Molecular breast imaging with gamma emitters

Following a diagnosis of breast cancer (BC), the early detection of local recurrence is important to define appropriate therapeutic strategies and increase the chances of a cure. In fact, despite major progress in surgical treatment, radiotherapy, and chemotherapy protocols, tumor recurrence is still a major problem. Moreover, the diagnosis of recurrence with conventional imaging methods can be difficult as a result of the presence of scar tissue. Molecular breast imaging (MBI) with gamma-ray emitting radiotracers may be very useful in this clinical setting, because it is not affected by the post-therapy morphologic changes. This review summarises the applications of 99mTc-sestamibi and 99mTc-tetrofosmin, the two most employed gamma emitter radiopharmaceuticals for MBI, in the diagnosis of local disease recurrence in patients with BC. The main limitation of MBI using conventional gamma-cameras is the low sensitivity for small BCs. The recent development of hybrid single photon emission computed tomography/computed tomography devices and especially of high-resolution specific breast cameras can improve the detection rate of sub-centimetric malignant lesions. Nevertheless, probably only the large availability of dedicated cameras will allow the clinical acceptance of MBI as useful complementary diagnostic technique in BC recurrence. The possible role of MBI with specific cameras in monitoring the local response of BC to neoadjuvant chemotherapy is also briefly discussed.