SUFU 2018: Imaging in Female Pelvic Medicine & Reconstructive Surgery - Ultrasound and MRI

Austin, TX ( Dr. A. Lenore Ackerman highlights several ultrasound modalities employed in female pelvic medicine & reconstructive surgery (FPMRS) which include, transperineal, introital, endoanal, transabdominal, and transvaginal.  The technology now exists to construct 3D reconstructions as well.  Ultrasound (US) can also be used for interventional procedures.  A common use of US is for the preoperative evaluation for pelvic surgery, in order to rule out intra abdominal pathology and determine uterus size. It is less commonly used to evaluate for vaginal masses or cystic lesions (urethral diverticulum, skenes gland cyst, gartners duct cyst). 

MRI is a better technology for this, but if contraindicated for any reason, US can be employed.   Clinicians are able to use US to evaluate after placement of a bulking agent, to assess for correct placement, abscess formation.   US is also used to evaluate alternative pathologies for pelvic pain/LUTS, have suspicion for distal ureteral stones or ureteroceles.  Dr. Ackerman describes how US can be used to detect an occult inguinal hernia.  Have concern for this pathology if the patient has pain unrelated to urination, is aggravated by physical exertion, the pain is worse with palpation of ring, or associated with transient neurological symptoms.   Endoanal US is used for the evaluation of fecal incontinence, however, the accuracy of predicting surgical outcomes remains uncertain.  For translabial/transperineal US, the patient is in lithotomy position, with a semi-full bladder.  The operator then places the transducer on labia and perineum.  This is done to visualize the anterior vaginal wall; one can determine if a cystourethrocele is present vs a  cystocele with an intact rectovesical angle.  The clinician can visualize posterior wall as well as evaluate apical prolapse, detect for an enterocele.  Dr. Ackerman discussed the utility of US in evaluating SUI; bladder neck funneling is common in women with SUI, but also can be seen in asymptomatic women, too.  Because of this, the International federation of gynecology and obstetrics determined the only useful application of US in the evaluation of urinary incontinence is the measurement of the post void residual.  There is dynamic transrectal US available for the visualization of POP, as the patient can be placed in a more normal physiologic position, which is an advantage of this imaging modality.  For imaging prolapse, MRI is probably the best imaging for true anatomic representation, but sometimes it is difficult to obtain for older patients.  US is cheaper but operator dependent.  Finally, US is very useful for visualization for mesh in mesh complications, especially to visualize the vaginal portion of the mesh.  US is superior to MRI for this.  Can use 3D reconstruction for good visualization of neighboring structures. Novel applications of US in lower urinary tract function.  Bladder wall thickening- a possible surrogate for detrusor overactivity? Overall, very low sensitivity and specificity.  Use US for female sexual dysfunction.  There are reports of use for doppler in women for clitoral artery, similar to penile doppler US in men.

Dr. Steven J. Weissbart discussed the role of MRI in FPMRS.  He highlights the use of MRI for POP and urethral diverticuli.  MRI can be a useful adjunct to evaluate the pelvic floor and identify all pelvic floor defects, using both static and dynamic views.  Currently, there is a lack of consensus on imaging protocol and reporting.  Recently, a review of standardization imaging protocol/reporting scheme was performed in Europe. 

They concluded that there are numerous indications for MRI for the pelvic floor, but most commonly performed for recurrent POP or rectal outlet obstruction.  They recommend that before imaging begins, it is important to instruct the patient how to squeeze her pelvic floor, bear down, and evacuate until empty.  MRI imaging is most commonly performed with the patient in the supine position with knees elevated.  The patient should be provided a diaper/pad and the rectum is distended with gel.  Imaging is obtained at rest, then dynamic imaging obtained in 3 different planes.  Dr. Weissbart notes that reporting may vary by specialty and indication.  He advocates for the use of the pubococcygeal line to grade/stage the degree of POP, as it has the highest inter- and intra-observer reliability.   The anterior compartment reference point used is the inferior bladder base, the middle compartment reference point is the anterior cervical lip or vaginal vault, and the posterior compartment reference point is the anorectal junction.  Pelvic floor relaxation/descent is measured by the HMO system, as pelvic floor relaxation is a separate entity from POP.  He describes the H line as the distance from the pubis to posterior anal canal and the levator hiatus width.  The M line is the distance of the levator plate descent from PCL during straining.  The HMO system for MRI also has its own grading system to show degree of relaxation/descent. 

Dr. Weissbart describes how it is possible to see urethral hypermobility on dynamic MRI as well as how the anorectal angle changes during evacuation and rest.  MRI is useful to see structural defects in urethral, vaginal, and anal support systems.  There is currently ongoing research regarding MRI and pelvic floor disorders.  He then discussed the use of MRI to visualize urethral diverticuli.  Urethral diverticuli prevalence is estimated anywhere from 1-5%.   There are many imaging modalities available to visualize them, but MRI is ideal because of its superior soft tissue resolution. They typically appear hyperintense on T2, often in a posterolateral location.  The ostium is often able to be visualized as well.  If the patient has a filling defect of the diverticulum, the clinician should have suspicion for a malignant process, i.e. adenocarcinoma of the diverticulum.  Skenes gland cysts are also able to be visualized with MRI, and often appear in a more distal location adjacent to the urethra, with a teardrop appearance, but no os visualized.  Dr. Weissbart concluded that MRI is a very useful diagnostic imaging modality for FPRMS, but future research is needed to define further utility. 

Presented by: A. Lenore Ackerman, MD, PhD - Ultrasound, Steven J. Weissbart, MD - MRI

Written by: Cristina Palmer, DO. Female Urology, Pelvic Reconstruction, Voiding Dysfunction Fellow, Department of Urology, UC Irvine Medical Center, Orange, California at the Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction Winter Meeting (SUFU 2018), February 27-March 3, 2018, Austin, Texas