Table 2.

MRI and ultrasound criteria for T-staging^a

Stage	MRI findings	Ultrasound findings
T1	Abnormal signal in the submucosal layer not extending into muscle coat	Breach/irregularity of the submucosa (middle hyperechoic layer) without alteration of the muscularis propria
T2	Abnormal intermediate signal within muscularis propria	Distinct complete breach of the submucosa with invasion into/expansion of the muscularis propria (outer hypoechoic area)
T3	Broad-based bulge or nodular projection or intermediate signal projecting beyond outer muscle coat	Overt infiltration into the perirectal fat
T4	Extension of abnormal signal into adjacent organ or peritoneal reflection	Loss of normal hyperechoic interface between tumour and adjacent organ(s)

^aMR criteria adapted from Brown et al.^[54]