Mammography and Tc-99m-MIBI scintimammography in suspected breast cancer

The aim of this work has been to evaluate whether a diagnostic protocol bas ed on the joint use of mammography and Tc-99m-methoxyisobutyl isonitrile (M IBI) scintimammography is capable of reducing the number of biopsies requir ed in patients with suspected breast cancer. Methods: We performed prone sc intimammography in 90 patients with suspected breast cancer, involving 97 l esions. In all patients, the diagnosis was established by way of biopsy. On mammography, we evaluated the degree of suspicion of malignancy and the si ze of the lesion (smaller or larger than 1 cm in diameter). Results: The re sults of only 41 of the biopsies indicated malignancy. On mammography, 20 l esions (of which 1 was breast cancer) were considered to be of low suspicio n of malignancy, 31 (of which 4 were breast cancer) as indeterminate and 46 (of which 36 were breast cancer) as high. Fourteen lesions (2 low probabil ity, 2 indeterminate and 10 high) were smaller than 1 cm, whereas 83 (18 lo w probability, 29 indeterminate and 36 high) were larger. The sensitivity, specificity, positive predictive value and negative predictive value of sci ntimammography were 85%, 79%, 74% and 88%, respectively. Scintimammography was positive in all cases of breast cancer that initially had a low or inde terminate suspicion of malignancy according to mammography, as well as in 3 0 cases of breast cancer that initially were highly suspicious. Six false-n egative scintimammography studies were obtained in lesions with a high susp icion of malignancy. Conclusion: We propose a diagnostic protocol with a bi opsy performed on lesions that have a high suspicion of malignancy as well as those with low or indeterminate suspicion that are smaller than 1 cm or with positive scintimammography results. This would have reduced the total number of biopsies performed by 34%. More importantly, there would have bee n a 65% reduction in number of biopsies performed in the low and indetermin ate mammographic suspicion groups. All 41 cases of breast cancer would have been detected.