Positron emission mammography (PEM) is a nuclear medicine imaging modality used to detect or characterise breast cancer.

[2][3] PEM is not recommended for routine use or for breast cancer screening, in part due to higher radiation dose compared to other modalities.

[5] Specific indications can include "high-risk patients with masses > 2 cm or aggressive malignancy and serum tumor marker elevation".

Positrons emitted by the injected 18F-FDG annihilate on interaction with electrons in tissue, leading to the emission of a pair of photons travelling in opposite directions.

[11] PEM is now approved in the United States and Europe for post-diagnosis imaging, with multiple commercial systems available.