Both can be used to diagnose or evaluate many different medical conditions.
The two techniques can also be combined into a PET-CT scan to provide more detailed information about cancer.
This article will review the basics of PET and CT scanning, including their differences and their medical uses.
JohnnyGreig / Getty Images
JohnnyGreig / Getty Images
What Is a CT Scan?
As with X-rays, CT involves exposure to low-dose ionizing radiation.
For example, bone blocks more X-rays than fat, causing bones to appear white on CT scans.
Some CT scans involve acontrast dyedelivered orally (by mouth) intravenously (into a vein).
What Is a PET Scan?
Any abnormal changes in metabolism may suggest a medical concern.
These are indicated by different colors or degrees of brightness on a PET image.
These metabolic changes will appear as bright-colored spots on the PET scan.
Combined PET-CT scanners perform almost all PET scans today.
Together, they may be able to provide a more accurate diagnosis than the two scans performed separately.
A CT scan can cost one-half to two-thirds less.
PET scans detect functional changes in metabolism that indicate disease.
CT scans detect structural changes in bones, organs, and tissues indicative of disease or injury.
National Institute of Biomedical Imaging and Bioengineering.Computed tomography (CT).
Johns Hopkins Medicine.Computed tomography (CT scan).
National Cancer Institute.PET scan.
American Heart Association.Positron emission tomography.
National Cancer Institute.PET-CT scan.
2018 Jul;19(4):e51728.
