mascara and eyeliner often contain iron oxides, which can cause image artifacts or a slight heating sensation around the eyes. Furthermore, older tattoos or permanent makeup done with inks containing metallic pigments can heat up or cause localized image disruption. Medicated patches must also be removed, as the backing often contains metallic foil that can heat and cause skin burns.
Preparation Logistics: Gowns, Lockers, and Permanent Items
Despite arriving in metal-free clothing, most imaging centers ask patients to change into a facility-provided gown or scrubs to eliminate any uncertainty about hidden metal. This is particularly common for a brain MRI, where image quality is sensitive to metallic interference near the head and upper body. The facility will provide a secure locker or changing area for all personal belongings, including wallets, phones, and any items of clothing that must be removed.
Patients with non-removable metallic items, such as surgical implants, should inform the technologist immediately during the safety screening. Most modern surgical hardware is made from non-ferrous materials like titanium, which is considered MR-safe or MR-conditional. However, even non-ferromagnetic metal can cause image distortion, and the technician must verify the specific device’s safety credentials and adjust the scanning protocol accordingly. Non-removable body piercings and dental work, such as fillings or permanent retainers, should also be disclosed, as their proximity to the scan area can affect image clarity.