Accuracy of 99mTc-sestamibi scintimammography for breast cancer diagnosis

Scintimammography using 99mTc-sestamibi is a noninvasive and painless diagnostic imaging method that is used to detect breast cancer when mammography is inconclusive. Because of the advantages of labeling with 99mTc-sestamibi and its high efficiency in detecting carcinomas, it is the most widespread agent for this purpose. Its accumulation in the tumor has multifactorial causes and does not depend on the presence of architectural distortion or local or diffuse density variation in the breast. The objective of this study was to evaluate the accuracy of scintimammography for detecting breast cancer. One hundred and fifty-seven patients presenting 158 palpable and non-palpable breast nodules were evaluated. Three patients were male and 154 were female, aged between 14 and 81 years. All patients underwent scintimammography, and the nodule was subjected to cytological or histological study, i.e., the gold standard for diagnosing cancer. One hundred and eleven malignant and 47 benign nodules were detected, with predominance of ductal carcinomas (n=94) and fibroadenoma/fibrocystic condition (n=11/n=11), respectively. The mean size was 3.11 cm (7-10 cm) among the malignant nodules and 2.07 cm among the benign nodules (0.5-10 cm). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 89, 89, 95, 78 and 89%, respectively. Analysis on the histological types showed that the technique was more effective on tumors that were more aggressive, such as ductal carcinoma. In this study, 99mTc-sestamibi scintimammography was shown to be an important tool for diagnosing breast cancer when mammography was inconclusive.