Integration of quantitative DCE-MRI and ADC mapping to monitor treatment response in human breast cancer: initial results

Abstract

Purpose: The objective of this study was to assess changes in the water apparent diffusion coefficient (ADC) and in pharmacokinetic parameters obtained from the fast-exchange regime (FXR) modeling of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) during neoadjuvant chemotherapy in breast cancer. Materials and Methods Eleven patients with locally advanced breast cancer underwent MRI examination prior to and after chemotherapy but prior to surgery. A 1.5-T scanner was used to obtain T₁, ADC and DCE-MRI data. DCE-MRI data were analyzed by the FXR model returning estimates of K^trans (volume transfer constant), v_e (extravascular extracellular volume fraction) and τ_i (average intracellular water lifetime). Histogram and correlation analyses assessed parameter changes post-treatment. Results: Significant (P<.05) changes or trends towards significance (P<.10) were seen in all parameters except τ_i, although there was qualitative reduction in τ_i values post-treatment. In particular, there was reduction (P<.035) in voxels with K^trans values in the range 0.2–0.5 min⁻¹ and a decrease (P<.05) in voxels with ADC values in the range 0.99×10⁻³ to 1.35×10⁻³ mm²/s. ADC and v_e were negatively correlated (r=−.60, P<.02). Parameters sensitive to water distribution and geometry (T₁, v_e, τ_i and ADC) correlated with a multivariable linear regression model. Conclusion: The analysis presented here is sensitive to longitudinal changes in breast tumor status; K^trans and ADC are most sensitive to these changes. Relationships between parameters provide information on water distribution and geometry in the tumor environment.