positron emission tomography
POZ-ih-tron ih-MISH-un toh-MOG-ruh-fee
ˈpɒzɪtrɒn ɪˈmɪʃən toʊˈmɒɡrəfiːListen
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Syllable breakdown
Dictionary meaning
a nuclear medicine functional imaging technique that uses radioactive tracers to detect gamma rays emitted by positrons — anti-matter counterparts of electrons — to produce three-dimensional maps of metabolic and biochemical processes in the body; in PET scanning, a metabolically active radiopharmaceutical tracer such as fluorodeoxyglucose (FDG) labelled with a positron-emitting radionuclide (typically fluorine-18) is injected into the patient; tissues with high metabolic activity — such as cancer cells, active brain regions, or inflamed tissue — take up the tracer preferentially; as the radionuclide decays it emits positrons that collide with nearby electrons to produce pairs of gamma rays detected by the scanner; PET is most widely used in oncology to detect and stage cancers and assess treatment response, and in neurology to study brain function and diagnose conditions such as Alzheimer's disease; it is usually combined with CT or MRI to provide simultaneous anatomical and functional information (PET/CT, PET/MRI)
Examples
- The oncologist ordered a PET scan to assess whether the lymphoma had responded to chemotherapy.
- Positron emission tomography with FDG tracer revealed hypermetabolic activity in the mediastinal nodes, indicating active disease.
Synonyms: PET scan, PET imaging, PET/CT
Pronunciation tips
Positron is often mispronounced; it rhymes with 'proton' not 'piston'. The abbreviation PET is used universally in clinical settings.
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