Introduction and hypothesisTo investigate the role of measuring the thickness of pelvic floor muscles with static MRI in the physiopathology of urinary incontinence in women with stress and mixed types of urinary incontinence diagnosed with urodynamic studies.MethodsA retrospective clinical study was designed in collaboration with the radiology department. We recruited only patients who had undergone static pelvic MRI to determine the etiology of pelvic pain and exclude gynecologic disorders. The study included 45 women diagnosed with stress or mixed-type urinary incontinence based on pelvic examination and urodynamic testing without symptomatic pelvic organ prolapse and 40 continent controls. We evaluated the images of pelvic static MRI of all patients to measure the thickness of the pelvic floor muscles with the radiologist by using an image analysis workstation retrospectively.ResultsThe right and left puborectalis parts of levator ani muscle thicknesses were significantly lower in the urinary incontinence group than in the control group (p<0.01). The right and left PR/OI ratios were significantly lower than in the control group. (p=0.001).ConclusionMorphologic changes of pelvic floor muscle thickness can be demonstrated by a static pelvic MRI, and this can be used as a prognostic test in the treatment and follow-up of patients with stress or mixed urinary incontinence.