Magnetic Resonance Imaging of Rectal and Anal Cancer

Magnetic resonance imaging plays a pivotal role in the imaging and staging of rectal and anal carcinomas. Rectal adenocarcinomas and anal squamous cell carcinomas behave differently, and are staged and treated differently. This article attempts to explain these 2 entities, which share the same regions of interest, in a comprehensive manner.

Key points

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Magnetic resonance imaging plays a pivotal role in the imaging and staging of rectal and anal carcinomas.
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For rectal adenocarcinomas assessment of tumor relation to mesorectal fascia, vessel involvement, relation to pelvic floor and neighboring organs are best assessed by MRI and important to report.
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A primary squamous cell or epidermoid carcinoma of the anatomic rectum has different staging and staged differently than rectal adenocarcinoma. Avery attempt should be made to characterize tumor size, growth into neighboring organs and lymph node staging correctly.