Evaluation of tumor cell death response in locally advanced breast cancer patients to chemotherapy treatment by scattering property estimates using ultrasound backscatter

Abstract

Breast cancer tumor response to chemotherapy in twenty nine patients was examined using quantitative ultrasound techniques. Backscatter parameters, such as the average scatterer diameter (ASD) and average acoustic concentration (AAC), were estimated from regions-of-interest in tumors prior to treatment onset and at four times during neoadjuvant chemotherapy treatment (weeks 1, 4, 8 and prior to surgery). Gaussian and Anderson form factor models were used over an analysis bandwidth of 4.5 to 9 MHz to obtain ASD and AAC estimates. The Gaussian model did not fit with the measured data as well as Anderson model. The AAC estimates yielded significant differences with therapy times in clinically treatment responded patients. Data indicated increases of 6.6 dB/cm in acoustic concentration obtained maximum at week 8 in treatment responding tumors. Non-responding tumors didn't show any significant difference in the parameters during treatment. This study demonstrates that the scattering parameters have the potential to being used in quantifying the changes in tumors during treatment noninvasively and distinguishing treatment responders and non-responders early after of treatment initiation.