Understanding your PET scan name

FDG stands for fluorodeoxyglucose. It is similar to glucose, a sugar used for energy, and is usually labelled with fluorine-18. The scan follows how tissues take it up.

FDG is used for many cancers to assess their extent or response to treatment. Infection, inflammation and normal active tissues can also take it up, while some cancers show little uptake. Your specialist interprets the pattern alongside other information.

PSMA stands for prostate-specific membrane antigen, a protein found in large amounts on many prostate cancer cells. Tracers commonly use gallium-68 or fluorine-18 to produce the imaging signal.

The scan helps locate and assess prostate cancer in selected situations. It can also help assess suitability for PSMA treatment. Normal organs and some non-cancer findings can show uptake, so the scan needs specialist interpretation.

DOTA stands for dodecanetetraacetic acid, the part of these tracers that holds the radioactive label. The targeting part attaches to somatostatin receptors, which are docking sites found on many neuroendocrine tumours. These tumours develop from cells that can make hormones. You may see names such as DOTATATE, DOTATOC or DOTANOC on the request.

It helps locate suitable tumours and assess whether peptide receptor radionuclide therapy (PRRT), a treatment that delivers radiation to cells with these receptors, may be useful. Not all neuroendocrine cancers have enough receptors, and another type of scan may sometimes be needed.

DOPA stands for dihydroxyphenylalanine, an amino acid involved in making chemical messengers in the body. The scan uses its fluorine-18 labelled form, fluorodihydroxyphenylalanine (FDOPA), also called fluorodopa. It follows how tissues take up and process this tracer.

It is used for selected neuroendocrine tumours and some brain-tumour questions. Its preparation depends on the reason for the scan. DOPA and DOTA are different scans despite their similar names.

FAPI stands for fibroblast activation protein inhibitor. It looks for activated support cells, often around tumours, using a tracer commonly labelled with gallium-68 or fluorine-18.

This is an evolving specialist approach. Healing, scarring and inflammation can also show uptake. Your team should explain what it adds in your situation; it is not a routine replacement for every other PET scan.

Fluoroestradiol (FES) PET helps assess oestrogen receptors, which are docking sites for the hormone oestrogen, in selected breast-cancer situations. It complements other assessment and does not replace a biopsy when one is needed. FET (fluoroethyltyrosine) and MET (methionine) are amino-acid tracers used for selected brain-tumour questions alongside magnetic resonance imaging (MRI).

MIBG stands for metaiodobenzylguanidine. Its handling resembles that of noradrenaline, a chemical used by certain nerve and hormone-producing cells. MIBG imaging usually uses iodine-123 and a gamma camera, which detects radiation from the tracer, sometimes with single-photon emission computed tomography (SPECT). This is a different camera technique from PET.

An isotope is a form of an element. Some isotopes release radiation as they change. In many nuclear medicine medicines, one part helps the medicine reach a target and the radioactive isotope supplies the imaging signal or treatment radiation.

The number in fluorine-18 or lutetium-177 identifies the isotope. It is not a cancer stage or your personal dose. Radioactive iodine works through thyroid cells’ natural ability to take up iodine, without needing a separate targeting molecule.

Imaging medicines give off signals that a camera detects. Treatment medicines deliver radiation that damages cells in tissues that take them up. Some treatment medicines also produce signals that allow imaging afterwards.

PET and other nuclear medicine scans use cameras that detect different signals. An image taken after treatment is not necessarily another PET scan.

Half-life is the time taken for radioactivity to reduce by half through decay. It falls gradually rather than switching off. Your body also clears some medicines, while the beads used in liver radioembolisation remain in place as their radioactivity decays.

Your team considers the exact medicine, amount given, how it leaves your body and your household when planning precautions. Half-life alone cannot tell you when close contact or other activities are safe. Use the dates and times in your discharge advice.