High resolution in vivo characterization of apparent diffusion coefficient at the tumor-stromal boundary of breast carcinomas: A pilot study to assess treatment response using proximity-dependent diffusion-weighted imaging

Purpose To evaluate diffusion changes in the breast tumor-stromal boundary and adjacent tissue in response to neoadjuvant chemotherapy using high resolution diffusion-weighted imaging (HR-DWI). Materials and Methods Seven patients with invasive breast cancer were imaged with HR-DWI before and early during treatment. The mean apparent diffusion coefficient (ADC) was plotted in 1-mm increments around the tumor boundary. Early change in ADC was measured for tumor, tumor boundary, and stromal regions, and the relationship to treatment response was evaluated using Spearman's correlation. Results Statistically significant correlations between treatment response and early changes in ADC were found for: (i) whole tumor (rho = 0.93, 95% confidence interval [CI] = (0.58, 0.99), P = 0.003); (ii) tumor rim (rho = 0.75, 95% CI = (-0.007, 0.96), P = 0.05); and (iii) boundary transition region (rho = 0.86, 95% CI = (0.29, 0.98), P = 0.01). Early change in ADC of distal stroma had a marginally statistically significant positive correlation to treatment response (rho = 0.71, 95% CI = (-0.084, 0.95), P = 0.07). Conclusion Proximity-dependent evaluation of HR-DWI data in the breast tumor-stromal boundary and adjacent tissue may provide information about response to therapy. J. Magn. Reson. Imaging 2014;39:1308-1313. (c) 2013 Wiley Periodicals, Inc.