Dogan, Basak

Elevated intratumoral interstitial fluid pressure (IFP) can negatively impact the efficacy of neoadjuvant chemotherapy (NAC) of breast cancer. This study aims to predict breast cancer pathological complete response (pCR) to NAC based on IFP measures by 3-D subharmonic-aided pressure estimation (SHAPE). SHAPE uses the inverse linear relationship between hydrostatic pressure and subharmonic signal magnitude from intravascular ultrasound contrast agents. Thirty-eight breast cancer patients undergoing NAC from three clinical sites were enrolled for this study. SHAPE data were collected for each subject at 0%, 10%, and 30% of NAC completion using a Logiq E9 system (GE HeathCare) equipped with an RSP6-16D probe. The contrast agent used was Definity (Lantheus Medical Imaging). The subharmonic signal gradients between tumor and adjacent normal tissue were calculated and compared with patient pathological response outcome using t-test and receiver operating characteristic (ROC) curve analysis. Pressure gradients between pCR (15 patients) and non-pCR (23 patients) groups were significantly different at 0 (p = 0.02), 10 (p = 0.03), and 30% (p = 0.0003) completion of NAC. Area under the curve values of 0.69, 0.77, and 0.86 were achieved at 0%, 10%, and 30% of NAC completion, respectively. Overall, SHAPE pressure gradients may aid prediction of NAC pathological response in breast cancer patients.