Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic tool that provides highly detailed images of the body’s soft tissues and organs. The technology relies on a powerful magnetic field and radio waves to generate cross-sectional views without using ionizing radiation. Because the imaging process depends on this intense magnetic environment, patient preparation is paramount for safety and image quality. Failing to follow pre-scan instructions can lead to serious hazards or necessitate repeating the examination due to image artifacts.
Prohibited External Items
The magnetic field is always active and can attract ferromagnetic materials with extreme force. Removing all metallic accessories is necessary to prevent the projectile effect, where objects become dangerous airborne hazards. Even small items like watches, rings, earrings, and body piercings must be removed, as the magnetic pull can cause them to heat up or move violently.
Clothing presents a risk, especially garments containing hidden metallic components. This includes zippers, buttons, snaps, hooks, and underwire bras, which can all interact with the magnetic field. Specialized athletic wear or anti-microbial fabrics sometimes contain metallic threads or silver-based compounds that can heat up and cause skin burns during the scan. Patients are typically asked to change into a metal-free gown provided by the facility to eliminate these risks.
Certain cosmetics and topical products can interfere with the procedure or cause localized skin irritation. Some mascaras, eyeliners, and hair sprays contain trace metallic particles that may cause image distortion, particularly during a head or neck scan. Tattoos and permanent makeup, especially those using iron oxide-based pigments, may experience a temporary tingling or burning sensation due to heating. Disclosing all tattoos and cosmetic ink is necessary so the technologist can monitor for any discomfort.
Non-Negotiable Medical Disclosures
Disclosing all internal medical devices and metallic fragments is necessary, as these can pose severe, life-threatening risks. Devices like cardiac pacemakers and implantable cardioverter defibrillators (ICDs) are typically contraindications, meaning they cannot safely enter the magnetic environment unless certified as “MR Conditional” and scanned under strict protocol. Failure to disclose these can result in device malfunction, rapid heating, or movement within the body.
Older cerebral aneurysm clips made of ferromagnetic material represent a danger, as the magnetic force could cause them to move, potentially leading to a hemorrhage. Any metallic foreign bodies, such as shrapnel, bullet fragments, or metal shards from industrial work, must also be reported, especially if located near a delicate structure like the eye. Staff needs to know the exact type and manufacturer of internal hardware, including cochlear implants, neurostimulators, and drug pumps, to confirm compatibility with the magnetic field.
Dietary and Medication Limitations
Preparation for some MRI types involves managing what the patient consumes before the scan. Fasting is often required for scans of the abdomen or pelvis, where food and active digestion can degrade image quality. The digestive process causes peristalsis, or involuntary muscle contractions, which create motion artifacts that blur the images. Patients are typically instructed to refrain from eating solid food for four to six hours prior to the procedure.
Fasting is also required if the scan involves an intravenous contrast agent, such as Gadolinium, to reduce the risk of nausea or vomiting. Patients with kidney issues or diabetes must discuss their condition with their physician, as these factors may affect how the contrast agent is processed or necessitate adjustments to medication schedules. Patients should never stop taking prescription medication, such as for blood pressure or a chronic condition, without first consulting the prescribing physician.
Errors in Positioning and Movement
The success of an MRI scan depends on the patient’s ability to remain completely motionless during image acquisition. Even slight movement, such as a subtle shift in position or swallowing, can blur the high-resolution images, creating artifacts that make diagnosis difficult. If movement occurs, the imaging sequence must be repeated, significantly prolonging the time spent inside the scanner and potentially delaying the schedule for other patients.
Patients should not wait until they are positioned inside the machine to mention severe claustrophobia or anxiety. High anxiety is a common cause of voluntary patient motion, and addressing it beforehand allows the doctor to prescribe a mild sedative, ensuring a successful scan.
Patients must use the provided safety tools, such as ear protection to dampen the loud operational noises and the call button to communicate distress to the technologist. If a patient feels an intense sensation, such as burning or pain, they must use the call button immediately so the scan can be paused.