Dynamic MR defecography with a superconducting, open-configuration MR system

PURPOSE: To evaluate dynamic magnetic resonance (MR) defecography performed with a superconducting, open-configuration system in diagnosis of defecation disorders. MATERIALS AND METHODS: Five healthy volunteers and 15 patients with defecation disorders were studied with MR defecography performed with a superconducting, open-configuration system; the patients also underwent fluoroscopic defecography. Before MR imaging, the rectum was filled with 300 mL of mashed potatoes mixed with 1.5 mL of gadopentetate dimeglumine. T1-weighted gradient-echo images were acquired every 2 seconds in the midsagittal plane with the patient at rest, at maximal contraction of the anal sphincter, during straining, and during defecation. RESULTS: MR defecography permitted analysis of the anorectal angle, anal canal, puborectal muscle, and descent of the pelvic floor. Owing to the high signal intensity of the intraluminal contrast material, the rectal walls were well demonstrated on the MR images, permitting visualization of intussusception nad rectocele. Concomitant demonstration of structures surrounding the anorectal canal was helpful in assessment of spastic pelvic floor syndrome and descending perineum syndrome. MR defecography was superior to fluoroscopic defecography and allowed detection of all clinically relevant pathologic conditions except for one. CONCLUSION: Dynamic MR defecography is an attractive alternative for evaluation of defecation disorders.