Scintimammography enhances negative predictive value of non-invasive pre-operative assessment of breast lesions

Aims: The aim of this study was to develop a criterion with a high negative predictive value for the evaluation of breast lesions. We aimed to determine the value of combining three non-invasive tests, mammography (MM), ultrasonography (USS) and 99mTc-methoxyisobutylisonitrite (99mTc-MIBI) scintimammography (scinti-MM). Methods: We included 94 consecutive patients with suspected lesions detected by mammography or on physical examination. MM, USS and scinti-MM were performed no more than 4 weeks prior to excisional biopsy in all patients. We then compared the biopsy results with a score calculated for each patient, derived from the results of the three tests, which we termed «mamma malignancy index» (MMI). Results: Each of the three exams yielded a score ranging from 0 to 2, with 0 representing an almost certainly benign lesion, 1 an indeterminate finding and 2 a likely malignant lesion, and hence giving a total score ranging from 0 to 6. The biopsy results showed that the lesions in 64 patients were benign. Forty-nine (77%) of these patients had received an MMI score of 0 or 1. The negative predictive value for malignancy in patients with a score less than 2 was 100%.Conclusions: Since the smallest detected lesion was 9 mm in diameter, we conclude that MMI may be a highly useful diagnostic tool in the delineation of breast lesions ≥1 cm which should not be routinely referred for biopsy but may be followed non-invasively. Although fine needle aspiration has limitations, we would recommend it as a less invasive method to evaluate suspected lesions smaller than 1 cm.