Positron emission tomography is a nuclear medicine imaging technique that measures metabolic activity by detecting gamma rays emitted from injected radiotracers. It can be combined with CT or MRI for anatomical localisation.
Technique
A radiolabelled compound, often fluorodeoxyglucose, is administered intravenously and taken up by metabolically active tissues. Detectors surrounding the patient record emissions, and computers reconstruct three-dimensional images of tracer distribution.
- Highlights areas of increased or decreased metabolic activity
- Often performed as PET-CT or PET-MRI for combined structural and functional data
- Involves exposure to ionising radiation from the tracer
- Requires time for tracer uptake before scanning
Ophthalmic and Neurological Uses
In relation to vision, PET is mainly used in oncological and neurological contexts, such as staging orbital or ocular tumours and investigating certain brain disorders. It can help differentiate active disease from scar tissue.
- Assists in detecting metastases or systemic involvement
- May contribute to planning radiotherapy or surgery
- Less commonly used solely for primary eye conditions
- Results are interpreted by nuclear medicine specialists with clinical correlation
