What is a PET-CT Scan?

Posted on: 08/06/2015

Perhaps you have heard of a PET scan, and perhaps you have heard of a CT scan, but do you know about PET-CT scans? An integrated PET-CT scan is a combination of a PET scan and a CT scan, which together create a more complete image to diagnose with. So, to understand what a PET-CT scan provides, we must first assess each scan separately.

PET Scan

Positron emission tomography (PET) scans create images of the organs and tissues inside the body. In order for the scanner to pick up the images, a fluid is injected into the bloodstream that radiates positrons. The scanner picks up the location of the positrons and creates an image that is then used to diagnose the patient. Since harmful cells in the body, like cancer cells, tend to consume more energy than healthy cells, more of the injected substance collects there. The created image reflects that, with visual emphasis where the majority of the fluid collects.

PET scans are useful for:
• Determining whether a tumor is benign or malignant
• Surveying the spread of a cancer
• Determine what heart tissue is still alive (following a heart attack)
• Predicting the success of certain surgeries
• Detecting brain diseases like Alzheimer’s

CT Scan

Like a PET scan, a computed tomography (CT) scan also creates images of the organs and tissues inside the body. However, it relies strictly on x-rays, without the help of a fluid. Using x-rays taken from several different angles, CT scans create images of the body’s organs that are much more detailed.

CT scans are useful for:
• Evaluating acute injuries to the head, abdomen, spine and pelvis
• Determining the size and location of tumors
• Detecting kidney stones
• Diagnosing appendicitis
• Special studies of blood vessels


As it turns out, these two distinct scans complement each other when combined. Run at the same time by the same machine, a PET-CT scan has the benefit of seeing any abnormal activity via the PET scan alongside the help of the CT scan’s precise imaging. Before, PET scans were less precise and localized. Alone, a CT scan could locate a tumor, but without the help of a PET scan, it would be more difficult determine whether it is benign or malignant. Since being brought together, the PET-CT scan has revolutionized medical diagnosis.

A PET-CT scan is helpful for:
• Detecting cancer and assessing its stage
• Determining the most affective cancer treatment
• Locating the best area for a biopsy
• Evaluating the effectiveness of cancer treatments

Seattle Diagnostic Imaging Services

Via Radiology provides radiology and diagnostic imaging procedures including bone density tests, mammograms, ultrasound exams, MRI exams, CT scans and other imaging modalities. Contact us online for more information.

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