Magnetic Resonance Imaging of the Anal Region: Clinical Applications

Abstract

Over the past years, magnetic resonance imaging (MRI) has become a cornerstone in evaluating anal canal and adjacent tissues due to its safeness, the three-dimensional and comprehensive approach, and the high soft-tissue resolution. Several diseases arising in the anal canal can be assessed through MRI performance, including congenital conditions, benign pathologies, and malignancies. Good knowledge of the normal anatomy and MRI technical protocols is, therefore, mandatory for appropriate anal pathology evaluation. Radiologists and clinicians should be familiar with the different clinical scenarios and the anatomy of the structures involved. This pictorial review presents an overview of the diseases affecting the anal canal and the surrounding structures evaluated with dedicated MRI protocol.

Perianal Inflammation or Something More?

“…The absence of a non-enhancing fluid collection and relatively less surrounding tissue edema and stranding also makes a mass or pseudo mass a likely possibility. [ 4 ] The presence of enhancing soft tissue expanding the fistula also suggests possible malignant transformation. [ 5 ]…”

“…Anal canal malignancies are classified into anal canal tumors which are predominantly epithelial in origin, and anal margin malignancies, which include malignancies arising from chronic fistulae. [ 4 ] Most commonly mucinous adenocarcinoma and much less commonly squamous cell carcinoma and basal cell carcinoma have been documented to arise in a chronic perianal fistula. [ 6 ] Exact etiology of mucinous adenocarcinomas is still unknown.…”