EVALUATION OF DIAGNOSTIC ACCURACY OF DYNAMIC MR DEFECOGRAPHY IN COMPARISON WITH EVACUATION PROCTOGRAPHY IN PATIENTS WITH CONSTIPATION

Abstract

Background: Chronic constipation is very common, affecting 10.9% of Asian population. The etiology of constipation is also very variable and can be classified as functional or structural. The structural constipation can be examined with physical examination and colonoscopy while those without structural causes can be further evaluated with physiologic tests. The current gold standard physiologic test for constipation is evacuation proctography. However dynamic MR defecography has gained reputation as a useful tool in the evaluation of constipation as a less invasive test that spare the radiation exposure and provide better anatomy and interaction of pelvic organs. Objective: The aim of this study was to compare diagnostic accuracy of dynamic MR defecography (MR-D) with evacuation proctography (EP) in assessment of the patients who present with constipation. Materials and methods: From August 2012 to January 2013, 19 patients who required EP to assess the cause of constipation were enrolled in this study. All of these patients were asked to undergo MR-D. The images from MR-D and EP were reviewed by a radiologist expert in gastrointestinal radiology. Features evaluated included the presence and degree of anterior rectocele, rectoanal intussusception, sigmoidocele, increased fixed perineal descent and increased dynamic perineal descent. Results: No statistical difference was observed in terms of the prevalence of abnormalities detected by both EP and MR-D in this study. The sensitivity of MR-D in detecting of rectoanal intussusception, anterior rectocele and increased dynamic perineal descent was 36.4%, 64.3% and 80%, while the specificity were 87.5%, 80% and 50% respectively. The overall sensitivity and specificity of MR-D in detection of any abnormalities were 56.7% and 86.2% respectively. Sigmoidocele and increased fixed perineal descent were not found in any patients enrolled in this study. Conclusions: MR-D has lower sensitivity than EP in detection of anterior rectocele and much lower when it comes to detection of rectoanal intussusception. On the other hand, it has high sensitivity in finding increased dynamic perineal descent due to its intrinsic property. Although it is less invasive than EP in terms of radiation exposure, our method of MR-D shows no better diagnostic accuracy than that of EP. MR-D may have better role in evaluation of anterior portion of pelvic organ which cannot be examined by EP.