 This study will evaluate the feasibility of using 18FISO-1 PETCT to image sigma-2 receptor binding in primary breast tumors and continue to evaluate the safety of the tracer in this patient population. 18FISO-1 uptake measures will be correlated with qualitative immunohistochemical staining for cell proliferation Ki67. This is an observational study in that 18FISO-1 PETCT will not be used to direct treatment decisions. 