Relative Uptake Factor of Invasive Ductal Breast Cancer in Breast-specific Gamma Imaging as a Surrogate Parameter for Sub-typing.

The retrospective evaluation of correlations between semi-quantitative breast-specific gamma imaging (BSGI) and invasive ductal breast cancer (IDC) sub-types.The biopsy specimen of 50 histologically-proven IDCs were retrospectively evaluated concerning receptor status, human epidermal growth factor receptor 2 (HER2/Neu) status, Ki-67 level and classification into IDC sub-types. These results were compared to the relative uptake factor (RUF) in BSGI. Depending on RUF, we described four categories to outline the predictive value of RUF.A total of 50 IDCs with a mean diameter of 20.36 mm were included. RUF differed reliably between luminal-A and non-luminal-A IDCs. RUF exceeding 6.5 pointed to non luminal A-carcinoma, with a specificity and positive predictive value of 100%. RUF of less than 2.6 was unlikely to be associated with a non-luminal A-carcinoma (negative predictive value: 76.5%). Comparable results were calculated for the correlation between RUF and the K-67 level.RUF may help classify the sub-type of an IDC in addition to pathology.