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This article is a 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 ==
* 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 ===
'''Sequences'''* A routine protocol should (at least) include :** 2D T2-weighted T2W sequences in 3 planes and a diffusion-weighted ** DWI sequence (including at least a high b-value of ≥ 800≥800)* Diffusion-weighted DWI images (including Apparent Diffusien Coefficient ADC maps) should mainly be assessed visually; quantitative ** Quantitative ADC measurements are not routinely advised* Diffusion-weighted imaging DWI is recommended for restaging of the yT-stage.* FatsuppressedFS, T1-weighted T1W (non-enhanced and contrast-enhanced) and dynamic contrast enhanced (DCE) sequences are not routinely recommended
* Slice thickness ≤3 mm (axial and coronal T2W)
* T-stage
* Sphincter invasion
==== Tumour length ====
Although the panel agreed unanimously that ‘some measure of tumour size’
should be reported, there was no clear consensus on a specific metric, i.e. whether this should be one-dimensional, threedimensional or a volume measurement, and if and how after CRT an estimation of the tumour volume reduction should be provided. There is no solid evidence that favours one over
another, although some authors have suggested that, specifically for assessment of chemoradiotherapeutic response, whole volume measurements may be preferable [23]. The panel acknowledges that several options exist but from a practical point of view decided to include tumour length as the main metric in the structured report template in Fig. 1, as this was deemed to be most commonly used and more practically applicable than other metrics, with good reported measurement reproducibility [20, 23, 24].
==== T-stage ====
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 Stranding into the MRF, the = MRF should be considered is involved* A tumour that involves the Involvement of 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 Invasion of the pelvic floor or pelvic side wall muscles should be considered a = T4 tumour* A tumour that grows Growth into the internal anal sphincter muscle should be considered a = T3 (and not a T4) tumour
==== Sphincter invasion ====
This ifformation information is relevant to surgical approach
For low tumours with sphincter invasion, describe:
=== Mesorectal fascia (and peritoneal) involvement ===
* Shortest distance betwenn tumour and MRF
** Free (>2 mm)
** Threatened/involved (≤2 mm)
*Location of the shortest distance between tumour and MRF
* Tumour location in relation to anterior peritoneal reflection
** below (MRF invasion)
** above
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.
=== Lymph nodes and tumour deposits ===
=== Extramural vascular invasion (EMVI) ===* Assessment of extramural vascular (or venous) invasion (EMVI) should be reported routinely, both for primary staging as well as for restaging after CRT.* EMVI is an important prognostic staging factor
== Restaging after neoadjuvant treatment ==
* 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 involvement ===
* 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 ===
=== Extramural vascular invasion ===
== N staging ==
