Abstract P4-02-01: Normalization of compression-induced hemodynamics in patients responding to neoadjuvant chemotherapy using dynamic tomographic optical breast imaging (TOBI)
Authors: Sajjadi AY , Wanyo CM , Specht M , Schapira L , Moy B , Bardia A , Finkelstein DM , Boas DA , Carp SA , Isakoff SJ 
Published: August 2014

Background: Diffuse optical imaging using near-infrared light is emerging as a promising non-invasive method for breast neoadjuvant chemotherapy (NAC) monitoring and outcome prediction. While the majority of published studies rely on “static” assessments of tissue oxy- and deoxy- hemoglobin concentration, we have focused on extending diffuse optical tomography to capture hemodynamic changes driven by fractional mammographic compression. These hemodynamic changes are governed by the interplay of tissue biomechanics and oxygen metabolism, and thus form a novel class of optical dynamic biomarkers of breast pathology. In this study we seek to evaluate the predictive value of these biomarkers with respect to treatment outcome.

Methods: We are conducting a pilot feasibility study in female patients with unilateral locally advanced breast cancer undergoing standard of care NAC. In this analysis we focused on pre-treatment and day 30 post-treatment dynamic TOBI scans. Both breasts are compressed in turn to 4-8 lbs of force (depending on size) and optical images are acquired every 2 seconds over 2 minutes. We compute the time course of oxy (HbO), deoxy (HbR)and total (HbT) hemoglobin concentration as well as the hemoglobin oxygen saturation (SO2). Regions of interest are defined in the optical images to correspond to the radiology identified tumor location, and the healthy tissue in the same breast, respectively. We compare the time courses in the two regions at baseline, and 30 days after initiation of treatment.

Results: In this analysis we present results from 6 patients including 3 responders (defined as greater than 50% reduction in the largest tumor axis from baseline imaging and final pathology) and 3 non-responders. As the compression plates are held in place the tissue collagen matrix begins to stretch, effectively reducing the compression force. At baseline, all patients exhibited an initial decrease in HbT, HbO and SO2. In the tumor area, this was followed by little or no recovery as the compression plates were held in place. The normal tissue, in contrast, began recovering almost immediately. At day 30, the tumor area in the non-responders displayed similar time-course characteristics to day 0. Interestingly, however, at day 30 responders had a very similar time course in both the tumor and normal area, characterized by a slow recovery that begins soon after the compression plates stop moving. Table 1 summarizes the changes in total hemoglobin at t = 90 seconds.

Conclusions: At day 30 after NAC, responding tumors demonstrated “normalization” of compression induced hemodynamics in the tumor area whereas nonresponding tumors did not. This encouraging data suggests that dynamic TOBI can easily detect changes due to treatment. Complete analysis of the patient data to assess the outcome prediction ability using this novel optical imaging technology is ongoing.

Compression induced changes in total hemoglobin a t = 90 seconds during compressionΔHbTtumor- ΔHbTnormal (μM)RespondersNon-RespondersDay 0-0.65 ± 0.21-0.82 ± 0.24Day 300.10 ± 0.24-1.13 ± 0.74

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-02-01.