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. Author manuscript; available in PMC: 2024 Sep 1.

Published in final edited form as: Abdom Radiol (NY). 2023 Apr 26;48(9):2836–2873. doi: 10.1007/s00261-023-03900-6

Figure 17: — 48-year-old woman with a rectal mass post TNT. (a) 5-mm straight axial T2WI slice shows an anterior scar at the site of the prior tumor (arrow). (b) Matching axial b800 DWI reveals diffusion restriction (arrow). (c) ADC map shows high signal in same area, indicating that the signal on DWI is T2 shine-through (arrow). On a subsequent MRI, mucinous degeneration was more obvious, and this case likely represented T2 shine-through from mucin.

TEACHING POINT: High signal on DWI frequently represents tumor but is non-specific and can represent edema, granulation tissues, mucin, artifact, etc. However, it is not “restriction” if the ADC map also shows high signal. Rather, it is signal from T2 effects of the DWI sequence or “T2 shine-through.”

Figure 17: — 48-year-old woman with a rectal mass post TNT. (a) 5-mm straight axial T2WI slice shows an anterior scar at the site of the prior tumor (arrow). (b) Matching axial b800 DWI reveals diffusion restriction (arrow). (c) ADC map shows high signal in same area, indicating that the signal on DWI is T2 shine-through (arrow). On a subsequent MRI, mucinous degeneration was more obvious, and this case likely represented T2 shine-through from mucin.

TEACHING POINT: High signal on DWI frequently represents tumor but is non-specific and can represent edema, granulation tissues, mucin, artifact, etc. However, it is not “restriction” if the ADC map also shows high signal. Rather, it is signal from T2 effects of the DWI sequence or “T2 shine-through.”