Figure 4: MRI tumor volume and pathologic response to combination therapy in Ewing sarcoma. (a) Region of interest analysis of T2-weighted MR datasets yielding the percent change in tumor size compared with that shown at initial value on day 0. (b) Quantitative histological results from H&E sections for viability, necrosis, and fibrosis at day 13. (c) values comparing tumor volumes between treatment groups. (d) values comparing pathologic determinants of response between treatment groups.