Multiparametric Evaluation of Treatment Response to Neoadjuvant Chemotherapy in Breast Cancer Using Integrated PET/MR

Purpose: The aim of this study was to investigate whether integrated PET/MR system can predict the treatment response to neoadjuvant chemotherapy (NAC) early in the course of breast cancer treatment. Methods: Fourteen women with newly diagnosed invasive breast cancer (median age, 54.5 years) were recruited. Each participant underwent 2 PET/MR studies. Study 1 was pre-NAC; study 2 was early in NAC treatment (after the first or second cycle). PET parameters included SUVmax and total lesion glycolysis (TLG). MRI parameters included choline signal-to-noise ratio (ChoSNR), peak enhancement ratio (PER), and the minimum apparent diffusion coefficient (ADCmin). The pathologic response was categorized as a pathologic complete response or residual cellularity of less than 10% (group 1) and residual cellularity of 10% or greater (group 2). The accuracy of the NAC response prediction was obtained by receiver operating characteristic analysis. Results: Group 1 showed a greater reduction of SUVmax (percentage change,Delta% SUVmax, P = 0.013; area under the receiver operating characteristic curve [AUC], 0.898), TLG (Delta%TLG, P = 0.018; AUC = 0.878), and PER (Delta% PER, P = 0.035; AUC = 0.837) than did group 2. The ChoSNR, ADCmin, Delta%ChoSNR, and Delta% ADCmin did not differ significantly between the 2 groups. The hybrid markers, Delta%SUVmax/Delta%ADCmin (AUC = 0.976) and Delta% TLG/Delta% ADCmin (AUC = 0.905), showed greater accuracy in predicting NAC response than the individual PET/MR parameters. Conclusions: The PET/MR parameters can predict the NAC response early in the course of breast cancer treatment. The hybrid markers more accurately predicted treatment response than the individual PET/MR parameters.