Strain phase of MRI for pelvic floor dysfunction can be eliminated

Pelvic floor disorders – urinary and fecal incontinence, pelvic pain, dysfunctional defecation, and pelvic organ prolapse – affect nearly one fourth of all women living in the United States, and up to half of all women aged 80 and older. Diagnostic imaging is able to confirm and characterize clinically suspected abnormalities as well as identifying unsuspected concomitant pelvic floor defects.

MR defectography, which provides structural and functional assessment of the pelvic floor, has been shown in clinical studies to provide information that leads to changes in surgical management for up to two-thirds of patients who have this examination. It consists of four separate maneuvers performed by the patient. Researchers at St. Michael’s Hospital of the University of Toronto in Ontario suggest that one of these segments – the evacuation phase – provides the same diagnostic findings as the strain phase. In an article published in the February issue of Abdominal Radiology, they explain why the strain phase is redundant and may be eliminated from a MR defectography exam for most patients.

Based on their clinical experience, co-author Errol Colak, M.D., assistant professor of radiology, and colleagues conducted a retrospective study of 80 patients who had a MR defectography exam performed between May 2011 and August 2014 to determine if the strain phase of the protocol could be eliminated without the loss of diagnostic information. The patient cohort ranged in age from 22 to 86 years, and included 12 men. The majority of clinical indications included constipation/incomplete evacuation (49%), fecal incontinence (26%), and prolapse (15%).

Two radiologists working in concensus evaluated the exams, making an assessment of the evacuation phase one week later. Images were assessed for the presence and degree of pelvic floor descent, cystocele, urethal hypermobility, uterovaginal prolapse, rectocele, and intussuception. The presence of rectal incontinence was evaluated on the strain phase, and the ability to evacuate rectal contrast was evaluated on the evacuation phase.

The radiologists determined that all abnormalities detected on the strain phase were also detected on the evacuation phase, with the exception of fecal incontinence. The evacuation phase identified substantially more abnormalities as well as more pronounced abnormalities. The authors speculated that this may have been a result of the relaxation of the pelvic floor musculature during defecation.

The authors suggest that eliminating the strain phase of the protocol for MR defectography would make the exam faster to perform, easier and more comfortable for the patient, and potentially generating more accurate results. They noted that because some patients do not clearly understand the instructions to perform the strain phase maneuver, the accuracy of the images may be questioned and reduce radiologists’ confidence in interpreting them.

Although acknowledging that the strain phase of MR defectography does allow for the assessment of urinary and fecal incontinence, they conclude that “it is redundant, and can be eliminated without the loss of diagnostic information, which will help streamline the examination, simplify patient instructions, and reduce both imaging and reporting time.”

REFERENCE

1. Bhan SN, Mnatzakanian GN, Nisenbaum R, et al. MRI for pelvic floor dysfunction: can the strain phase be eliminated? 2016 Abdom Radiol. 41;2:215-220.