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 [99m]Tc-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