Case Control Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Nov 28, 2015; 7(11): 394-404
Published online Nov 28, 2015. doi: 10.4329/wjr.v7.i11.394
Magnetic resonance imaging in assessment of stress urinary incontinence in women: Parameters differentiating urethral hypermobility and intrinsic sphincter deficiency
Katarzyna Jadwiga Macura, Richard Eugene Thompson, David Alan Bluemke, Rene Genadry
Katarzyna Jadwiga Macura, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD 21287, United States
Richard Eugene Thompson, Johns Hopkins Biostatistics Center, Baltimore, MD 21205, United States
David Alan Bluemke, National Institutes of Health Clinical Center, Bethesda, MD 20892, United States
Rene Genadry, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
Author contributions: Macura KJ, Bluemke DA and Genadry R contributed to the design of the study, acquisition of data, and interpretation of data; Thompson RE performed statistical analysis of data; Macura KJ and Genadry R drafted the article; Macura KJ, Thompson RE, Bluemke DA and Genadry R made critical review of the content of the manuscript and approved the final version of the article.
Supported by The Radiological Society of North America and the Society of Computed Body Tomography and Magnetic Resonance.
Institutional review board statement: The study was approved by the Johns Hopkins University Institutional Review Board.
Informed consent statement: The study was compliant with the Health Insurance Portability and Accountability Act. Study-specific written consent was obtained from all subjects.
Conflict-of-interest statement: The authors declare no conflicts of interest regarding this manuscript.
Data sharing statement: Participants did not give informed consent for data sharing and no additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Katarzyna Jadwiga Macura, MD, PhD, Professor of Radiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, 601 N. Caroline Street, JHOC 3140C, Baltimore, MD 21287, United States. kmacura@jhmi.edu
Telephone: +1-410-9555391 Fax: +1-410-9557699
Received: June 30, 2015
Peer-review started: July 5, 2015
First decision: July 31, 2015
Revised: August 22, 2015
Accepted: September 29, 2015
Article in press: September 30, 2015
Published online: November 28, 2015
Abstract

AIM: To define the magnetic resonance imaging (MRI) parameters differentiating urethral hypermobility (UH) and intrinsic sphincter deficiency (ISD) in women with stress urinary incontinence (SUI).

METHODS: The static and dynamic MR images of 21 patients with SUI were correlated to urodynamic (UD) findings and compared to those of 10 continent controls. For the assessment of the urethra and integrity of the urethral support structures, we applied the high-resolution endocavitary MRI, such as intraurethral MRI, endovaginal or endorectal MRI. For the functional imaging of the urethral support, we performed dynamic MRI with the pelvic phased array coil. We assessed the following MRI parameters in both the patient and the volunteer groups: (1) urethral angle; (2) bladder neck descent; (3) status of the periurethral ligaments, (4) vaginal shape; (5) urethral sphincter integrity, length and muscle thickness at mid urethra; (6) bladder neck funneling; (7) status of the puborectalis muscle; (8) pubo-vaginal distance. UDs parameters were assessed in the patient study group as follows: (1) urethral mobility angle on Q-tip test; (2) Valsalva leak point pressure (VLPP) measured at 250 cc bladder volume; and (3) maximum urethral closure pressure (MUCP). The UH type of SUI was defined with the Q-tip test angle over 30 degrees, and VLPP pressure over 60 cm H2O. The ISD incontinence was defined with MUCP pressure below 20 cm H2O, and VLPP pressure less or equal to 60 cm H2O. We considered the associations between the MRI and clinical data and UDs using a variety of statistical tools to include linear regression, multivariate logistic regression and receiver operating characteristic (ROC) analysis. All statistical analyses were performed using STATA version 9.0 (StataCorp LP, College Station, TX).

RESULTS: In the incontinent group, 52% have history of vaginal delivery trauma as compared to none in control group (P < 0.001). There was no difference between the continent volunteers and incontinent patients in body habitus as assessed by the body mass index. Pubovaginal distance and periurethral ligament disruption are significantly associated with incontinence; periurethral ligament symmetricity reduces the odds of incontinence by 87%. Bladder neck funneling and length of the suprapubic urethral sphincter are significantly associated with the type of incontinence on UDs; funneling reduced the odds of pure UH by almost 95%; increasing suprapubic urethral sphincter length at rest is highly associated with UH. Both MRI variables result in a predictive model for UDs diagnosis (area under the ROC = 0.944).

CONCLUSION: MRI may play an important role in assessing the contribution of hypermobility and sphincteric dysfunction to the SUI in women when considering treatment options.

Keywords: Magnetic resonance imaging, Stress urinary incontinence, Women, Urethra hypermobility, Intrincic sphincter deficiency, Urodynamics, Dynamic magnetic resonance imaging

Core tip: Magnetic resonance imaging (MRI) allows visualization of the female urethra and periurethral tissues relevant to stress urinary incontinence (SUI). The role of MRI in the specific diagnosis of SUI caused by urethral hypermobility (UH) and/or intrinsic sphincter deficiency (ISD) has not been documented. The purpose of this pilot study was to define the MRI parameters differentiating UH and ISD types of incontinence, and assess their ability to predict the type of SUI when urodynamic (UD) results are used as a reference standard. Bladder neck funneling and length of the suprapubic urethral sphincter on MRI were significantly associated with the type of incontinence on UDs.