Diagnostic accuracy of Tc-99m-MIBI for breast carcinoma in correlation with mammography and sonography.

Abstract

To evaluate the accuracy of 99mTc-MIBI scintimammography (SMM) in differentiating malignant breast cancer from benign breast mass and in detecting axillary lymph node metastasis in comparison with mammography and ultrasonography. Comparative cross-sectional study. At the Karachi Institute of Radiotherapy and Nuclear Medicine (KIRAN), Karachi, from December 2006 to May 2007. A total of 28 patients (both with breast lumps or/and axillary masses) included were in the study. They underwent clinical examination, mammography and ultrasound imaging followed by planar SMM using a single head detector. All subjects received a 740-1110 MBq bolus injection of 99mTc-Sestamibi. 5-10 minutes and 1 hour delayed images were acquired after the injection. SMM scans were considered positive when there was focal area of increased radiotracer uptake. Qualitative (visual) as well as quantitative evaluation of scans was done and compared with ultrasound and mammography, taking histopathology as Gold standard. Sensitivity, specificity, negative and positive predictive values (NPV and PPV respectively) were determined. There were 22 patients presenting with breast lesions (20 palpable, 2 non-palpable) and 6 patients with axillary lump. Scintimammography accurately predicted malignant lesions in the breast (sensitivity 93.3%, specificity. 71.4%, PPV 87.5%, NPV 83.3%, overall accuracy 86.4%) as well as in patients with axillary metastasis (sensitivity 100%, specificity 66%, PPV 75%, NPV 100%, accuracy 83%). A combination of scintimammography with any other imaging modality provides better results than a single test to detect breast cancer. SMM has good diagnostic accuracy in the detection of breast cancer as well as in axillary metastasis in association with mammography and ultrasound.