Fig. 13

Luminal regrowth detected by MRI and endoscopy. a High-resolution T2WI restaging after 8 weeks of completion of CRT shows a low signal intensity fibrotic full-thickness scar extending from 5 to 12 o’clock (arrow). The patient was referred to watch-and-wait. b The endoscopic view of the treated lesion after 8 weeks of completing CRT shows whitening of the mucosa with some telangiectasia and no significant residual ulceration. c Follow-up after 16 months of completion of CRT shows increased signal intensity where the scar was previously seen from 6 to 9 o’clock (arrow). The patient was referred to salvage resection with total mesorectal excision. A clear margin resection was performed. d The endoscopic view of the treated lesion after 16 months of completing CRT shows evident tumor regrowth