July 01, 2020

Picture this

X-rays, MRI, CT scans and PET scans

Imaging tests are common, but having your body scanned in a tube can seem more like science fiction than medical science. Learn about the ways health professionals view the inside of your body detect, diagnose, treat or monitor disease.

Magnetic resonance imaging

Your doctor just told you that you need an MRI. You wonder why a less expensive CT scan wouldn't work. In fact, you're not quite sure what the difference is between a CT scan and an MRI.

Imaging tests are common, but having your body scanned in a tube can seem more like science fiction than medical science. Read on to learn more about the ways health professionals view the inside of your body, including with X-rays, computerized tomography (CT) scans, magnetic resonance imaging (MRI) and positron emission tomography (PET) scans.

The big picture

Various imaging tests work in different ways, and certain tests are better suited to detect different types of illnesses or conditions. However, they have many commonalities:

  • Contrast agents — such as gadolinium, iodine or barium — may be administered via injection, drink or enema to highlight certain areas.
  • You're instructed not to move and sometimes to hold your breath so that the image doesn't blur.
  • MRI, PET scans and CT scans are performed so that cross-sectional images of your body, or "slices" — like a piece of bread — can be viewed from multiple angles and even compiled into a 3D image.
  • X-rays, CT scans and PET scans expose you to variable but still relatively low amounts of radiation

X-ray

An X-ray is a quick, common and comparatively inexpensive test that is particularly good at providing images of: