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== Patient preparation ==
'''Spasmolytics (optional)'''
* Can be benefical for upper rectal tumors and when imaging is performed at 3.0T (bowel movement artifacts are most prevalent)
'''Endorectal filling (optional)'''
* '''~60 ml of gel''' (higher volumes compress perirectal tissues significantly)
* Reduce susceptibility artefacts related to luminal gas on DWI.
* Should not be used 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.
* Tumour length
* T-stage
* Sphincter invasion
** Good prognosis** Rectal wall has an intact black line (outer muscle) surrounding the tumor*'''T3: extramural growth'''(including growth into the internal anal sphincter muscle)
== N staging ==
* Important risk factor for local recurrence
'''Morphologically suspicious characteristics'''
* Round shape
* Irregular border
* Heterogeneous signal
'''Malignant node criteria'''
* Short axis diameter ≥9 mm
* Short axis diameter 5-8 mm + ≥ 2 morphologically suspicious characteristics
* Short axis diameter <5 mm + 3 morphologically suspicious characteristics
* Mucinous lymph node (of any size)
== N restaging ==
no edit summary
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This article is a practical summary of the ''Updated recommendations from the 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) to Magnetic resonance imaging for clinical management of rectal cancer''.
== MR image acquisition ==
'''MRI (first choice)'''
* Mandatory for both primary staging and restaging of rectal cancer.
* Should use Requires an external surface coil
* 1.5T or 3.0T
=== Patient preparation ===
* Use of an enema is not routinely recommended
'''Spasmolytics (optional)'''* Use of spasmolytics may be useful to reduce bowel movement artefacts (no consensus: 57 % recommended/mandatory)* Use of endorectal Can be benefical for upper rectal tumors and when imaging is performed at 3.0T (bowel movement artifacts are most prevalent) '''Endorectal filling is not (optional)'''* Not routinely advised (no consensus: 71 % not recommended)* '''~60 ml of gel''' (higher volumes compress perirectal tissues significantly)* Reduce susceptibility artefacts related to luminal gas on DWI.* Should not be used 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.
=== Sequences and sequence angulation ===
* FS, T1W (non-enhanced and contrast-enhanced) and DCE sequences are not routinely recommended
* Slice thickness ≤3 mm (axial and coronal T2W)
'''Sequence angulation'''
* 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
== Structured reporting ==
=== Local tumour status ===
==== Morphology ==== Morphology* Solid - polypoid* MorphologySolid - (semi-)annular* Mucinous Circunferential location within the rectal wall* e.g. from X to X o'clock* Should routinely be reported ==== Distance from anorectal junction ====
* Distance from the anorectal junction to the lower pole of the tumour
==== Tumour length ====
* MRI doesn't differentiate T1 from T2
*'''T1-T2: limited to intestinal wall'''
** '''T3a or T3b: ≤5 mm extramural growth'''
** '''T3c or T3d: >5 mm extramural growth'''
* '''T4'''
**T4a: Invasion of peritoneal reflection
**T4b: Invasion of surrounding organs
Observations:
* Stranding into the mesorectal fat = equivocal sign; may indicate either a T2 or T3 tumour* The mesorectal fascia (MRF) is 'involved' if the distance between MRF and tumour is ≤1 mm* Stranding into the MRF = MRF is involved* Involvement of MRF = T3* Tumour invasion above the level of the peritoneal reflection (at the anterior side) should be considered at risk for peritoneal rather than MRF invasion
* Invasion of the pelvic floor or pelvic side wall muscles = T4
* Growth into the internal anal sphincter muscle = T3
Depth of invasion
* invades only the internal sphincter muscle(T3)
* also involves the intersphincteric plane
* also involves the external sphincter
* Tumour location in relation to anterior peritoneal reflection
** below (: MRF invasion)** above: when on anterior side = at risk for peritoneal invasion (rather than MRF invasion)
Observations:* The anterior peritoneal reflection is a landmark that is usually recognised easily on MRI and separates the intra- and extra-peritoneal portions of the mesorectal compartment [20]. Above the anterior peritoneal reflection, the mesorectal compartment is no longer enveloped by the mesorectal fascia on its anterior aspect. As such, anterior mesorectal fascia involvement should only be reported when below the level of the anterior peritoneal reflection.* Mesorectal fascia involvement:** Shortest distance between tumour and MRF*** Free: >2 mm*** Threatened: 1.1-2 mm*** Involved (=T3): ≤1 mm or stranding into the MRF
=== Lymph nodes and tumour deposits ===
* Important risk factor for local recurrence
'''Morphologically suspicious characteristics'''
* Round shape
* Irregular border
* Heterogeneous signal
'''Malignant node criteria'''
* Short axis diameter ≥9 mm
* Short axis diameter 5-8 mm + ≥ 2 morphologically suspicious characteristics
* Short axis diameter <5 mm + 3 morphologically suspicious characteristics
* Mucinous lymph node (of any size)
=== Extramural vascular invasion (EMVI) ===
=== Extramural vascular invasion ===
== Treatment ==
