Magnetic resonance imaging (MRI) is a test that uses powerful magnets, radio waves, and a computer to make detailed pictures inside your body.
Your doctor can use this test to diagnose you or to see how well you've responded to treatment. Unlike X-rays and CT scans, an MRI doesn't use radiation.
Why Would You Get an MRI?
An MRI helps a doctor diagnose a disease or injury, and it can monitor how well you’re doing with a treatment. MRIs can be done on different parts of your body.
An MRI of the brain and spinal cord looks for:
Blood vessel damage
Spinal cord injuries
An MRI of the heart and blood vessels looks for:
Blocked blood vessels
Damage caused by a heart attack
Problems with the structure of the heart
An MRI of the bones and joints looks for:
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Damage to joints
Disc problems in the spine
MRI can also be done to check the health of these organs:
A special kind of MRI called a functional MRI (fMRI) maps brain activity.
This test looks at blood flow in your brain to see which areas become active when you do certain tasks. An fMRI can detect brain problems, such as the effects of a stroke, or for brain mapping if you need brain surgery for epilepsy or tumors. Your doctor can use this test to plan your treatment.
How Do I Prepare for an MRI?
Before your MRI, let your doctor know if you:
Have any health problems, such as kidney or liver disease
Recently had surgery
Have any allergies to food or medicine, or if you have asthma
Are pregnant, or might be pregnant
No metal is allowed in the MRI room, because the magnetic field in the machine can attract metal. Tell your doctor whether you have any metal-based devices that might cause problems during the test. These can include:
Artificial heart valves
Fillings and other dental work
Implanted nerve stimulator
Metal fragments, such as a bullet or shrapnel
Metal joints or limbs
Pacemaker or implantable cardioverter-defibrillator (ICD)
Pins or screws