Pelvic Floor Failure: MR Imaging Evaluation of Anatomic and Functional Abnormalities1
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Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights. WOMEN’S IMAGING 429 Pelvic Floor Failure: MR Imaging Evaluation of Anatomic and Functional Abnormalities1 Grazia T. Bitti, MD Giovanni M. Argiolas, MD Pelvic floor failure is a common disorder that can seriously jeopar- Nicola Ballicu, MD dize a woman’s quality of life by causing urinary and fecal inconti- Elisabetta Caddeo, MD nence, difficult defecation, and pelvic pain. Multiple congenital and Martina Cecconi, MD acquired risk factors are associated with pelvic floor failure, includ- Giovanna Demurtas, MD ing altered collagen metabolism, female sex, vaginal delivery, meno- Gildo Matta, MD pause, and advanced age. A complex variety of fascial and muscular M. Teresa Peltz, MD lesions that range from stretching, insertion detachment, denerva- Simona Secci, MD tion atrophy, and combinations of pelvic floor relaxation to pelvic Paolo Siotto, MD organ prolapse may manifest in a single patient. Thorough preop- erative assessment of pelvic floor failure is necessary to reduce the Abbreviations: ATFP = arcus tendineus fasciae rate of relapse, which is reported to be as high as 30%. Magnetic pelvis, ATLA = arcus tendineus musculi levatoris ani, FSE = fast spin-echo, PCL = pubococcygeal resonance (MR) imaging of the pelvic floor is a two-step process line, SSFSE = single-shot fast spin-echo that includes analysis of anatomic damage on axial fast spin-echo RadioGraphics 2014; 34:429–448 (FSE) T2-weighted images and functional evaluation using sagittal Published online 10.1148/rg.342125050 dynamic single-shot T2-weighted sequences during straining and defecation. This article presents high-resolution FSE T2-weighted Content Codes: MR images that permit detailed assessment of anatomic lesions and 1From the Department of Diagnostic Imaging, briefly describes pelvic floor pathophysiology, associated clinical Azienda G. Brotzu, Piazza A. Ricchi 1, 09134 Cagliari, Italy. Presented as an education ex- symptoms, and patterns of dysfunction seen with dynamic MR im- hibit at the 2011 RSNA Annual Meeting. aging sequences. MR imaging is a powerful tool that enables radi- Received April 4, 2012; revision requested July 17; final revision received August 6, 2013; ac- ologists to comprehensively evaluate pelvic anatomic and functional cepted September 4. For this journal-based SA- abnormalities, thus helping surgeons provide appropriate treatment CME activity, the authors, editor, and review- and avoid repeat operations. ers have no financial relationships to disclose. Address correspondence to G.T.B. (e-mail: ©RSNA, 2014 • radiographics.rsna.org [email protected]). SA-CME LEARNING OBJECTIVES FOR TEST 5 Introduction After completing this journal-based SA- Pelvic floor failure is a common disorder that affects 23.7% of CME activity, participants will be able to: women in the United States, with a prevalence of 9.7%–49.7% that ■■Recognize the clinical signs and imag- ing appearances of fascial disruptions of increases with age (1). One in nine women will undergo an invasive the pelvic floor. procedure for treatment of urinary incontinence or pelvic organ ■■Identify muscular damage associated prolapse, with 30% requiring additional surgery for symptom recur- with pelvic floor dysfunction at MR im- rence by 80 years of age (2). Furthermore, the prevalence of pelvic aging. floor disorders is predicted to increase substantially given the chang- ■■Describe MR imaging findings of ing demographics of Western countries (3). Pelvic floor dysfunction pelvic floor damage and dysfunction in may manifest with urinary tract symptoms (stress and urge inconti- patients with stress urinary incontinence, bladder outlet obstruction, and obstruct- nence, straining to void, and positional voiding maneuvers), sexual ed defecation syndrome. symptoms (difficult intercourse and dyspareunia), and bowel symp- See www.rsna.org/education/search/RG toms (fecal incontinence, difficult defecation, and rectal prolapse). General symptoms include pelvic pain and discomfort (4). 