Unilateral breast uptake on radionuclide ventriculography

Gated equilibrium radionuclide ventriculography is frequently used to measure the left ventricular ejection fraction. We report a case of unilateral breast activity resulting in significant underestimation of the left ventricular ejection fraction, which mimicked a left ventricular aneurysm, pseudoaneurysm, or an intrathoracic vascular mass. Unilateral breast uptake, in the absence of gastric activity, was presumed because of increased blood pool in the lactating breast, a finding not previously reported in the literature. This case is also presented to emphasize the importance of localizing abnormalities based on a review of tomographic images or images taken in at least 2 orthogonal projections.