Value of Tc-99M-mibi scintimammography in women with impalpable breast lesions seen on mammography

Objective: To find out if Tc-99m-methoxyisobutylisonitrile scintimammograph y (MIBI) is useful in the evaluation of impalpable breast lesions in women referred for biopsy after mammography screening. Design: Observational and prospective study. Setting: Radiological screenin g campaign in Spain. Patients: 36 patients referred between September 1997 and June 1998 (37 bio psies) with impalpable breast lesions referred consecutively from a screeni ng campaign. Ages ranged from 50 to 64 years. Interventions: Mammography, u ltrasound, MIBI, and wire-guided biopsy. Main outcome measures and Results: Mean values for sensitivity, specificity , positive predictive value, and negative predictive value for scintimammog raphy were 78.9, 72.2, 75, and 76.5 respectively (p=0.002). The logistic re gression analysis showed that Tc-99m-MIBI scintimammography result predicte d (p = 0.003) the risk of breast cancer in this group of patients (odds rat io: 9.75), particularly infiltrating ductal carcinoma. Conclusions: MIBI scintimammography in patients referred for biopsy after m ammography screening does not so much rule out cancer as confirm the diagno sis. Its practical benefit would be not so much avoiding biopsy for these p atients as aiding in planning the radicality of their excision.