Review the magnetic resonance imaging (MRI) features of low rectal tumors.
Review the role of MRI in staging and treatment planning.
The rectum extents about 15cm proximally from the anal margin.
Tumor arising in this section of the gastrointestinal tract are divided,
according to the distance of their inferior border to the anal margin,
middle and lower third tumors.
Low rectal tumors (LRT) arise within 5cm from the anal margin.
The standard of care for rectal tumors is total mesorectal excision with tumor-negative margins.
As opposed to tumors on the upper two thirds,
LRT are associated with higher rates of positive resection margins,
Findings and procedure details
Special considerations need to be taken into account when staging LRT,
namely when assessing the tumor relationship to the adjacent structures,
so to define the tumor free margin.
The staging is based on MRI and allows to assess the need for chemoradiation prior to surgery and the choosing of the most suitable surgical excision plane.
MRI staging relies primarily on T2-weighted images that better defines the tumor relationship to the rectal wall and to the adjacent structures.
The protocol starts with imaging the pelvis in...
MRI permits local staging of LRT and allows to define the tumor location relative to the anal sphincter complex,
a crucial step to decide which patients may need CRT before surgery.
staging can provide important information in surgical planning.
MRI staging of low rectal cancer,
19 (2009) 643–650.
Management and imaging of low rectal carcinoma,
13 (2004) 55–61.
The Use of MR Imaging in Treatment Planning for Patients with Rectal Carcinoma: Have You Checked the “DISTANCE”?,
268 (2013) 330–344.