Diffusion-weighted imaging in evaluating the response to neoadjuvant breast cancer treatment

The aim of this study was to investigate the role of diffusion imaging in the evaluation of response to neoadjuvant breast cancer treatment by correlating apparent diffusion coefficient (ADC) value changes with pathological response. From June 2007 to June 2009, all consecutive patients with histopathologically confirmed breast cancer undergoing neoadjuvant chemotherapy were enrolled. All patients underwent magnetic resonance imaging (MRI) (including diffusion sequence) before and after neoadjuvant treatment. The ADC values obtained using two different methods of region of interest (ROI) placement before and after treatment were compared with MRI response (assessed using RECIST 1.1 criteria) and pathological response (assessed using Mandard's classification). Fifty-one women (mean age 48.41 years) were included in this study. Morphological MRI (RECIST classification) well evaluated the responder status after chemotherapy (TRG class; area-under-the-curve 0.865). Mean pretreatment ADC values obtained with the two different methods of ROI placement were 1.11 and 1.02 × 10(-3) mm(2) /seconds. Mean post-treatment ADC values were 1.40 and 1.35 × 10(-3) mm(2) /seconds, respectively. A significant inverse correlation between mean ADC increase and Mandard's classifications was observed for both the methods of ADC measurements. Diagnostic performance analysis revealed that the single ROI method has a superior diagnostic accuracy compared with the multiple ROIs method (accuracy: 82% versus 74%). The coupling of the diffusion imaging with the established morphological MRI provides superior evaluation of response to neoadjuvant chemotherapy treatment in breast cancer patients compared with morphological MRI alone. There is a potential in the future to optimize patient therapy on the basis of ADC value changes. Additional works are needed to determine whether these preliminary observed changes in tumor diffusion are a universal response to tumor cell death, and to more fully delineate the ability of ADC value changes in early recognizing responder from nonresponder patients.