Value of 99mTc-MIBI scintimammography in women with impalpable breast lesions seen on mammography.

OBJECTIVE: To find out if 99mTc-methoxyisobutylisonitrile scintimammography (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 screening campaign in Spain. PATIENTS: 36 patients referred between September 1997 and June 1998 (37 biopsies) with impalpable breast lesions referred consecutively from a screening campaign. Ages ranged from 50 to 64 years. INTERVENTIONS: Mammography, ultrasound, MIBI, and wire-guided biopsy. MAIN OUTCOME MEASURES AND RESULTS: Mean values for sensitivity, specificity, positive predictive value, and negative predictive value for scintimammography were 78.9, 72.2, 75, and 76.5 respectively (p = 0.002). The logistic regression analysis showed that 99mTc-MIBI scintimammography result predicted (p = 0.003) the risk of breast cancer in this group of patients (odds ratio: 9.75), particularly infiltrating ductal carcinoma. CONCLUSIONS: MIBI scintimammography in patients referred for biopsy after mammography screening does not so much rule out cancer as confirm the diagnosis. Its practical benefit would be not so much avoiding biopsy for these patients as aiding in planning the radicality of their excision.