What is a PET Scan?

By HealthPriceCompare - May 8, 2023

A PET scan is the combination of PET(Positron Emission Tomography) and CT (Computed Tomography) scans. By using radiation to show activity in the body on a cellular level, it can help detect health issues and conditions at the functional level by creating images of the body's biological processes. A PET scan is a test that can show multidimensional, color images of the inside workings of the human body.

PET scans help a doctor diagnose certain health conditions, plan treatment, find out how an existing condition is developing, or check the effectiveness of a treatment. Doctors commonly use PET scans for people who are undergoing cancer treatment and those who may have neurological or radiological problems. While an MRI or CT scan shows how part of the body looks, a PET scan helps reveal how it is functioning.

Why PET Scans

PET scans are used by healthcare providers to investigate a number of diseases and conditions including:

Heart Disease - PET scans help detect which parts of the heart have become damaged or scarred, and identify circulation problems in the working of the heart. This information helps doctors determine the proper course of treatment.

Epilepsy - By revealing which part of the brain is being affected which in turn helps doctors decide on the most suitable treatment.

Alzheimer's Disease - By measuring the uptake of sugar in specific parts of the brain, it can identify affected brain cells that tend to have reduced use of glucose compared with healthy cells.

Cancer - In addition to detecting a recurring tumor sooner than other techniques, PET scans can reveal the presence and stage of a cancer, show whether and where it has spread, determine how well chemotherapy is working and help doctors decide on treatment.

How PET Scans Work

PET scans are typically a 45-to 60-minute process that uses radioactive tracers to screen for evidence of cancers, heart or brain abnormalities, or other conditions. Before the scan, the patient is injected with a small amount of radioactive sugar called fluorodeoxyglucose-18. The cells of the body, such as cancer cells, that use more energy pick up more of the tracer and the machine then detects where the radioactive tracer is in the body. This will show up on images that a computer reconstructs.

These cells display as "hot spots" or "cold spots". Active areas, or "hot spots", are brighter on the PET scan images. Less active areas, or "cold spots" are where cells use less energy and are correspondingly less bright.

Your healthcare provider may perform a PET scan and CT scan at the same time (PET-CT). A computer then combines the PET and CT images to produce 3D images that allow for a more accurate diagnosis. Some hospitals now use a hybrid PET/MRI scan that creates extremely high-contrast images. Providers mainly use this type of scan for diagnosing and monitoring cancers of the soft tissues (brain, head and neck, liver and pelvis). A radiologist will then examine the image that the computer produces and report the findings to a doctor.

PET-Scan and CT-Scan Differences

CT scans are more adept at providing images of structures within your body, whereas PET scans can capture processes. If a physician wants a clear image of your bones or soft tissue structures, a CT scan is the preferred imaging study. However, if your physician needs to examine organ or tissue functions or detect an early-stage disease that doesn't appear on other imagining studies, a PET scan would be ordered.