Positron Emission Tomography (PET)-Computed Tomography (CT) PET/CT Evaluation of Treatment Response in Breast Cancer

The Difference in the Change (Pre and End-treatment) of Standard Uptake Value (SUV) Between Pathological Non-responders and Responders (pCR)

Time Frame: up to 6 months (1 scan prior to chemotherapy and 2 scans prior to surgery)

The quantitative measures of standard uptake value (SULpeak and SULmax, prone and supine position) from PET were obtained. SUV = (Tracer activity in tissue)/(Injected radiotracer dose/patient weight or lean body mass) with unit microcuries/g/(millicuries/kg) (no unit after simplification). The SUV was averaged over the tumor regions. These averages were computed for each patient at each time point. All patients were were planned to be scanned three times: prior to treatment, during treatment and at the end of treatment. The change of SUV was calculated as the end of treatment value minus the pre-treatment value. Then the difference in the change between the responders and non-responders were estimated using Wilcoxon rank sum test. The pseudomedians and nonparametric confidence intervals for the difference (change of non-responders minus the change of responders) were reported for parameters SULpeak and SULmax measured for different positions. Pathological response were measured at the