Radiology and Imaging
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Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body.
Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily realigns hydrogen atoms in your body. Radio waves cause these aligned atoms to produce very faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread.
Watch a video about MRI:
Why It's Done
MRI is a noninvasive way for your doctor to examine your organs, tissues and skeletal system. It produces high-resolution images of the inside of the body that help diagnose a variety of problems.
MRI of the Brain and Spinal Cord
MRI is the most frequently used imaging test of the brain and spinal cord. It's often performed to help diagnose:
- Aneurysms of cerebral vessels
- Disorders of the eye and inner ear
- Multiple sclerosis
- Spinal cord injuries
- Brain injury from trauma
MRI of the Heart and Blood Vessels
MRI that focuses on the heart or blood vessels can assess:
- The size and function of the heart's chambers
- Thickness and movement of the walls of the heart
- The extent of damage caused by heart attack or heart disease
- Structural problems in the aorta, such as aneurysms or dissections
- Inflammation or blockages in the blood vessels
MRI of Other Internal Organs
MRI may be used to check for tumors or other abnormalities of many organs in the body, including the:
- Liver and bile ducts
MRI of Bones and Joints
MRI may be used to help evaluate:
- Joint abnormalities caused by traumatic or repetitive injuries, such as torn cartilage or ligaments
- Disk abnormalities in the spine
- Bone infections
- Tumors of the bones and soft tissues
MRI of the BreastsMRI may be used in addition to mammography to detect breast cancer, particularly in women who have dense breast tissue or who may be at high risk of the disease.
During an MRI
The MRI machine looks like a tube that has both ends open. You will lie down on a movable table that slides into the opening of the tube. A technologist monitors you from another room, and you can talk with that person by microphone.
The MRI machine creates a strong magnetic field around you, and radio waves are directed at your body. The procedure is painless. You don't feel the magnetic field or radio waves, and there are no moving parts around you.
During the MRI scan, the internal part of the magnet produces repetitive tapping, thumping and other noises. Earplugs are provided to help block the noise. If you're worried about feeling claustrophobic inside the MRI machine, talk to your doctor beforehand. You may receive a sedative before the scan.
In some cases, a contrast material, typically gadolinium, may be injected through an intravenous (IV) line into a vein in your hand or arm. The contrast material enhances the appearance of certain details.
An MRI can last up to an hour or more. You must hold very still because movement can blur the resulting images.
After an MRIIf you did not received a sedative before the scan, you may return to your normal routine immediately.
RisksBecause MRI uses powerful magnets, the presence of metal in your body may be a safety hazard or affect a portion of the MRI image. Before having an MRI, tell the technologist if you have any metal or electronic devices in your body, such as metallic joint prostheses, artificial heart valve, implantable heart defibrillator, pacemaker, metal clips, cochlear implants, bullet, shrapnel or any other type of metal fragment.
ResultsA doctor specially trained to interpret MRIs (radiologist) will analyze the images from your scan and report the findings to your primary care provider.