PRACTICAL EVALUATION OF MRI IN RECTAL CANCER: WHAT THE SURGEON NEEDS TO KNOW

Introduction Magnetic resonance imaging (MRI) is the imaging method of choice for the characterization and staging of rectal cancer. Through it, preoperative anatomical study of the pelvic compartments can be performed, recognizing potential compromise of surgical planes and adjusting the operative strategy. MRI also allows the identification of high-risk criteria, aiding in the decision of whether to use neoadjuvant treatment for potential tumor downstaging and improved surgical outcomes.

Objective The objective of this work is to demonstrate, in a practical way, in seven steps, how to: - recognize a technically adequate MRI; - map the main characteristics related to TNM staging, as well as signs of locoregional involvement and adjacent structure compromise; - recognize patterns of mesorectal invasion; - recognize the mesorectal fascia and its potential tumor involvement; - identify lymph node suspicion criteria and locate the main affected chains on MRI; - screen for factors indicating poor oncological prognosis; - establish the involvement of important anatomical structures, impacting the decision of surgical and oncological strategy.

Method Evaluation of MRI exams of patients in different tumor stages, to practically demonstrate the main anatomical repairs, the manifestations of rectal cancer on MRI, and imaging findings in various clinical scenarios (TNM).

Results Systematic evaluation of MRI findings in rectal cancer, in seven steps: 1. Recognizing a technically adequate exam 2. Anatomy of the rectum on MRI 3. Mesorectal fat and mesorectal fascia 4. Evaluating the T stage 5. The challenge of lymph node evaluation 6. Extramural vascular invasion and its significance 7. Tumor resection planning with MRI

Conclusion Magnetic resonance imaging is currently an indispensable tool in the diagnosis and reassessment of patients with rectal cancer. It enables pre-treatment tumor staging, defining the best therapeutic strategy for each scenario, and contributes significantly to post-neoadjuvant tumor reassessment. It is essential, therefore, that the colorectal surgeon masters the concepts of imaging for the definition of the most appropriate surgical and oncological therapeutic strategy and for better communication with the multidisciplinary team.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
25 April 2025