Fig. 7
T2 shine-through. Post-CRT T2-weighted (a, c) and diffusion-weighted (b, d) images of two male patients who have been treated for low rectal tumors. The upper patient was a complete responder, while the patient in the bottom row still had a ypT2 tumor remnant at histopathology. A very similar fibrotic wall thickening (arrows in a and c) can be observed in both patients, reflecting the difficulties of T2-weighted MRI to assess response in case of fibrosis. In the upper patient (the complete responder), a star-shaped signal is observed in the rectal lumen (*), representing T2 shine-through of a small amount of fluid present within the rectal lumen. In the lower patient, there is a high signal with a more U-shaped configuration located at the inner margin of the fibrosis (arrowheads in d), representing the small ypT2 tumor remnant