Controversy	Recommendations
Do I measure from node/deposit/EMVI to mesorectal fascia (MRF) or from the primary tumor?	The distance from the primary tumor to the MRF prognosticates risk and can be used for planning treatment. Involved nodes at the MRF confer no added risk [12]. Tumor deposits and EMVI near the MRF add some risk in small studies [13] and there is no universal policy to intensify neoadjvuant therapy compared with primary tumor threatening the margin. The issue becomes more one of surgical safety. Therefore, in addition to the measurement of primary tumor to MRF, a distance from a node/EMVI or deposit that is close to the MRF should be mentioned for surgical planning to allow careful dissection on the MRF and avoid cutting through this structure.
Where is the anal verge (AV)?	A discussion with the surgeons should take place. Ascertain whether they want the measurement from the anatomic AV (bottom of the EAS) or the “surgical” AV which often is the bottom of the IAS due to anesthesia- induced relaxation of the EAS or manual separation of the EAS when placing the scope.
How should I stage low rectal adenocarcinoma?	No accepted standard exists w/r/t T-categorization. To help surgical planning, tumor should be described as tumor “involves the IAS”, “involves the ISS” or “involves the EAS”. No T-stage should be applied.
What constitutes suspicious lateral pelvic side-wall lymph nodes	Those posterior to the external iliac vessels distally (at about the acetabulum and caudally are often elongated and can be ignored [27]. All rounded, heterogenous nodes measuring >7mm pre-treatment and >5mm on post treatment MRI should be included in the report as potentially involved [26, 28].
What is included in Stage T4b?	AJCC refers to “other structures but does not define them. They can include muscles, pelvic fat outside of the mesorectum, nerves, ureters and blood vessels
Should I evaluate mucinous tumors with the routine protocol?	Because the mucin can be isointense to fat on T2, it can be useful to add an optional T2W FS or post contrast T1W FS images to fully visualize the extent of mucin invasion into surrounding fat/tissues.
Shall I use rectal filling?	This is based on personal preference but is not recommended by guidelines. For smaller tumors or if less familiar with reading rectal MRI, filling may help locate the tumor. If there is over-filling however, it can increase tumor distances from the anorectal junction.
IV contrast	Not recommended. May be useful in mucinous tumors
mrTRG	Validated response measure after XRT. May not work after chemotherapy only