Nuclear medicine advances in breast cancer imaging.

Primary breast cancer imaging can be done by various means. Mammography is the most widely used technique because of its excellent diagnostic performance, patient compliance, and cost-effectiveness ratio. Other radiological techniques (such as ultrasonography) are indicated in particular circumstances, while some (such as digital mammography and magnetic resonance imaging) seem very promising but are still under evaluation. The recent technological progress in nuclear medicine has resulted in the availability of two diagnostic procedures that have been validated by extensive international clinical experience: scintimammography with Sesta-MIBI and positron emission tomography (PET) with fluorodeoxyglucose (FDG). The general advantage of nuclear medicine imaging is that tumor-seeking radiopharmaceuticals accumulate in cancer lesions, which makes scintimammography and PET fundamentally different from the radiological techniques that image the tumor mainly on the basis of morphological alterations. Scintimammography is indicated for the study of breast lesions in patients in whom mammography is non-diagnostic or difficult to interpret; it may be useful also to assess and even predict the response to primary chemotherapy. FDG-PET is increasingly used in oncology and is particularly useful in breast cancer as it gives more accurate information than scintimammography in the evaluation of patients with ambiguous mammographies and in discriminating between viable tumor, fibrotic scar or necrosis following surgery, chemo- or radiotherapy. The FDG uptake in the tumor correlates with the histological grade and potential aggressiveness of breast cancer, which may have prognostic implications. In addition to its usefulness in the study of breast lesions, FDG-PET shows great efficacy in detecting lymph node involvement prior to surgery. Whole-body PET provides information on soft tissue and bone metastases in a single scanning session, and has an important clinical role in detecting recurrent metastatic disease. On the basis of the above-mentioned evidence, nuclear medicine techniques, integrated with radiological techniques, offer an interesting opportunity to improve the diagnostic imaging yield in breast cancer, which will eventually lead to better patient management. This paper reports on the latest developments in this field.