Technetium-99m-tetrofosmin in diagnosis of breast cancer and axillary lymph node involvement

The aim of this study was to evaluate the accuracy of breast cancer seeking agent Tc-99m-Tetrofosmin in the detection of breast malignancy and axillary lymph node metastases.

Twenty-eight female patients (mean age 52.4) with 30 breast lesions suspected of malignancy were enrolled in the study. All the patients underwent clinical investigation, Tc-99m Tetrofosmin scintimammography (SMM), mammography (MM) and biopsy/surgery for final histopathologic diagnosis. Patients were injected intravenously with 555 MBq of Tc-99m Tetrofosmin, cubitally, in the contralateral arm to the side of suspicious lesion. Seven minute static scans or at least 2.0 million counts were obtained using single head gamma camera (Orbiter 75, Siemens). Planar images were acquired in left and right prone lateral view as well as in the supine position for an anterior view of chest and axillary region.

SMM scans of 30 breast lesions were compared to the definitive histopathology findings (HP) using decision matrix. In the group of 23 patients with positive SMM scans 19 had breast malignancy: 15 infiltrating ductal cancer, three patients with one infiltrating lobular, one papillary, one colloidal cancer and one patient with cystosarcoma phyllodes-malignant type. SMM detected primary breast malignancy with 95% sensitivity, 60% specificity and 83% accuracy. Axillary dissection was performed in 19/20 with malignant disease. The number of lymph nodes extracted and HP evaluated varied from 4 to 23 per patient. Metastatic involvement was confirmed by HP in 9 out of 20 patients. SMM detected axillary metastases with 55% sensitivity and 80% accuracy.

Our results showed that SMM might be useful as a complementary test to improve the sensitivity and specificity of conventional imaging modalities, although SMM in the staging of breast carcinoma was less reliable. Further studies to evaluate the role of SMM in metastatic node involvement are necessary.