It can view slices from the bottom axial , front coronal , or sides sagittal , depending on what your doctor needs to see. A dye contrast agent may be injected into your bloodstream to enhance certain tissues. The dye contains gadolinium, which has magnetic properties. It circulates through the blood stream and is absorbed in certain tissues, which then stand out on the scan.
MR angiogram MRA. MRI can be used to view arteries and veins. Contrast dye gadolinium injected into the bloodstream helps the computer "see" the arteries and veins. Contrast is also used to view tumors and arteriovenous malformations AVMs.
Nearly every part of the body may be studied with MRI. MRI gives very detailed pictures of soft tissues like the brain. Air and hard bone do not give an MRI signal so these areas appear black.
Bone marrow, spinal fluid, blood and soft tissues vary in intensity from black to white, depending on the amount of fat and water present in each tissue and the machine settings used for the scan.
The radiologist compares the size and distributions of these bright and dark areas to determine whether a tissue is healthy. A radiology technologist will perform the test in the MRI suite of the Radiology department of the hospital or outpatient imaging center. You will lie on a moveable bed with your head cradled on a headrest and your arms at your sides. An antenna device, called a coil, will be placed over or around the area of the body to be imaged.
It is specialized to produce the clearest picture of the area it is placed over. If the MRI scan will be used for surgical planning, the technologist may place small markers called fiducials on your forehead, face, or behind your ear. Fiducials look like lifesavers and assist the surgeon during image-guided surgery. MRI scanners are air-conditioned and well-lit. In some cases, IV injection of contrast material may be given before the images are obtained.
The IV needle may cause you some discomfort and you may experience some bruising. There is also a very small chance of skin irritation at the site of the IV tube insertion. Some patients may have a temporary metallic taste in their mouth after the contrast injection.
If you do not require sedation, no recovery period is necessary. You may resume your usual activities and normal diet immediately after the exam. On very rare occasions, a few patients experience side effects from the contrast material. These may include nausea, headache, and pain at the site of injection. It is very rare that patients experience hives, itchy eyes, or other allergic reactions to the contrast material. If you have allergic symptoms, tell the technologist.
A radiologist or other doctor will be available for immediate assistance. A radiologist, a doctor trained to supervise and interpret radiology exams, will analyze the images. The radiologist will send a signed report to your primary care or referring physician, who will share the results with you. You may need a follow-up exam. If so, your doctor will explain why. Sometimes a follow-up exam further evaluates a potential issue with more views or a special imaging technique.
It may also see if there has been any change in an issue over time. Follow-up exams are often the best way to see if treatment is working or if a problem needs attention. High-quality images depend on your ability to remain perfectly still and follow breath-holding instructions while the images are being recorded. If you are anxious, confused or in severe pain, you may find it difficult to lie still during imaging. A person who is very large may not fit into certain types of MRI machines.
There are weight limits on the scanners. Implants and other metallic objects can make it difficult to obtain clear images. Patient movement can have the same effect. A very irregular heartbeat may affect the quality of images. This is because some techniques time the imaging based on the electrical activity of the heart. Breathing may cause artifacts , or image distortions, during MRIs of the chest, abdomen and pelvis.
Bowel motion is another source of motion artifacts in abdomen and pelvic MRI studies. This is less of a problem with state-of-the art scanners and techniques.
Present data show no convincing evidence that non contrast MRI harms the fetus of a pregnant woman. However, if the need for the exam is not time sensitive your doctor may delay the exam until after delivery. MRI gadolinium contrast agents are generally avoided during pregnancy except in very specific circumstances. Your doctor will discuss the benefits and risks of any MRI procedure with you.
Doctors may perform MRI after the first trimester to assess the fetus for findings that are not fully evaluated by ultrasound. MRI may not always distinguish between cancer tissue and fluid, known as edema. An MRI exam typically costs more and may take more time than other imaging exams. Talk to your insurance provider if you have concerns about the cost of MRI.
Please type your comment or suggestion into the text box below. Note: we are unable to answer specific questions or offer individual medical advice or opinions. Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Please contact your physician with specific medical questions or for a referral to a radiologist or other physician.
To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database. This website does not provide cost information. The costs for specific medical imaging tests, treatments and procedures may vary by geographic region. Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the Radiological Society of North America RSNA and the American College of Radiology ACR , comprising physicians with expertise in several radiologic areas.
Outside links: For the convenience of our users, RadiologyInfo. Toggle navigation. What is MRI of the Body? What are some common uses of the procedure? How should I prepare for the procedure?
What does the equipment look like? How does the procedure work? How is the procedure performed? Your doctor can use the images to make a diagnosis and recommend the best treatment for your condition. An MRI uses powerful magnets, radio waves and a computer to take images of your brain. MRI images are clearer and more precise than other forms of diagnostic imaging.
When your body is placed in an MRI scanner, it enters a strong magnetic field which causes your hydrogen protons to realign. As the protons move back to their original alignment, they emit energy.
The MRI machine captures this energy to create pictures. Radio waves transmit a signal to a computer which then processes MRI images. Soft tissues refer to muscles , fat, blood vessels, nerves and other tissues in the body.
The human brain is almost 60 percent fat and around 75 percent water. Brain tissue is also made up of about billion nerve cells.
An MRI is the most sensitive imaging test for brain scans today. An MRI will help your doctor make an early diagnosis of a range of health conditions. You might get a head MRI so your doctor can check for any of the following:. By looking at MRI images, your doctor can see details of blood flow and fluids surrounding the brain, which can help determine abnormalities in the brain relating to arteries and veins. An MRI brain scan also shows brain lesions. A brain lesion appears as a dark or light spot that does not look like normal brain tissues.
Brain lesions may be present due to multiple sclerosis or as a result of an infection or a tumor. In general, a brain MRI will enable your doctor to examine blood flow and tissue health in the following brain structures.
You should not have to do too much to prepare for a head MRI. Patients are often provided with earphones to listen to music to distract them from these noises during the procedure.
For some patients, claustrophobia may be an issue as the space within the MRI can be confining. Patients with claustrophobic anxiety and children may need light sedation. Throughout the procedure, imaging technicians are able to communicate with the patient via intercom to ensure that the patient is informed and comfortable.
The MRI scan is a painless and safe scan that produces clearer images of the body and its tissues, at any angle. This is particularly useful in detecting soft tissue tumours throughout the body.
An MRI is nearly twice as sensitive as x-ray mammography in detecting breast cancer in women with a high genetic risk of the disease. It uses no radiation for scanning and therefore eliminates the health risk of x-rays that do use radiation. While an MRI scan is a relatively safe procedure as there is no damaging radiation involved, there are still several risks. If the patient is pregnant, or suspects they may be, a doctor should be informed because the effects on an unborn baby are poorly understood.
There is also the risk of patients being injured if they forget to remove pieces of metal from their body or their clothing. If sedation is required due to claustrophobia, then there are associated risks of over-medication.
If a contrast dye is used, which helps to show up some parts of the body more clearly, there is a small risk of allergic reaction. An MRI is a very expensive and time consuming investigation compared to other methods such as x-ray and CT. Some parts of the body, like bone, are better examined using simpler techniques such as an x-Ray.
An MRI may not always be able to tell the difference between some disease processes. It is also not a very good investigation for emergencies or accidents because of the long time it takes and the fact that all equipment has to be removed from the room while the machine is running.
The patient receives MRI results from the referring physician who ordered the test. The image is available almost immediately, but the time from when the image is made available to when a report is issued will vary depending on the complexity of the case. This type of MRI is designed to show the blood vessels. It is most often used to examine the arteries and veins of the head, neck, brain and heart.
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