Report from SCBT/MR: Dynamic MR plays role in female urethra evaluation

Imaging women with MR while they perform stress maneuvers can identify and characterize unsuspected pelvic organ prolapse, compared with imaging them while at rest, according to a study presented in Phoenix at the annual meeting of the Society of Computed Body Tomography and Magnetic Resonance.

A: Midline sagittal TrueFISP image in patient referred to rule out urethral diverticulum demonstrates normal urethra (*). There is no evidence for prolapse, with all of the pelvic organs located above the pubococcygeal line.

B: Image of same patient obtained at maximal strain demonstrates a cystourethrocele (c) as well as hypermobility of urethra (*). (Provided by G. Bennett)

Dr. Genevieve L. Bennett and colleagues from New York University Medical Center retrospectively identified from their database 99 women (mean 43 years) referred for urethral MRI in whom a dynamic sequence had been performed.

Indications for the MR exams included the following:

• suspected urethral diverticulum, 50

• recurrent urinary tract infection, 16

• urinary symptoms including pain or frequency, 27

• suspected periurethral mass, 4

• incontinence, 2

Patients were imaged using a 1.5T scanner and a torso phased-array coil. Sequences included sagittal dynamic TrueFisp alternating between rest and strain. Two experienced radiologists in consensus determined the presence and degree of pelvic organ prolapse.

Prolapse was graded as mild when the pelvic organs descended less than 2 cm below the pubococcygeal line, moderate when it dropped between 2 cm and 4 cm, and severe at greater than 4 cm.

Urethral hypermobility was defined as horizontal orientation of the urethra with strain (mild at less than 45°, and severe at greater than 45°).

The review revealed 12 urethral abnormalities: five urethral diverticulum, five Skene's gland abscess, one diverticulum and Skene's gland abscess, and one periurethral mass.

Five patients had pelvic organ prolapse at rest, but dynamic MR imaging found prolapse in 33 patients. Findings of prolapse included 28 urethrocele, 26 rectal descent, 24 cystocele, 24 vaginal vault prolapse, 13 rectocele, and two uterine prolapse. Urethral hypermobility was present in 24 patients.

In 27 patients with demonstrated prolapse (72.4%), no urethral abnormality was found. In six of the 12 patients with urethral abnormality (50%), prolapse was also demonstrated.

"We routinely use dynamic MR in this patient population. The sequence requires less than a minute of additional imaging time," Bennett told Diagnostic Imaging.

Researchers did not find any significant correlation between the referred reason for imaging and the findings on dynamic MRI.

Their ongoing investigation, however, is to further correlate patient symptoms and clinical findings with findings at MRI, as well as the impact of the findings on patient management.

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