^99mTc tetrafosmin has been shown to have favourable properties for the imaging of breast carcinoma. We have analysed our experience with this agent in a phase III study to determine its value preoperatively in detecting multicentric breast cancer.

^99mTc tetrafosmin mammoscintigraphy (TMS) was performed prospectively in 15 patients scheduled for excision of breast lesions known or suspected to be carcinoma on clinical examination, mammography or core biopsy. The isotope (700 MBq) was administered via a pedal vein. Anterior and lateral static views were acquired of the breasts and axillae. Scan results were compared with histology to determine the sensitivity of the test for cancer and its utility for guiding breast conservation.

Breast cancer was diagnosed in 14 of the 15 cases. Seven of these cases were mammographically malignant, the lesions being impalpable in three. TMS was falsely negative in three cases but was correctly positive in 11 (79%). One case was true-negative. There were two management decision changes (13%) correctly based on TMS. In both cases, TMS identified previously unknown multicentricity which required mastectomy rather than local excision.

TMS is limited as a screening tool but is potentially useful to assess suitability for conservative breast surgery.