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.