Histogram analysis of apparent diffusion coefficients after neoadjuvant chemotherapy in breast cancer

Purpose: To evaluate the changes in the apparent diffusion coefficient (ADC) histogram during neoadjuvant chemotherapy (NAC) for breast cancer, and to compare the observed changes in pathologically verified responders and non-responders. Materials and methods: Sixty-two patients received NAC followed by surgery. Responders were defined by a tumor cell reduction of at least 30 % using the Miller–Payne grading system. All the patients underwent 3T magnetic resonance with diffusion-weighted imaging (b values of 0 and 750 s/mm ² ) before the NAC and after the completion of two cycles of NAC. Results: Mean, minimum, 10th, 25th, 50th, and 75th percentile of ADCs significantly increased after NAC and maximum ADC significantly decreased. Skewness became less positive and kurtosis decreased. A tendential, although not statistically significant, higher increase in mean, minimum, 10th, 25th, 50th, 75th, and 90th percentiles of ADCs was observed in responders in comparison with non-responders. Conclusion: ADC histogram analysis quantitatively demonstrates the alterations during the treatment course.