Scintimammography in the diagnosis of breast cancer

Mammography has a positive predictive value in the detection of breast cancer of 15% to 25%. Ten percent of patients with breast cancer present with normal mammograms; however, the false negative rate is increased in younger patients. The purpose of this study was to evaluate the effectiveness of Tc-99m Sestamibi imaging in the diagnosis of breast disease.

Images were collected on 147 women. Patients were evaluated with a combination of physical examination, sonography, and mammography. Each patient received 20 millicuries of Tc-99m Sestamibi intravenously. Anterior and lateral images were obtained, the latter with the patient prone and the breast in the dependent position.

One hundred seven patients showed no enhancement (negative scan). Seven of these patients were found at biopsy to have carcinoma. Five had ductal carcinoma in-situ (DCIS) with no associated mass, 1 had an incidental 3 mm focus of invasive ductal carcinoma (IDC), and 1 had a 5-cm cystic lesion with IDC. Forty-one patients showed focal enhancement on their scans (positive scan). Thirty-six were found to have either invasive or in-situ cancer. Four of the 5 patients with benign findings had sclerosing adenosis. The positive and negative predictive values for scintimammography in this group of patients were 88% and 93%, respectively. The sensitivity and specificity were 84% and 95%, respectively.

We conclude that scintimammography is a highly specific test that deserves study as a modality to further refine the indications for breast surgery.