Tc-99m MDP scintimammography in palpable and nonpalpable breast lesions: Comparison with mammographic probability of malignancy

We evaluated the contribution of Tc-99m methylene diphosphonate (MDP) scint imammography (MDP-SMM) to the diagnosis of breast cancel in 96 patients wit h 109 (52 palpable, 57 nonpalpable) breast lesions and compared them with m ammography. Mammographic classification of the lesions were done as probabl y malignant (29), indeterminate (29) and probably benign (51). There were 2 3 malignant and 86 benign lesions. MDP-SMM successfully detected 16 of 23 ( 70%) breast cancers. Twelve of the 13 palpable and 4 of the 10 nonpalpable cancers showed Tc-99m MDP accumulation. Eight of the 86 (9%) benign breast lesions showed Tc-99m MDP accumulation (false positives). In the mammograph ically indeterminate group, MDP-SMM changed 22 of the 24 false positives in to true negatives and showed 2 false negatives. In the 35 lesions detected in dense breasts, 10 of the 13 false positives were changed into true negat ives and showed 1 false negative. As a conclusion, combined use of MDP-SMM with mammography seems to be usefull in cases with mammographically indeter minate breast lesions and dense breasts and may help to preclude unnecessar y breast biopsies.