The value of early and double phase Tc-99(m)-sestamibi scintimammography in the diagnosis of breast cancer

The aim of this study was to assess the additional value of early and doubl e phase scintimammography (SMM) with Tc-99(m)-sestamibi in the detection of breast cancer following initial evaluation by palpation and mammography. A ltogether, 322 women with breast lesions evaluated prospectively by palpati on, fine-needle aspiration and mammography were assigned a malignancy risk according to the results. Scintimammography was performed in all patients i n the prone breast dependent position. Immediate and delayed views were obt ained. Acquisition of immediate tracer uptake was termed 'early phase' SMM, whereas a combination of both immediate and delayed phase images was terme d 'double phase' SMM. All patients underwent breast biopsy. Both early phas e and double phase SMM detected eight of nine tumours in the low-risk group (88.8% sensitivity). In the uncertain cases (moderate-risk group), early p hase SMM detected all malignant tumours, but double phase SMM missed one (9 2.3% sensitivity). Ln the high-risk group, early phase SMM missed two breas t cancers (94.6% sensitivity) and double phase SMM missed four (89.2% sensi tivity). Overall, early phase SMM had a sensitivity of 94.9% and a specific ity of 80.2% in detecting breast cancer, whereas double phase SMM had a sen sitivity of 89.8% and a specificity of 94.3%. Both methods had 100% sensiti vity for rumours larger than 1 cm. In conclusion, SMM detected additional b reast cancers following an initial evaluation by palpation, fine-needle asp iration and mammography. Our results suggest that double phase SMM is more specific than early phase SMM, although early phase SMM is more sensitive. Whether the interpretation of SMM results should rely on both early and del ayed images, or early images alone, should be based on the relative risk of malignancy of the breast lesion as estimated by the initial evaluation. (( C) 2000 Lippincott Williams & Wilkins).