MRI Advances in Rectal Cancer

1. MRI of Early Rectal Cancer: Bisacodyl Micro-Enema Increases Submucosal Width, Reader Confidence, and Tumor Conspicuity
Viktil E, Hanekamp BA, et al. Abdom Radiol (2025)

In a prospective study of 50 patients with early rectal cancer (ERC), researchers investigated whether administering a bisacodyl micro-enema prior to MRI could improve diagnostic clarity. Each participant underwent MRI with (MRin) and without (MRex) a micro-enema. While sensitivity and specificity for T-staging did not significantly differ, the micro-enema led to increased submucosal width (mean 2.2–2.8 mm), improved reader confidence, and better tumor conspicuity. Notably, the proportion of tumors both correctly staged and rated with high reader confidence improved significantly—from 58% to 80% for Reader 1 and from 42% to 72% for Reader 2. These findings suggest that a simple, low-cost intervention like a micro-enema can meaningfully enhance MRI interpretation in early rectal cancer.

2. Staging of Rectal Cancer: MRI Protocol, Pelvic Anatomy, and Definitions
Garg D, Mehta V, et al. J Gastrointest Abdom Radiol ISGAR (2025)

This review focuses on the essentials of MRI technique and pelvic anatomy critical for accurate staging of rectal cancer. MRI remains the preferred modality for local staging due to its superior contrast resolution. Key elements emphasized include understanding the anorectal anatomy (e.g., mesorectal fascia, anterior peritoneal reflection), proper imaging planes, and the classification of tumor location (upper, mid, lower rectum). The authors also outline protocol recommendations—including sagittal, oblique axial, and oblique coronal T2-weighted imaging—and discuss high-risk features like mucinous adenocarcinoma, mesorectal fascia involvement, and tumor deposits. The paper provides a valuable guide for radiologists striving to produce structured, standardized reports that support effective multidisciplinary care.

3. How Do MRI Findings Influence Rectal Cancer Management?
Ramakrishnan AS, Pradeep J. J Gastrointest Abdom Radiol ISGAR (2025)

MRI’s role in rectal cancer has evolved from a staging tool to a critical driver of management decisions. This article emphasizes MRI’s ability to detect high-risk features such as mesorectal fascia involvement, extramural venous invasion (EMVI), lateral pelvic lymph node enlargement, and tumor deposits—each with implications for prognosis and treatment strategy. The authors advocate a risk-adapted approach using MRI findings to stratify patients for neoadjuvant therapy, total neoadjuvant treatment (TNT), or direct surgery. Additionally, restaging MRI is highlighted for evaluating treatment response, helping identify candidates for local excision or non-operative “watch-and-wait” strategies. MRI not only guides treatment but also surgical planning, especially in low rectal cancers, where accurate depiction of involvement of the sphincter complex influences surgical approach.