OPTIMIZATION OF X-RAY MAMMOGRAPHY AND TC-99M METHOXYISOBUTYLISONITRILE SCINTIMAMMOGRAPHY IN THE DIAGNOSIS OF NON-PALPABLE BREAST-LESIONS

The purpose of this study was to evaluate the contribution of techneti um-99m methoxyisobutylisonitrile (MIBI) scintimammography to the early diagnosis of breast cancer in 78 patients with non-palpable breast le sions detected by mammography. In all cases biopsy was indicated and t hey were classified into three groups according to the mammographic fi ndings: high (28), intermediate (30) and low (20) mammographic probabi lity of malignancy. Histological diagnosis confirmed 37 benign and 41 malignant lesions. In the high-probability group Tc-99m-MIBI scintimam mography changed the four false-positives into true negatives at the e xpense of two false-negatives; in the intermediate group it changed ni ne of the 17 false-positives into true-negatives at the expense of one false-negative, and in the low-probability group it changed five of t he 16 false-positives into true-negatives without false-negatives. App lying scintimammography to patients included in the intermediate and l ow-probability groups together, 14 of the 33 mammographic false-positi ves were changed into true-negatives with 1 false-negative; thus, 41% of the unnecessary biopsies would have been avoided. When MIBI scintim ammography was applied to the low-probability group, the negative pred ictive value was 100% and the unnecessary biopsies would have been red uced by 31%.