82-Rubidium (82Rb) is a photon-emitting radionuclide utilized in positron emission tomography (PET) myocardial perfusion imaging (MPI) for the detection of myocardial ischemia.

The isotope, with its short half-life of 1.3 minute, is especially handy as it is produced in a small generator and not in a cyclotron. The short half-life requires rapid image acquisition, consequently resulting in a short study time and a relatively small radiation dose for the patient and the staff.1

Extracardiac findings in patients undergoing 82Rb PET myocardial perfusion scans (82Rb-MPI) are well documented, with incidences estimated as high as 16.5% with malignant etiologies in 2% of the total patients referred.2

Previously unknown cancers diagnosed by 82Rb-MPI are to our best knowledge exceedingly rare, consisting of 2 reports of metastatic breast cancer.2,3

In this case, we present a female patient undergoing 82Rb PET MPI, which incidentally revealed unknown primary breast cancer.