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 Ktrans (volume transfer constant), ve (extravascular extracellular volume fraction) and τi (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 τi, although there was qualitative reduction in τi values post-treatment. In particular, there was reduction (P<.035) in voxels with Ktrans 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 ve were negatively correlated (r=-.60, P<.02). Parameters sensitive to water distribution and geometry (T1, ve, τi and ADC) correlated with a multivariable linear regression model. Conclusion: The analysis presented here is sensitive to longitudinal changes in breast tumor status; Ktrans and ADC are most sensitive to these changes. Relationships between parameters provide information on water distribution and geometry in the tumor environment.
- Fast-exchange regime
- Neoadjuvant chemotherapy