PET/CT combines two imaging technologies to provide information about the location and metabolism of cancer cells to aid in diagnosis and treatment. PET, or Positron Emission Tomography, detects the metabolic signals given off by cancer cells growing in the body.


PET is a specialized radiology procedure used to examine various body tissues to identify certain conditions. PET may also be used to follow the progress of the treatment of certain conditions. While PET is most commonly used in the fields of neurology, oncology, and cardiology, applications in other fields are currently being studied.

PET is a type of nuclear medicine procedure. This means that a tiny amount of a radioactive substance, called a radionuclide (radiopharmaceutical or radioactive tracer), is used during the procedure to assist in the examination of the tissue under study. Specifically, PET studies evaluate the metabolism of a particular organ or tissue, so that information about the physiology (functionality) and anatomy (structure) of the organ or tissue is evaluated, as well as its biochemical properties. Thus, PET may detect biochemical changes in an organ or tissue that can identify the onset of a disease process before anatomical changes related to the disease can be seen with other imaging processes, such as computed tomography (CT).

The precise location of the cancerous cells, known as lesions or tumors, are then located with CT technology.

A CT scan directs a series of x-ray pulses through the body.  Each x-ray pulse lasts only a fraction of a second and represents a “slice” of the organ or area being studied.  The slices or pictures are recorded on a computer and can be saved for further study.

Nuclear medicine, or radionuclide, diagnostic imaging procedures are noninvasive and, with the exception of intravenous injections, are usually painless medical tests that help physicians diagnose and evaluate medical conditions. These imaging scans use radioactive materials called radiopharmaceuticals or radiotracers.

Depending on the type of nuclear medicine exam, the radiotracer is either injected into the body, swallowed or inhaled as a gas and eventually accumulates in the organ or area of the body being examined. Radioactive emissions from the radiotracer are detected by a special camera or imaging device that produces pictures and detailed molecular information.

Diagnostic Imaging Services performs PET/CT scans for these common medical reasons:

  • Differentiate malignant from non-malignant disease (diagnosis)
  • Determine whether a cancer has spread in the body (staging)
  • Assess the effectiveness of a treatment plan, such as cancer therapy (response to therapy)
  • Determine if a cancer has returned after treatment (restaging)