Publisher Summary Breast scintigraphy or scintimammography is a nuclear medicine imaging technique that uses radionuclides to image malignant breast tumors and it requires the administration of a single photon-emitting radiotracer to the patient and a gamma-camera for imaging. The ideal radiopharmaceuticals for scintimammography should have high and specific tumor uptake and minimal activity within the normal breast. The most widely currently used are Tc-99m sestamibi and Tc-99m tetrofosmin, two small cationic complexes of technetium originally introduced and routinely used for myocardial perfusion imaging, and then proposed as tumor-seeking agents. The radiopharmaceutical agent is injected into the antecubital vein of the opposite arm to the known breast abnormality, or in a dorsalis pedis vein when both breasts have lesions, to avoid artifactual axillary lymph node uptake from the extravasated radiotracer via lymphatic drainage. After the injection, patients are usually imaged in the prone position, which provides improved separation of the breast tissue from the myocardium and the liver, which always show a high uptake that may mask overlying breast activity. The capacity of scintimammography to detect small tumors is critical for its clinical development and acceptance because the other breast-imaging modalities are increasingly used for the early identification of small suspicious lesions. The acquisition of tomographic images through single photon emission computed tomography (SPECT) with its better contrast resolution could play a role in increasing the sensitivity of planar scintimammography. The best option for improving planar scintimammography sensitivity in small tumor detection seems to be the use of dedicated gamma-cameras specifically built for breast imaging. The use of small field-of-view high-resolution cameras allows greater flexibility in patient positioning and breast compression, with an important increase in the target-to-background ratio.