Fig. 1

Example of tumor regression in a single patient between the first and last fraction of neoadjuvant treatment. Distinct decrease in gross tumor volume (GTV; red outlined) is evident (a + b: coronal and transverse T2-weighted images at baseline, e + f: coronal and transverse T2-weighted images at the end of neoadjuvant RCT). The diffusion-restricted area within the GTV (red) also declines until end of RCT, indicating the treatment-related cell depletion (c + d: transverse DWI sequence obtained with a b-value of 1000 s/mm² and corresponding ADC-map at baseline, g + h: transverse DWI sequence (b-value = 1000) and ADC-map at the end of neoadjuvant RCT; the segmented GTV (red) on the ADC-maps is given to highlight the tumor, however segmentation for the ADC calculation has been performed on high b-value images