MRI DEFECOGRAM – USEFULNESS OF DEFECATION PHASE IN DETECTION OF RECTAL PATHOLOGIES.

OBJECTIVE. The purpose of this study was to assess the usefulness of the defecation phase during dynamic MR defecography in detecting rectal pathologies. MATERIALS AND METHODS. The images from 50 MR defecographic examinations (50 patients; age range, 13-73 years; mean, 49.88) were retrospectively reviewed in consensus by two observers. Images from each of four phases (rest, maximal sphincter contraction and squeezing, maximal straining, and defecation) were evaluated and scored independently with a previously published grading and scoring system. Features evaluated included the presence and degree of rectal descent and the presence and size of rectocele and intussusception. Statistical analysis was performed with a variety of tests. RESULTS. Compared with images obtained in the other phases, defecation phase images helped in identification of additional cases of rectoceles in 23 examinations (62%), rectal descent in 10 examinations (40%) and intussusception in 2 examinations (67%). The number of additional cases of abnormalities identified on defecation phase images was significantly greater than the number identified on images obtained in the other phases. The average total scores for the rest, squeeze, strain, and defecation phases were 0.06 (SD,0.24), 0.16 (SD,0.37), 0.82 (SD, 0.66), and 1.86 (SD, 0.78). The average total defecation phase score was significantly greater than the average total score in any of the other phases (p < 0.001). CONCLUSION. During dynamic MR defecography, defecation phase imaging yields important additional information on the presence and degree of pelvic floor abnormalities and is therefore an essential component of MR defecographic examinations.