Value Of Dynamic Magnetic Resonance Defecography In The Diagnosis Of Chronic Constipation

OBJECTIVE: To evaluate the role of dynamic magnetic resonance defecography(DMRD) in the diagnosis of chronic constipation.METHODS: Twelve patients (nine women,three men;mean age,52.2 years) with chronic constipation were placed in a supine position and underwent MR defecography performed using FSPGR(fast-gradient echo sequences fast spoiled grass) with a closed-configuration superconducting MR system.300ml of synthetic stool(mashed corn starch) mixed with contrast agent was instilled into the rectum and a phased-array coil was placed around the pelvis. Midsagittal MR images were obtained at rest,at maximal contraction of the sphincter and at defecation. DMRD findings were compared with findings of X-ray defecography. The value of DMRD were evaluated cooperating to anorectal manometry.RESULTS: Two patients of the twelve could not finish the performance of defecation because of the inadequate propulsive forces showed by anorectal manometry during attempting to defecation. DMRD and X-ray defecography of the other 10 patients were identical on the whole, including rectal descent in 7, spastic pelvic floor syndrome in 5 anterior proctocele in 5, posterior proctocele in 2,internal prolapse in 1, hypertrophic and poorly relaxing puborectal muscle in 1.Among above, 6 patients found abnormal by DMRD was not diagnosed by X-ray defecography,including internal prolapse in 2,cystocele in 5,vaginal vault descent in 3,hypertrophic and poorlyrelaxing puborectal muscle in 1. The abnormality rate of DMRD is 100% and the coincidence rate of which and X-ray defecography was 100% except the 2 patients who without the inadequate propulsive forces. Besides DMRD can find abnormality which can not be found by X-ray defecography.CONCLUSIONS: Dynamic MR defecography does not use harmful ionizing radiation and has excellent soft tissue resolution. It can find a vast array of morphologic and functional pelvic floor disorders, and it is a valuable method in diagnosis of chronic constipation, especially the defecatory disorders caused by pelvic floor disfunction.