Functional metabolic tomographic optical breast imaging (TOBI) to monitor response to neoadjuvant therapy in breast cancer.

Abstract

60 Background: Recent studies using near-infrared optical measurements in breast tumors have demonstrated the promise of early monitoring of neoadjuvant chemotherapy (NAC) to predict outcome. Technologies to date have focused primarily on static measurements. Dynamic optical imaging, in conjunction with fractional mammographic compression, offers access to multiple functional and metabolic tissue biomarkers that may be used to predict treatment response. We have developed a novel tomographic optical breast imaging (TOBI) device to evaluate the early (day 7) prediction performance of this advanced technology. Methods: We are conducting a pilot feasibility study in female patients with unilateral locally advanced breast cancer undergoing standard-of-care NAC. Pre-treatment and day 7 post-treatment TOBI scans are obtained, with additional scans on day 1 of each subsequent chemotherapy cycle. The affected and contralateral normal breasts are compressed to 6-8 lbs of force and optical images are acquired once every 2 seconds for two minutes. Time-resolved oxy-(HbO), deoxy-(HbR), and total-(HbT) hemoglobin concentration and hemoglobin oxygen saturation (SO2) are calculated. The compression-induced rate of change of HbT correlates with changes in tissue blood volume indicative of biomechanical properties and the evolution of tissue SO2 estimates tissue metabolism. Results: We report initial data from two patients. One patient had a near-pathologic complete response (responder) and showed 21% and 23% decreases in HbT and HbR, respectively. The second patient had no significant response (non-responder) and had 2% and 1% decreases in HbT and HbR, respectively. Interestingly, the responder showed a dynamic decrease in HbT during compression in the tumor region at day 0 that disappeared at day 7, while the non-responder had similar rates of HbT change at both scans. Conclusions: We demonstrate for the first time the feasibility of dynamic optical breast tomography and show that optically derived parameters may be sensitive to therapyinduced changes in breast cancer. These dynamic measurements may provide novel insight into the physiologic changes in breast tumors during treatment.