What do PET scan colours mean?

PET software maps detected FDG Radiotracer activity onto a colour scale. Depending on the display settings, warmer or brighter colours may indicate more activity than cooler or darker colours. The same tissue can look different when the scale, image contrast, reconstruction, or viewing method changes. Some normal organs naturally use glucose, and inflammation or infection can also produce increased activity. The CT component helps show where a signal is located. Specialists compare the pattern, shape, intensity, anatomy, symptoms, and earlier images before deciding what a finding may represent.

Do not judge a scan from a screenshot or colour alone. Read the written report and ask the clinician to explain terms such as uptake, activity, or comparison. Bring information about recent infection, surgery, treatment, blood glucose issues, and previous imaging because these details can affect interpretation. The PET-CT Scanner page describes the equipment used to create the images.

The colour pattern itself is not an emergency signal. Follow the reporting clinician's instructions about follow-up. Seek urgent care for new severe symptoms such as difficulty breathing, fainting, sudden weakness, or uncontrolled pain, whether or not the scan shows a bright area. Contact the imaging team if you need clarification about when the report will be released.

What colour scale and display settings were used? Which findings are expected normal uptake? Is a bright area also visible on CT? Could inflammation, infection, or recent treatment explain the pattern? Do I need comparison with earlier images or another test?