Imaging tests have different uses

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November 18, 2019 - 10:08 AM

Dear Dr. Roach: Could you please explain in layman terms the difference between an X-ray, CT scan, MRI and PET scan? — C.D.B.

Answer: All four of these tests provide images of the body, which your doctor can use to evaluate symptoms or search for a specific anatomical condition. Some conditions, such as depression, have no visible changes on any kind of commonly used imaging, but that doesn’t mean they aren’t real.

X-rays are high-energy electromagnetic waves that can travel through the body and are absorbed differently by different structures. X-rays do not travel well through bones, so X-rays are very good at seeing changes in bones due to contrast with soft tissues. They are not as useful for soft tissues, which have little contrast with each other.

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