Imaging of the pelvic floor: Ultrasound and MRI

1. Imaging of the pelvic floor:Ultrasound and MRI Dr Bruce AllenHorizon Radiology Acknowledgement to Dr Hans Dietz and Dr Jenny Kruger

2. Clinical application of Pelvic floor imaging • Pelvic floor muscles involved in: • Maintenance of continence • Support of the organs of the pelvis • Vaginal delivery • Failure of these muscles increases risk of: • Urinary and fecal incontinence, • Prolapse of the organs of the pelvis, • Perineal pain and dyspareunia.

3. Ultrasound imaging • Cost effective • Do not need expensive machines to do basic imaging • Ultrasound is highly operator dependant • Not difficult to learn • Real time, functional studies easy • MRI • Expensive • Images are easier to understand • Functional studies difficult.

4. 2D imaging - Ultrasound • Until recently 2D ultrasound scanning only methodology used define pathology and normal function of pelvic floor • Abdominally, transvaginal or translabial • Descent of bladder neck, uterus and rectal ampulla during a valsalva • Transperineal ultrasound useful biofeedback measure for patients • Image is in mid-sagittal plane • $12,000 machine.

5. Translabial 2D Ultrasound • Patient is supine, bladder empty ( or standardized filling) • Knees flexed, feet on the table • Transducer covered in glove/condom for hygiene • Placed fairly firmly on the perineum in the mid sagittal orientation.

6. Ultrasound Anatomy

7. Typical 2D image of the pelvic floor muscles urethra cranial

8. MRI: Sag midline, normal anatomy • Bony landmarks • 20 mins scan time • Anatomy

9. Pelvic floor functional assessment • Training • Contraction • Valsalva

10. Pelvic floor muscle contraction Contraction assess: 1. Narrowing of the hiatus in the AP diameter 2. Movement of the bladder neck 3. Strength of the PF muscle

11. Contraction: Bladder neck

12. Valsalva: BND

13. Effective valsalva manouevre • Valsalva assess: • Descent of bladder, uterus, rectum. Urethral rotation. • Development of cystocele, prolapse or rectocele • Width of hiatus in the AP diameter

14. MRI: Valsalva. Cystocoele • Functional: • 4 min per sequence • Valsalva • defaecation • (training)

15. 2D imaging • Measurements of bladder neck descent and urethral rotation. 2D Imaging Ultrasound images showing measurement of bladder neck descent and urethral rotation. Bladder neck descent (BND)= x-r –x-s. (Dietz et al 2004)

16. Clinical use of 2D ultrasound • Still widely used • Bladder, uterine and rectal descent. • Bo, K. and M. Sherburn, Evaluation of female pelvic-floor muscle function and strength. Physical therapy, 2005. 85(3): p. 269-82, Mar. • Abdominal ultrasound • Athanasiou, S., et al., Direct imaging of the pelvic floor muscles using two-dimensional ultrasound: a comparison of women with urogenital prolapse versus controls.BJOG: An International Journal of Obstetrics and Gynaecology, 2007. 114(7): p. 882-888. • Endovaginal probe • Costantini, S., et al., Perineal ultrasound evaluation of the urethrovesical junction angle and urethral mobility in nulliparous women and women following vaginal delivery. Int Urogynecol J Pelvic Floor Dysfunct, 2005. 16(6): p. 455-9. • Transperineal ultrasound • Dietz, H., Pelvic Floor Ultrasound. Current Medical Imaging Reviews, 2006. 2: p. 271-290. • Dietz, H., B. Haylen, and J. Broome, Ultrasound in the quantification of female pelvic organ prolapse. Ultrasound in Obstetrics and Gynecology, 2001. 18: p. 511-514.

17. 3D ultrasound imaging • 3D ultrasound widely used in obstetric scanning so equipment is now readily available • $100,000 – $250,000 • Acquisition of volume images allow access to the ‘axial’ plane – previously domain of magnetic resonance imaging.

18. Protocol for 3D pelvic floor imaging • Translabial imaging: • Imaged supine after voiding • Transducer ‘sits’ on the perineum mid-sagittal orientation • Mid-sagittal image on the screen • Symphysis pubis reference point – during movement • Methods highly reproducible (Guaderrama, Yang, Dietz ).

19. 3D US pelvic floor imaging – levator hiatus Voluson 730 expert system. (Dietz et al 2005)

20. MRI: normal axial anatomy

21. 3D pelvic floor ultrasound – assessing function • Levator hiatus: • ‘plane of minimal dimensions’ • Smallest distance from the inferior edge of the symphysis pubis to the anal rectal angle • Levator hiatal area bounded by the symphysis pubis anteriorly, anal rectal angle posteriorly, puborectalis/ pubococcygeus laterally. • Hiatal area measures pelvic floor function • Rest • Maximum pelvic floor muscle contraction • Maximum valsalva • (Training).

22. Normal 3D Pelvic Floor

23. 3D imaging: hiatal measurement A mid-sagittal image. Line indicates plane of minimal dimensions B corresponding ‘axial’image showing entire levator hiatus

24. Normal Contraction of the hiatus

25. Ballooning of the hiatus on Valsalva

26. Avulsion: Ultrasound. Unilateral

27. Avulsion. MRI. Large unilateral

28. Avusion: Ultrasound. Bilateral

29. MRI ………………….……….. Ultrasound

30. Conclusions • Translabial ultrasound 2D / 3D /4D • Function and anatomy • effective, easy, low cost method for assessment of the PF • Used to confirm/or not the digital diagnosis of PF dysfunction • Biofeedback training • MRI • Anatomy (and function)

31. Effective valsalva manouevre

32. Hiatal measurements at rest