Clinical Relevance and Practical Approach for Challenging Rectal Cancer MRI Findings

Abstract

MRI is the standard of care for clinical staging of rectal cancer, but has limitations. The purpose of this review is to describe and simplify the clinical relevance of common challenging findings on rectal cancer MRI, and to outline a practical approach to these findings for radiologists. Recent literature regarding T2 versus T3 stages, extramural depth of invasion, circumferential resection margin/mesorectal fascia involvement, anal sphincter involvement, anterior peritoneal reflection involvement, extramural vascular invasion, and lymph node involvement are reviewed. These findings are structured by the surgical implications, oncological implications, and prognostic implications, with a practical approach summary for each finding. The clinical implications of common challenging rectal cancer MRI findings are summarized with up-to-date supporting evidence and useful suggestions for practicing radiologists.