PET-MR scanner: what should you know?

PET-MR combines two imaging methods in one examination. A tracer shows areas of altered metabolic activity, while MRI uses a magnetic field and radio waves to produce detailed soft-tissue images. This can be useful when the location and character of tissue need close comparison. The equipment is different from a standard [MRI Scanner](/technology/mri-scanner/), and the appointment may involve a longer period of stillness. Tracer uptake can have non-cancer causes such as inflammation, so an active signal needs interpretation alongside your history, examination and other tests.

Tell the imaging team about metal implants, a pacemaker, medication pumps, kidney problems, diabetes, pregnancy or breastfeeding, and any difficulty with enclosed spaces. Follow instructions about food, drink, medicines and exercise. Remove jewellery and other metal objects before entering the MRI area. You may receive the tracer and, when appropriate, an MRI contrast medicine. During imaging, use the call button if you feel distressed; the team can communicate with you. Ask whether a focused study such as [Breast MRI](/treatments/diagnostics-and-imaging/breast-mri/) or a standard [MRI Scan](/treatments/diagnostics-and-staging/mri-scan/) would answer the clinical question.

Tell staff immediately about chest tightness, trouble breathing, faintness, severe discomfort or a sudden feeling of panic. After the appointment, seek urgent help for facial or throat swelling, severe breathing difficulty, collapse or chest pain. Contact the imaging service for a spreading rash, persistent vomiting or worsening pain after an injection. These symptoms concern your safety and are separate from the meaning of an image. Your referring clinician should explain the report and any follow-up rather than relying on a single scan phrase.

Find out why PET-MR was selected, how long you should expect to remain still, whether contrast is planned, and what implant checks are needed. Ask how your medicines and diabetes affect preparation, when results will arrive, and whether another scan would provide the information needed.