Restricted Diffusion Volume (RDV): a novel quantitative metric to improve prediction of breast cancer response to neoadjuvant chemotherapy

Motivation: Diffusion-weighted imaging can be used to monitor treatment response in breast cancer. The conventional approach of measuring ADC requires manual processing and moderate predictive performance early in treatment. Goal(s): To develop an objective measurement of diffusion response and evaluate its predictive performance. Approach: Retrospective analyses were performed using data from the ACRIN 6698 trial. The restricted diffusion volume (RDV) was calculated by summing pixels meeting multiple objective criteria, including ADC in the range [0.6, 1.4] x10-3 mm2/s. The predictive performance of RDV was compared to conventional ADC and contrast-enhanced imaging. Results: RDV outperformed ADC early in treatment and matched its performance post-treatment. Impact: RDV is a novel, semi-automated diffusion metric that provides improved performance over conventional ROI-mean ADC. This can be used to optimize treatment and could lead to contrast-free therapy monitoring.