MRI for pelvic floor dysfunction: can the strain phase be eliminated?

Purpose: The purpose of the study was to determine if the strain phase of an MR defecography (MRD) protocol is redundant and can be eliminated without a loss of diagnostic information. Materials and methods: Institutional review board approval was obtained and the requirement for informed consent was waived. A retrospective single-center review of 80 MRD examinations (68 female, 12 male, mean age 55 years old) was conducted. Two radiologists blinded to patient information evaluated in consensus the strain and evacuation phases separately and in a random order. Each phase was assessed for the presence and degree of posterior compartment descent, cystocele, urethral hypermobility, uterovaginal prolapse, rectocele, rectal intussusception, and enterocele. The degree of pelvic floor descent was compared using a paired t test and McNemar's test was used to compare the proportion of abnormal findings. Results: The evacuation phase identified all abnormalities identified on the strain phase and also identified both additional and more pronounced abnormalities, including an additional 34 cystoceles, 20 cases of urethral hypermobility, 13 uterovaginal prolapses, 36 rectoceles, 5 rectal intussusceptions, and 6 enteroceles (all p < 0.02). The mean posterior compartment descent was 24.1 mm greater on the evacuation phase than the strain phase (p < 0.0001). Conclusion: The strain phase is redundant and we propose that it can be eliminated from a routine MRD protocol. This will help streamline the examination, simplify patient instructions, and reduce both imaging and reporting time.