Fig. 2

MR images of a 52-year-old woman with good response to chemoradiotherapy. Baseline sagittal (a), axial (b), and coronal (c) T2-weighted images showing neoplastic tissue in the upper rectum with diffuse infiltration of the rectal wall and mesorectal fat (T3). The freehand ROI is drawn on the original image of the T2 maps (d), and then 72 ms of T2 value is calculated accordingly, which appears green on the color-coded image (e). This patient is confirmed to have tubular adenocarcinoma by biopsy (f, hematoxylin–eosin stain, original magnification ×100). At the end of radiotherapy, the tumor volume is reduced (g–i), the T2 value of the tumor is decreased to 60 ms (j, k), and the relative T2 is decreased to 16.7%. After CRT, the tumor volume is further reduced (l–n), and the T2 value is decreased to 52 ms (o, p) (the patchy red areas on the color-coded image represent fibrosis). The postoperative pathology is classified as TRG 1, with no residual tumor cells found in fibrosis (q, hematoxylin–eosin stain, original magnification ×100)