[Breast scintigraphy using 99mTc-sestamibi--use and limitations]

Until now scintimammography did not achieve any definite role in the assessment of breast lesions. Purpose of this study was to elaborate its use as well as the limitations of scintimammography after 500 examinations completed.

Scintigraphic findings were correlated with the histopathologic outcome of 219 patients, who underwent surgery or biopsy for histopathological confirmation. The results were determined with respect to palpability of the lesion and tumour size. Additionally, a distinct analysis was performed for the patient subpopulation with indeterminate results of previously performed physical examination, mammography, and sonography.

Overall sensitivity for scintimammography was 82.1% at a specificity of 87.5%. For palpable lesions sensitivity was 91.7% which was evidently higher as compared to 64.9% for non palpable lesions. For palpable lesions specificity was 81.1% and 88.6% for non palpable lesions. According to tumour size sensitivity ranged between 65.2% for carcinoma with a diameter < 1 cm and 93.7% for carcinoma > 1 cm. In the patients subgroup with indeterminate preliminary diagnosis (n = 143) sensitivity decreased to 71.7% at a specificity of 87.8%. Patients undergoing neoadjuvant chemotherapy showed decreasing sestamibi uptake as early as 8 days after therapy if tumour response was evident. However, small residual invasive tumours in patients with complete remission could not be visualised.

Scintimammography is neither suited for screening, nor early diagnosis of breast cancer, nor for the further evaluation of small and unclear mammographic findings. Scintimammography should not be used whenever histopathological clarification of a suspicious lesion is necessary. It is useful to further investigate patients with unclear or probably benign findings in physical examination and/or mammography and to monitor tumour response to neoadjuvant chemotherapy.