Magnetic Resonance Imaging of Anorectal Neoplasms

Among imaging techniques, magnetic resonance imaging (MRI) has evolved as the most robust technique for the detection, characterization, and staging of anorectal cancers. With its superior contrast resolution, multiplanar imaging capability, and nil radiation risk, it has become the standard preoperative imaging tool in rectal tumors. In this article we aim to outline the various types of anorectal cancers, highlight the complex anatomy of this region, and discuss the immensely useful role of MRI in the management of anorectal cancers. Existing limitations and future applications in this area will also be discussed. Because rectal adenocarcinomas constitute the majority of tumors in this region, we will be discussing the input of MRI in the management of this condition in greater detail. This will be followed by an overview of MRI in anal carcinoma and other less common anorectal neoplasms.

Abbreviations used in this paper: CRM, circumferential resection margin, CT, computed tomography, EUS, endoluminal ultrasound, GIST, gastrointestinal stromal tumors, MRI, magnetic resonance imaging, PPA, pelvic phased array, SPGR, spoiled gradient recalled acquisition, TME, total mesorectal excision, USPIO, ultrasmall superparamagnetic iron oxide