MRI Scan

Overview

Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging procedure that uses powerful magnets, radio waves, and a computer to create detailed pictures of organs, soft tissues, bones, and other internal structures. Unlike X-rays or CT scans, MRI does not use ionizing radiation, making it a safer option for certain patients and repeated imaging. The MRI scanner is typically a large, tube-shaped machine with a sliding table where you lie during the scan. The magnetic field temporarily aligns water molecules in your body, and radio waves cause these molecules to produce signals that are detected and converted into highly detailed images. MRI is especially valuable for examining the brain, spinal cord, joints, and internal organs. It can help detect tumors, bleeding, infections, blood vessel problems, injuries, and many other conditions. Depending on what your doctor needs to see, the scan may take anywhere from 15 minutes to over an hour. Some MRI scans require a contrast dye (usually gadolinium-based) injected into a vein to make certain tissues or blood vessels show up more clearly. MRI provides exceptional detail that often cannot be achieved with other imaging methods, making it an essential diagnostic tool in modern medicine.

Purpose

• Detect and monitor tumors, cysts, or other abnormal growths in the brain, spine, or other organs
• Evaluate injuries to joints, ligaments, tendons, and cartilage, particularly in the knee, shoulder, or hip
• Diagnose neurological conditions such as multiple sclerosis, stroke, aneurysms, or spinal cord disorders
• Assess heart and blood vessel problems, including heart defects, damage from heart attacks, or blockages
• Identify infections, inflammation, or abscesses in various parts of the body
• Examine the liver, kidneys, pancreas, and other abdominal organs for disease or damage
• Evaluate pelvic organs including the uterus, ovaries, and prostate for abnormalities
• Guide biopsies or other procedures by providing detailed images of the target area
• Monitor the progression of disease or the effectiveness of treatment over time

Preparation

• Inform your healthcare provider about all medical conditions, especially kidney disease, as this may affect whether contrast dye can be safely used
• Notify the medical team if you are pregnant or might be pregnant, as MRI safety during pregnancy requires special consideration
• Report any metal implants, devices, or objects in your body, including pacemakers, cochlear implants, metal clips, shrapnel, or joint replacements, as the strong magnetic field can affect certain metals
• Tell the staff if you have tattoos or permanent makeup, as some contain metallic particles that could cause problems
• Mention if you are claustrophobic (afraid of enclosed spaces), as your doctor may prescribe a mild sedative to help you relax
• Remove all metal objects before the scan, including jewelry, watches, hairpins, hearing aids, dentures with metal, body piercings, and clothing with metal fasteners or underwire
• Follow any specific eating or drinking instructions provided, particularly if contrast dye will be used; some facilities require fasting for a few hours beforehand
• Wear comfortable, loose-fitting clothing without metal zippers or snaps, or change into a hospital gown provided by the facility
• Leave valuables at home, including credit cards and electronic devices, as the magnetic field can damage them
• Arrange for someone to drive you home if you will receive sedation

How it's done

• You will lie down on a padded motorized table that slides into the MRI scanner; depending on which body part is being examined, you may enter the machine headfirst or feet-first
• The technologist will position you carefully and may place cushions, straps, or a coil (a device that sends and receives radio waves) around or near the area being scanned to improve image quality
• If contrast dye is needed, a small intravenous (IV) line will be inserted into a vein in your arm before or during the procedure
• You will be given earplugs or headphones to protect your hearing, as the MRI machine makes loud knocking, thumping, or buzzing noises during the scan
• The table will slide into the scanner tunnel, where you must remain very still; even small movements can blur the images and require the scan to be repeated
• The technologist will leave the room but can see, hear, and speak with you at all times through an intercom system; you will also be given a call button to press if you need assistance
• The machine will make a series of loud noises as it captures images from different angles; each sequence may last from a few seconds to several minutes
• You may be asked to hold your breath for short periods during certain sequences, especially if your chest or abdomen is being scanned
• If contrast dye is used, it will be injected through the IV line partway through the exam, and additional images will be taken afterward
• Once all the necessary images are captured, the table will slide out of the machine, any IV line will be removed, and the procedure is complete

Risks

• The MRI procedure itself is generally very safe and does not use ionizing radiation, but there are some considerations to be aware of
• The strong magnetic field can cause serious injury if metal objects are brought into the scanning room, as they can become dangerous projectiles or cause burns
• Certain implanted medical devices, such as some pacemakers, defibrillators, or cochlear implants, may malfunction or be damaged by the magnetic field, though many newer devices are MRI-compatible
• Metal fragments in the eyes or certain parts of the body can shift or cause injury during the scan
• Some people experience claustrophobia, anxiety, or panic when inside the scanner tunnel; sedation is available if needed
• The loud noises from the machine can be uncomfortable, though hearing protection is always provided
• Contrast dye reactions are uncommon but can include mild symptoms like coolness at the injection site, nausea, or headache, and very rarely, allergic reactions ranging from hives to severe anaphylaxis
• People with severe kidney disease may be at risk for a rare condition called nephrogenic systemic fibrosis (NSF) when exposed to certain gadolinium-based contrast agents, which is why kidney function is often checked beforehand
• Pregnancy during the first trimester may be a concern, and MRI is generally avoided during this period unless absolutely necessary, though no harmful effects have been proven
• Burns can occur from skin contact with the scanner bore or from looped wires or cables, which is why proper positioning and equipment setup are essential

Recovery

• If you did not receive sedation, you can typically resume normal activities immediately after the MRI scan
• If sedation was used, you will need to rest in a recovery area until the medication wears off, and you must have someone drive you home
• The IV site may be slightly sore or bruised for a day or two; applying a cold compress can help reduce any swelling
• Drink plenty of fluids after the scan if contrast dye was used, as this helps flush it from your system through your kidneys
• Most people experience no side effects, but if you notice any unusual symptoms such as hives, itching, or difficulty breathing after receiving contrast dye, contact your healthcare provider immediately
• Your MRI images will be reviewed by a radiologist (a doctor who specializes in interpreting medical images), who will prepare a detailed report for your healthcare provider
• Results are usually available within a few days to a week; your doctor will discuss the findings with you and explain what they mean for your health and any next steps
• Follow up with your healthcare provider as scheduled to discuss the results and any recommended treatment or further testing

Frequently asked questions