OBJECTIVETo test the clinical value of using Tc-99m MIBI scintimammography (Tc-99m MIBI SMM) to differentiate nodular lesions in breasts and detect axillary lymph node metastases of breast cancer.

METHODSThe subjects consisted of sixty female patients exhibiting unilateral palpable breast mass. The early and delay static acquisitions were undertaken in all subjects at 10 and 90 min after injection with Tc-99m MIBI. The acquisition included three positions: anterior supine, left lateral prone and right lateral prone. A special device for SMM which was developed by our laboratory was used. The ratio of [(T-B)/(NT-B)] was calculated as radioactivity of mass to that of opposite corresponding tissue, and [(T-B)/(NT-B)] > or = 1.21 was used as the cut-off for semi-quantitative discrimination of malignancy from benignity in semi-quantitative analysis. The final diagnosis was obtained from histology examination in all subjects.

RESULTSUsing Tc-99m MIBI SMM to differentiate between nodular lesions in breasts, the diagnostic sensitivity and specificity were 92.9% and 90.6% respectively, the positive predictive value 89.7%, the negative predictive value 93.5%, and the accuracy 91.7%. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy obtained with Tc-99m MIBI SMM for detecting axillary lymph node metastases were 83.3%, 86.1%, 80%, 88.6% and 85% respectively.

CONCLUSIONSIt is suggested that Tc-99m MIBI SMM may be not only valuable in differentiating malignant lesions from benign nodular masses of breast, but also helpful in detecting axillary lymph node metastases of breast cancer.