Breast-specific gamma imaging as an adjunct modality for the diagnosis of invasive breast cancer with correlation to tumour size and grade.

OBJECTIVES The purpose of this study was to determine the sensitivity of breast-specific gamma imaging (BSGI) in the detection of invasive breast cancers and to characterise the sensitivity of BSGI based on tumour size and pathological grade. METHODS 139 females with invasive carcinoma who underwent BSGI were retrospectively reviewed. Patients were injected in the antecubital vein with 20-30 mCi (925-1110 MBq) of (99m)Tc-sestamibi. Images were obtained with a high-resolution, breast-specific gamma camera (Dilon 6800; Dilon Technologies, Newport News, VA) and were categorised based on radiotracer uptake as normal, normal with heterogeneous uptake, probably abnormal and abnormal. For a positive examination, the region of the area of increased uptake had to correlate with the laterality and location of the biopsy-proven cancer. RESULTS 149 invasive cancers in 139 patients with a mean size of 1.8 cm (0.2-8.5 cm) were included. 146 were identified with BSGI (98.0%). All cancers which measured ≥ 0.7 cm (n = 123) as well as all cancers grade 2 or higher (n = 102), regardless of tumour size, were identified with BSGI (100%). There were 6 cancers that were pathological grade 1 and measured <7 mm, of which 50% (3/6) were identified with BSGI. The overall sensitivity of BSGI for the detection of invasive breast cancer is 98.0%. The sensitivity for subcentimetre cancers is 88.5% (23/26). CONCLUSION BSGI has a high sensitivity for the detection of invasive breast cancer. Our results demonstrate that BSGI detected all invasive breast cancers pathological grade 2 and higher regardless of size and all cancers which measured ≥ 7 mm regardless of grade. BSGI can reliably detect invasive breast cancers and is a useful adjunct imaging modality for the diagnosis of breast cancer.