Scintimammography using Tc-99m tetrofosmin

Abstract

Breast cancer, the most common malignancy in women, still poses a challenge to diagnostic procedures and therapy. Despite low specificity routine mammography is the method of choice to screen women for breast cancer. In the last years other additional diagnostic procedures such as high frequency ultrasonography (US) and especially magnetic resonance imaging (MRI) have improved breast cancer diagnosis. However, all these imaging methods are lacking in specificity which makes biopsy or surgery necessary. The purpose of our study was to evaluate prospectively the sensitivity, specificity, PPV and NPV of scintimammography with a new cationic complex Tc-99m tetrofosmin in patients with suspicious mammographic lesions. One hundred and thirty seven patients in whom mammography and/or high resolution ultrasonography (10 MHz) revealed suspicious breast lesions were studied with Tc-99m tetrofosmin scintimammography. In 84 of them biopsy and/or surgery was performed for histological evaluation. After intravenous injection of 555 MBq Tc-99m tetrofosmin planar images in anterior and lateral projections (5 min.p.i.) and SPECT imaging including 3-D-reconstruction (20 min.p.i.) were performed. Scintimammography was evaluated as negative, equivocal (+), probably (+2) or definitely (+3) positive. Planar scintimammography with Tc-99m tetrofosmin was negative in 46 patients (43 true negative-f.n; 3 false negative-f.n.) and positive in 38 patients (27 true positive-t.p.; 11 false positive-t.p.). Using SPECT imaging Tc-99m scintimammography was negative in 43 cases (41 t.n.; 2f.n.) and positive in 41 cases (28 t.p.; 13 t.p). Sensitivity of Tc-99m tetrofosmin scintimammography in this prospective study was 90%, specificity 80%, PPV 71% and NPV 93% for planar imaging and 93%, 76%, 68% and 95% for SPECT, respectively. Scintimammographic results in patients with suspicious breast lesion show, that Tc-99m tetrofosmin accumulates in breast cancer as well as in some fibroadenoma with high cellularity. However, the high NPV of 93 and 95% respectively excludes breast cancer in suspicious mammographic lesions to a very high degree and therefore reduces the need of biopsy and/or surgery in most of these patients.