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'''Clinical T == Primary staging'''*T1: Limited to submucosa*T2: Invading muscularis propria*T3: Invading pericolorectal tissues (mesorectal fat)*T4: Invading visceral peritoneum or other organs/structures**T4a: Penetrates to the surface of visceral peritoneum**T4b: Directly invades or is adherent to other organs/structures==
== MRI protocol ==* High resolution* Contrast medium is optional* Coronal images parallel to anal canal* Slice thickness ≤ 3 mm
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== Choice of modality MR image acquisition ==
=== Hardware ===
'''MRI (first choice)'''
* Mandatory for both primary staging and restaging of rectal cancer.
* Should use an external surface coil
* 1.5T or 3.0T
'''Endorectal ultrasound (EUS)'''
* Staging for early tumours considered for local excision
* Superior diagnostic performance for differentiating T1 from T2 tumors === Patient preparation ===* Use of an enema is not routinely recommended* (Use of spasmolytics may be useful to reduce bowel movement artefacts (no consensus: 57 % recommended/mandatory))* (Use of endorectal filling is not routinely advised (no consensus: 71 % not recommended)) === Sequences and sequence angulation ===* A routine protocol should (at least) include 2D T2-weighted sequences in 3 planes and a diffusion-weighted sequence (including at least a high b-value of ≥ 800)* Diffusion-weighted images (including Apparent Diffusien Coefficient maps) should mainly be assessed visually; quantitative ADC measurements are not routinely advised* Diffusion-weighted imaging is recommended for restaging of the yT-stage.* Fatsuppressed, T1-weighted (non-enhanced and contrast-enhanced) and dynamic contrast enhanced (DCE) sequences are not routinely recommended* Slice thickness ≤3 mm (axial and coronal T2W) '''Sequence angulation'''* Transverse sequences: perpedicular to the rectal tumour axis* Coronal sequences: parallel to the rectal tumour axis* Coronal sequence parallel to the anal canal: should be included in distal tumours to assess the relation between tumour and anal sphincter
== Patient preparation ==
* Its use is not reccomended routinely: rectal wall distension may interfere with interpretation of the distance between the tumour and the mesorectal fascia, and high T2 signal of the gel may cause T2 shine through effects on DWI.
== T staging Structured reporting ==Structured reporting is recommended and should include the items described in the report template of ESGAR.
== MRI = Local tumour status ===* Morphology* Distance from the anorectal junction to the lower pole of the tumour* Tumour length* T staging -stage* Sphincter invasion ==== T-stage ====
* MRI doesn't differentiate T1 from T2
*'''T1-T2: limited to intestinal wall'''
* '''T4'''
Observations:* Stranding into the mesorectal fat is an equivocal sign that may indicate either a T2 or T3 tumour* The mesorectal fascia (MRF) is 'involved' if the distance between MRF and tumour is ≤1 mm* When a tumour shows stranding into the MRF, the MRF should be considered involved* A tumour that involves the MRF should be considered a T3 (and not a T4) tumour* Tumour invasion above the level of the peritoneal reflection (at the anterior side) should be considered at risk for peritoneal rather than MRF invasion* A tumour that invades the pelvic floor or pelvic side wall muscles should be considered a T4 tumour* A tumour that grows into the internal anal sphincter muscle should be considered a T3 (and not a T4) tumour === Information = Sphincter invasion ====This ifformation is relevant to surgical approach ===
For low tumours with sphincter invasion, describe:
* also involves the lower 1/3 of the complex/anal canal
* involves pelvic floor (levator)
=== Mesorectal fascia (and peritoneal) involvement ===
=== Lymph nodes and tumour deposits ===
=== Extramural vascular invasion ===
== Restaging after neoadjuvant treatment ==
* Structured reporting is recommended
* When considering organ preservation (watchful waiting) after CRT, MRI findings should be correlated with clinical examination (endoscopy / digital rectal examination)
=== Local tumour status ===
* On T2-weighted MRI, a normalised, two-layered wall after CRT is suggestive of a complete response
* On T2-weighted MRI, a completely hypointense (fibrotic) residue without an isointense mass indicates a complete or near-complete response
=== Mesorectal fascia (and peritoneal) involvment ===
* If a fatpad re-appears between the tumour and MRF after CRT, the MRF should be considered uninvolved/cleared.
* Persistent stranding of tumour into the MRF should be considered an equivocal sign that may or may not indicate persistent MRF involvement
=== Lymph nodes and tumour deposits ===
* For nodal restaging the criteria described in Table 4 are recommended
=== Extramural vascular invasion ===
== N staging ==
== N restaging ==
== Treatment ==
== Downloads ==
* [https://link.springer.com/content/pdf/10.1007%2Fs00330-017-5026-2.pdf] Magnetic resonance imaging for clinical management of rectal cancer: Updated recommendations from the 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus meeting
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