Dynamic MR defecography of the posterior compartment: Indications, techniques and MRI features

Pelvic floor weakness is characterized by abnormal symptomatic displacement of pelvic organs. It represents a complex clinical problem most commonly seen in middle-aged and elderly parous women. Its diagnosis remains difficult in many cases, since these disorders typically present with nonspecific symptoms, such as pelvic pain, incontinence and constipation. Fluoroscopic colpocystodefecography has been proven to surpass physical examination in the detection and characterization of functional abnormalities of the anorectum and surrounding pelvic structures. Similarly, MR defecography, performed either with an open- or closed-configuration unit, appears to be an accurate imaging technique to assess clinically relevant pelvic floor abnormalities. Moreover, MR defecography negates the need to expose the patient to harmful ionizing radiation and allows excellent depiction of the surrounding soft tissues of the pelvis. In this manuscript, we review the techniques and indications of MR defecography, and illustrate the MRI features of a vast array of morphologic and functional pelvic floor disorders, with emphasis on the posterior pelvic compartment (anorectum).