Table 5.

Items lacking consensus

Patient preparation

Use of spasmolytics (recommended by 57 % of the panel)

Use of endorectal filling (recommended by 29 % of the panel)

Diffusion-weighted imaging

There was no consensus on the number of b-values required (57 % consensus at least 2; 43 % consensus at least 3)

There was no consensus on whether DWI should be used for:

assessment of T-stage at primary staging (31 % not recommended; 46 % unsure*; 8 % recommended; 15 % mandatory)

assessment of N-stage at primary staging (23 % not recommended; 38 % unsure*; 31 % recommended; 8 % mandatory)

assessment of yN-stage at restaging (15 % not recommended; 31 % unsure*; 23 % recommended; 23 % mandatory)

assessment of MRF at restaging (15 % not recommended; 62 % unsure*; 15 % recommended; 8 % mandatory)

MRI performance

There was no consensus whether 2D T2-weighted MRI is reliable (≥ 80 % accurate) to:

differentiate between N0 and N+ stage at primary staging (not reliable with 69 % consensus)

assess EMVI at primary staging (reliable with 69 % consensus)

differentiate between a complete response and residual tumour at restaging (not reliable with 69 % consensus)

differentiate between yT1-2 and yT3-4 tumours at restaging after CRT (reliable with 62 % consensus)

differentiate between yN0 and yN+ stage at restaging after CRT (reliable with 62 % consensus)

differentiate between non-involved and involved MRF at restaging after CRT (reliable with 62 % consensus)

assess EMVI at restaging after CRT (reliable with 54 % consensus)

There was no consensus whether diffusion-weighted MRI is reliable (≥ 80 % accurate) to:

differentiate between a complete response and residual tumour at restaging (reliable with 54 % consensus)

differentiate between yT1-2 and yT3-4 tumours at restaging after CRT (not reliable with 69 % consensus)

differentiate between non-involved and involved MRF at restaging after CRT (not reliable with 69 % consensus)

MRI reporting

reporting of N-substages (N1a, N1b) (recommended by 31 % of the panel)

There was no consensus whether a tumour that invades the external anal sphincter should be considered a T3 (29 % consensus) or T4 (71 % consensus) tumour

*Unsure indicates that it is not routinely recommended, but may be useful for particular cases