How Are PET Scans and MRIs Done?


Quick Answer

A PET scan uses a moving camera that records the movement of a tracer through the body, turning the recording into pictures on a computer, explains WebMD. An MRI is a test that produces very clear pictures of the human body using a large magnet, radio waves and a computer.

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Full Answer

Before conducting a positron emission tomography, or PET scan, a tracer liquid is injected into a vein, according to WebMD. The tracer is a special form of a substance, such as glucose, that collects in cells that are using a lot of energy, such as cancer cells. The tracer moves through the body, where it collects in the specific organ or tissue. The tracer gives off tiny positively charged particles, which the camera records. The recording is turned into pictures and sent to a computer for viewing. Many scans are done to make a series of pictures.

An MRI, or magnetic resonance imaging, can often detect damaged areas in the brain or spinal cord that are likely to be missed by other imaging techniques, such as a CT scan, notes WebMD. Some MRI exams require an injection of a contrast material to help identify abnormalities in certain parts of the body on the scan images. Most MRIs take 40 to 80 minutes; during that time, several dozen images may be taken.

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