A Positron Emission Tomography (PET) scan is a type of imaging test. It uses a radioactive drug, sometimes called a tracer, ligand, or radiopharmaceutical, to locate and visualise disease in the body.
Techniques such as X-ray Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) are used to look at the body’s structure or anatomy. In contrast PET imaging is used to look at the body’s function or metabolism. PET imaging agents have the ability to bind to cell surface receptors or be taken up by cellular transporters, enabling visualisation of differential activity of these in diseased tissue vs normal tissue. PET scanning is normally combined with one of the anatomical imaging techniques mentioned above, as PET/CT or PET-MRI, to assist in defining the anatomical locations of PET ‘hot spots’.
The most widely used PET tracer is fluoro deoxy-glucose (FDG) which is taken up into cells as part of energy metabolism. FDG is used extensively in clinical oncology to search for metastases or to monitor response to certain therapies (1). FDG does not work well in some tumor types, like prostate and brain cancer (2).