An MRI (magnetic resonance imaging) scan is a test that creates clear images of the structures inside your body using a large magnet, radio waves and a computer. Healthcare providers use MRIs to evaluate, diagnose and monitor several different medical conditions.
An MRI (magnetic resonance imaging) scan is a painless test that produces very clear images of the organs and structures inside your body. MRI uses a large magnet, radio waves and a computer to produce these detailed images. It doesn’t use X-rays (radiation).
Because MRI doesn’t use X-rays or other radiation, it’s the imaging test of choice when people will need frequent imaging for diagnosis or treatment monitoring, especially of their brain.
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An open (or “open bore”) MRI refers to the type of machine that takes the images. Typically, an open MRI machine has two flat magnets positioned over and under you with a large space between them for you to lie. This allows for open space on two sides and alleviates much of the claustrophobia many people experience with closed-bore MRI machines.
However, open MRIs don’t take as clear images as closed-bore MRI machines. Closed-bore MRI machines have a ring of magnets that forms an open hole or tube in the middle where you’d lie to get the images. Closed-bore MRIs are narrow with tight head-to-ceiling space. This can cause anxiety and discomfort for some people, but these MRI machines take the best quality images.
If you’re nervous about your MRI scan or have a fear of closed spaces, talk to your healthcare provider. If needed, your provider will discuss options for sedatives (medicines to make you feel relaxed) or even anesthesia if necessary.
Some MRI exams use an injection of contrast material. The contrast agent contains gadolinium, which is a rare earth metal. When this substance is present in your body, it alters the magnetic properties of nearby water molecules, which enhances the quality of the images. This improves the sensitivity and specificity of the diagnostic images.
Contrast material enhances the visibility of the following:
If your MRI requires a contrast material, a healthcare provider will insert an intravenous catheter (IV line) into a vein in your hand or arm. They’ll use this IV to inject the contrast material.
Contrast materials are safe drugs. Side effects ranging from mild to severe do occur, but severe reactions are very rare.
Magnetic resonance imaging (MRI) uses magnets, radio waves and a computer to create images of the inside of your body, whereas computed tomography (CT) uses X-rays and computers.
Healthcare providers often prefer to use MRI scans instead of CT scans to look at the non-bony parts or soft tissues inside your body. MRI scans are also safer since they don’t use the damaging ionizing radiation of X-rays.
MRI scans also take much clearer pictures of your brain, spinal cord, nerves, muscles, ligaments and tendons than regular X-rays and CT scans.
However, not everyone can undergo an MRI. The magnetic field of MRI can displace metal implants or affect the function of devices such as pacemakers and insulin pumps. If this is the case, a CT scan is the next best option.
MRI scanning is usually more expensive than X-ray imaging or CT scanning.
Magnetic resonance imaging (MRI) produces detailed images of the inside of your body. Healthcare providers can “look at” and evaluate several different structures inside your body using MRI, including:
Healthcare providers use magnetic resonance imaging (MRI) to help diagnose or monitor the treatment for many different conditions. There are also different types of MRIs based on which area of your body your provider wants to examine.
Brain and spinal cord MRIs can help evaluate and diagnose the following conditions:
Providers use cardiac (heart) MRIs for several reasons, including:
Body MRIs can evaluate structures and diagnose several conditions, including:
MRIs of bones and joints can help evaluate:
An MRI scan is generally safe and poses almost no risk to the average person when appropriate safety guidelines are followed.
The strong magnetic field the MRI machines emit is not harmful to you, but it may cause implanted medical devices to malfunction or distort the images.
There’s a very slight risk of an allergic reaction if your MRI requires the use of contrast material. These reactions are usually mild and controllable by medication. If you have an allergic reaction, a healthcare provider will be available for immediate assistance.
Healthcare providers generally don’t perform gadolinium contrast-enhanced MRIs on pregnant people due to unknown risks to the developing baby unless it’s absolutely necessary.
