There are many incidences in Nuclear Medicine where incidental findings of pathologies other than those under investigation are found. This is mainly due to the non-specific biodistribution of the radiopharmaceuticals throughout the body. Sestamibi is one such agent that can be used for multi-imaging purposes, such as cardiac, parathyroid and carcinoma imaging.
A female patient with a known history of cardiac disease presented to our department for a myocardial perfusion stress/rest study. Dipryridamole was used instead of an exercise test due to leg pain and poor patient mobility. 450MBq of 99mTc-Sestamibi was injected into the patient during stress and a further 1000MBq of 99mTc-Sestamibi during rest approximately three hours later.
Post stress/rest images illustrated not only a small inferolateral infarct, but also an abnormal focus of increased activity in the right breast in the lower outer quadrant. Knowing 99mTc-Sestamibi to have a high affinity to carcinoma cells, the abnormal focal uptake was correctly diagnosed as a breast cancer malignancy. Breast cancer was confirmed on mammography and the patient underwent breast surgery, chemotherapy and radiation therapy.
This case highlights the importance of thoroughly checking all cardiac SPECT 99mTc-Sestamibi cine images for incidental findings of other pathologies.