MRI

Magnetic resonance imaging (MRI) uses radio waves and powerful magnets to create three-dimensional (3D) images of the inside of your body. Unlike X-rays and CT scans, MRIs don’t use ionizing radiation. This makes them a safer option for people who need frequent imaging scans. We use MRI to diagnose and monitor many conditions that affect the brain, spinal cord, nerves, lymph nodes, soft tissues, and other non-bony parts of your body.

An MRI works by creating a strong magnetic field around your body. The magnet forces hydrogen atoms (present in every cell) to align with its magnetic field.

Next, a scanner sends radio waves through your body to knock the atoms out of alignment. When the radio waves are turned off, the atoms realign with the magnetic field and release energy in the process.

Atoms in different types of tissue release different levels of energy. A sensor detects the energy and sends the data to a computer that creates 3D pictures.

Any MRI has many uses. We may use it to look for causes of unexplained symptoms such as headaches or back pain. It’s beneficial for monitoring conditions like brain tumors or cancer. Surgeons and interventional radiologists also use MRI guidance to perform certain treatments and procedures such as biopsies.

You may have an MRI with or without contrast. A contrast agent is a substance that makes certain tissues or structures appear in more detail on imaging scans. If you need an MRI with contrast, we inject the material into a vein in your arm.

Common types of MRI include:

• Abdominal and pelvic MRI: creates pictures of the bladder, liver, kidneys, spleen, and reproductive organs
• Brain MRI: evaluates the structure of the brain, brain tumors, and changes to brain tissue
• Breast MRI: provides more detailed images in people who are high risk for breast cancer, have received a recent breast cancer diagnosis, or had an abnormal mammogram
• Cardiac MRI: evaluates the size and function of the heart, as well as the tissue and blood vessels around it
• Functional MRI (fMRI): measures brain activity and blood flow when you speak, think, and move, and detects brain damage or degeneration
• MR angiography (MRA): evaluates (usually with contrast) narrowed or blocked blood vessels throughout your body
• MR enterography: evaluates the small intestine to detect problems in the digestive tract
• Musculoskeletal MRI: evaluates the joints, spine, and soft tissues around bones

We may recommend an MRI to diagnose:

• Abnormal blood vessels or aneurysms
• Cancer that has spread to lymph nodes or other areas of the body
• Damage or scarring from a stroke or heart attack
• Inflammatory diseases and infections
• Injuries to tendons, cartilage, ligaments, and muscles
• Neurological disorders such as epilepsy, multiple sclerosis, and Alzheimer’s disease
• Spinal cord injuries or degenerative diseases
• Stroke and bleeding in the brain
• Tumors anywhere in the body

MRI is a painless and noninvasive test. Radiation technologists and radiologists work together to perform and review MRI scans. The length of the scan varies depending on what type of MRI you need, but typically takes anywhere from 20 minutes to one hour.

You may have an MRI at a hospital or outpatient imaging facility. Most scans don’t require any special preparation, but for some you should stop eating or drinking several hours prior to the exam. There may also be special instructions if you need an MRI with contrast. Your care team will tell you everything you need to know.

Most MRI machines are enclosed, tube-shaped structures. Some people with claustrophobia (fear of enclosed spaces) may have anxiety about the scan. Talk to your radiology team before your MRI if you would like a sedative to help you relax. In some cases, we can use an open MRI machine that isn’t enclosed. You should also notify your care team if you’re pregnant or think you may be pregnant.

During an MRI, here’s what you can expect:

1. You remove all jewelry, watches, piercings, and other metal and electronic items from your body.
2. We ask you to put on a hospital gown, so clothing doesn’t interfere with the scan.
3. You lie down on a comfortable scanning bed attached to the MRI machine.
4. The radiation technologist may attach a coil to the area of your body being scanned. The coil helps the scanner take accurate pictures.
5. When the scan starts, the bed slowly moves inside the large magnet in the MRI scanner.
6. The technologist will be in another room but can talk to you through an intercom.
7. During the scan, you’ll hear loud knocking noises. We give you headphones before the exam starts.
8. You won’t feel anything during the scan, but it’s important to stay very still. The technologist may ask you to hold your breath for a few seconds.
9. When the scan is complete, the table you’re lying on moves out of the scanner.

There’s no downtime after an MRI. It doesn’t require anesthesia, so you can resume normal activities after the scan. You may need someone to drive you home if you have a sedative. If you have an MRI with contrast, we may ask you to remain at the hospital or imaging facility a bit longer so we can make sure you’re not experiencing any side effects from the contrast agent.

An MRI is a safe exam for most people. But some implanted devices that contain metal shouldn’t be scanned because the magnet can interfere with how they work. Tell the radiation technologist if you have any of the following medical implants:

• Artificial joint (prosthesis)
• Cochlear implant
• Pacemaker or defibrillator
• Clips or coils for aneurysms or other vascular conditions
• Neurostimulator

At Penn Medicine, we stay current on the latest advances in radiation technology to deliver accurate results and the answers you need. Our imaging program is home to renowned radiologists who are leaders in neuroradiology, breast imaging, cardiothoracic imaging, and other specialties. When you turn to us for your MRI scan, you’ll find:

• Recognized expertise: We are fully accredited in magnetic resonance imaging by the American College of Radiology. This accreditation demonstrates our commitment to exceptional care, from the training of our staff to the quality and safety of our equipment.
• Customized care: Your comfort and peace of mind are our top priorities. We offer special MRI systems that can accommodate larger people or those with claustrophobia at many of our imaging locations throughout the Greater Philadelphia, Lancaster, and Princeton areas.
• Advanced technology: Our leading-edge MRI systems use some of the strongest magnets clinically available to produce high-resolution images with incredible speed. These features mean you spend less time in the scanner and are more likely to get an accurate scan the first time, reducing the risk of a repeat MRI.