In most cases, an MRI exam is safe for people with metal implants, except for a few types. Unless the device you have is certified as MRI safe, you might not be able to have an MRI. These devices may include:
If your healthcare provider recommends an MRI scan, they’ll ask detailed questions about your medical history and any medical devices or implants you may have in or on your body.
A radiologist or a radiology technologist will perform your MRI. A radiologist is a medical doctor who performs and interprets imaging tests to diagnose conditions. A radiology technologist is a healthcare provider who’s specially trained and certified to perform an MRI scan.
Magnetic resonance imaging (MRI) works by passing an electric current through coiled wires to create a temporary magnetic field in your body. A transmitter/receiver in the machine then sends and receives radio waves. The computer then uses these signals to make digital images of the scanned area of your body.
The magnetic resonance imaging (MRI) scanner uses strong magnets and radio wave signals that can cause heating or possible movement of some metal objects in your body. This could result in health and safety issues. It could also cause some implanted electronic medical devices to malfunction.
If you have metal-containing objects or implanted medical devices in your body, your healthcare provider needs to know about them before your MRI scan. Certain implanted objects may require additional scheduling arrangements and special instructions. Other items don’t require special instructions but may require an X-ray to check on the exact location of the object before your exam.
Please tell your provider and MRI technologist if you have any of the following:
You won’t be able to wear the following devices during your MRI. Please coordinate your MRI appointment with the day you need to change your patch or device.
In addition, tell your provider if you:
Leave all jewelry and other accessories at home or remove them before your MRI scan. Metal and electronic items aren’t allowed in the exam room because they can interfere with the magnetic field of the MRI unit, cause burns or become harmful projectiles. These items include:
Depending on the type of exam and the equipment used, the entire exam usually takes 30 to 50 minutes to complete. Your healthcare provider will be able to give you a more exact time range based on the specific reason for your scan.
Most MRI exams are painless, but some people find it uncomfortable to remain still for 30 minutes or longer. Others may experience anxiety from the closed-in space while in the MRI machine. The machine can also be noisy.
The general steps of an MRI scan and what to expect include:
In some cases, your MRI may require contrast. If this applies to you, a provider will give you an IV injection of contrast material before you undergo the MRI. The IV needle may cause some discomfort but this won’t last long. You may have some bruising afterward. Some people experience a temporary metallic taste in their mouth after the contrast injection.
If you have claustrophobia, your provider may recommend a sedative drug so you feel more relaxed during the exam or even anesthesia.
On very rare occasions, some people who have contrast material for their MRI experience side effects, including:
It’s very rare to experience hives, itchy eyes or other signs of an allergic reaction to the contrast material. If you have allergic symptoms, tell the technologist. A healthcare provider will be available to provide immediate medical care.
Nephrogenic systemic fibrosis (NSF), which causes thickening of your skin, organs and other tissues, is a rare complication in people with kidney disease that undergo an MRI with contrast material. Because of this, people with severe kidney disease may not be able to have gadolinium-based contrast material for their MRI.
There’s evidence that tiny traces of gadolinium may stay in different organs of your body after contrast-enhanced MRI. While there are no known negative effects from this, your provider may take gadolinium retention into account when selecting a contrast agent.
If you didn’t have a sedative drug for the MRI scan, no recovery period is necessary. You can go home and resume your normal activities. If you had sedative drugs for the exam, you’ll need to recover from the effects of them before you can go home. You may need to have someone else drive you home.
After your MRI scan, a radiologist will analyze the images. The radiologist will send a signed report to your primary healthcare provider, who will share the results with you. You may need a follow-up exam. If so, your provider will explain why.
A note from Cleveland Clinic
Magnetic resonance imaging (MRI) is a very useful and generally safe imaging test that healthcare providers use for a variety of reasons. If you need an MRI scan and are worried about the exam or have questions about it, don’t be afraid to ask your healthcare provider. They’re available to help and support you.
Last reviewed by a Cleveland Clinic medical professional on 05/09/2022.
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