SCINTIMAMMOGRAPHY USING TC-99M TETROFOSMIN

Breast cancer, the most common malignancy in women, still poses a chal lenge to diagnostic procedures and therapy. Despite low specificity ro utine mammography is the method of choice to screen women for breast c ancer. In the last years other additional diagnostic procedures such a s high frequency ultrasonography (US) and especially magnetic resonanc e imaging (MRI) have improved breast cancer diagnosis. However, all th ese imaging methods are lacking in specificity which makes biopsy or s urgery necessary. The purpose of our study was to evaluate prospective ly 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 m ammography and/or high resolution ultrasonography (10MHz) revealed sus picious breast lesions were studied with Tc-99m tetrofosmin scintimamm ography. In 84 of them biopsy and/or surgery was performed for histolo gical evaluation. After intravenous injection of 555 MBq Tc-99m tetrof osmin planar images in anterior and lateral projections (5 min.p.i.) a nd SPECT imaging including 3-D-reconstruction (20 min.p.i.) were perfo rmed. Scintimammography was evaluated as negative, equivocal (+), prob ably (++) or definitely (+++) positive. Planar scintimammography with Tc-99m tetrofosmin was negative in 46 patients (43 true negative-t.n.; 3 false negative-f.n.) and positive in 38 patients (27 true positive- t.p.; 11 false positive-f.p.). Using SPECT imaging Tc-99m scintimammog raphy was negative in 43 cases (41 t.n.; 2f.n.) and positive in 41 cas es (28 t.p.; 13 f.p). Sensitivity of Tc-99m tetrofosmin scintimammogra phy in this prospective study was 90%, specificity 80%, PPV 71% and NP V 93% for planar imaging and 93%, 76%, 68% and 95% for SPECT, respecti vely. Scintimammographic results in patients with suspicious breast le sion show, that Tc-99m tetrofosmin accumulates in breast cancer as wel l as in some fibroadenoma with high cellularity. However, the high NPV of 93 and 95% respectively excludes breast cancer in suspicious mammo graphic lesions to a very high degree and therefore reduces the need o f biopsy and/or surgery in most of these patients.