99mTc-MIBI scintimammography and digital mammography in the diagnosis of multicentric breast cancer

Abstract

Objective: To compare diagnostic accuracy of scintimammography (SMG) and digital mammography (DS) in the diagnosis of multicentric breast cancer.

Subjects and methods: Three hundred and sixty seven women with histologically confirmed breast cancer were included in this analysis. All patients were candidates for conservative breast surgery and had cT1-3N0-1 stage of disease. Scintimammography was performed in prone position 5-10min after intravenous injection of 740MBq of technetium-99m-methoxy-isobtyl-isonitrile (^99mTc-MIBI) with acquisition time of 10min for every lateral and anterior projection. Digital mammography was done in all women according to a standard clinical protocol. Final diagnosis was established by histopathology. Multicentric breast cancer was defined as 2 or more distinct invasive tumors located in more than one quadrant or additional lesions from the primary tumor of more than 4cm in size.

Results: According to histopathological examinations multicentric breast cancer was diagnosed in 47 of 367 (12.8%) patients. Scintimammography was more effective than mammography in detecting multicentric breast cancer: sensitivity: 83.0% vs 40.4% (P<0.001), specificity: 97.8% vs 95.3% (P=0.4), accuracy: 95.9% vs 88.3% (P<0.001), positive and negative predictive values: 84.8% vs 55.9% (P=0.004) and 97.5% vs 91.6% (P<0.001), respectively. Combination of DM and SMG was characterized by increased sensitivity (93.6%), worse specificity (93.4%), accuracy (93.4%) and worse predictive value (67.7%) as compared to only SMG.

Conclusion: Scintimammography was significantly much better by all statistical parameters than DM in the detection of multicentric breast cancer. High positive predictive value of scintimammography (84.8%) advocates it as a tool for surgery and radiotherapy planning.