430 March-April 2014 radiographics.rsna.org Figure 1. Diagram shows the pathophysiology of pelvic floor failure. The mechanisms involved in pelvic floor failure surgery. Complementary physiologic testing (eg, are only partially understood. Multiple congenital urodynamic evaluation, anorectal manometry, and acquired factors may exist in a single patient and electromyography) (9) is invaluable for as- (Fig 1). Urinary incontinence and pelvic organ sessing pathophysiology (smooth and striate prolapse show a genetic predisposition to abnor- muscle function and sensitivity impairment) but mal extracellular matrix remodeling due to altered is inadequate for planning a surgical strategy. collagen and elastin metabolism (5). Female sex, Conventional proctography has been used menopause, and advanced age are the main risk since 1984 (10) and is still extensively used (11). factors; obesity, pregnancy, and parity cause in- It requires opacification of the rectum with a creased abdominal pressure and reduced muscle dense barium preparation, urinary bladder cath- tone. Vaginal delivery can be associated with vari- eterization for contrast medium instillation, and ous muscular, ligamentous, and osseous lesions, small bowel opacification with an orally admin- including muscle tearing and edema, bone mar- istered barium solution the night before the test. row edema, and pubic bone fracture (6). Chronic The advantages of proctography are its reduced straining due to constipation or chronic obstructive cost, the wide availability of conventional radi- pulmonary disease may cause repetitive trauma to ography and fluoroscopy, and the physiologic as- the pudendal nerve and lead to pudendal neuropa- sessment provided because the patient is in a sit- thy (7). Previous pelvic surgery, especially hysterec- ting position. The disadvantages are the radiation tomy, may result in anatomic damage with disrup- dose and the fact that anatomic assessment of the tion of the pubovesical and rectovaginal fasciae. pelvic floor is not provided. A recent study has identified an oversized pelvic Magnetic resonance (MR) imaging proctogra- outlet as an additional risk factor (8). phy was introduced in 1993 (12) and is increas- Evaluation of women with pelvic floor failure ingly used. High-resolution fast spin-echo (FSE) requires a comprehensive approach that includes T2-weighted imaging provides optimal natural clinical assessment, physiologic testing, and contrast of soft tissues; muscular and fascial in- counseling about conservative versus surgical juries as well as pelvic organ abnormalities can treatment. Clinical evaluation based on detailed be assessed. However, imaging of the rectum physical, neurologic, and digital rectal examina- and optionally the vagina requires contrast agent tion is the cornerstone of diagnosis. However, administration. Dynamic MR proctography with clinical examination is limited in several ways: interactive T2-weighted single-shot FSE (SSFSE) (a) it can lead to underestimating or misdiagnos- sequences of the pelvic floor at rest and during ing the site of prolapse; (b) it does not permit straining and defecation enables real-time evalu- assessment of evacuation disorders; and (c) it ation of patterns of dysfunction (eg, descending cannot detect a peritoneocele, a finding that indi- perineum syndrome, rectal prolapse, an enterocele cates the need for abdominal rather than vaginal or cystocele, and genital prolapse). Examination is RG • Volume 34 Number 2 Bitti et al 431 usually performed in a closed-magnet MR imag- The pelvic floor has traditionally been de- ing unit by using a supine patient position. The scribed as consisting of three compartments that results of one study showed no major disadvantage are referred to as the anterior, middle, and pos- of examinations performed in a closed-magnet terior compartments. This distinction artificially MR imaging unit compared with those performed reflects the fact that different medical specialists in an open-magnet MR imaging unit with the pa- (ie, urologists, gynecologists, and general sur- tient in a sitting position (13). However, because geons) are involved in the treatment of each com- imaging performed during defecation is necessary partment. However, this approach ignores the for adequate evaluation of functional abnormali- complexity of pelvic floor failure, which is usually ties (14), the nonphysiologic supine patient posi- generalized; therefore, the three compartments tion is considered the main drawback of using a should be assessed simultaneously. Optimally, pa- closed-magnet MR imaging unit. tients should be evaluated by a team of specialists that includes a radiologist. MR Imaging Examination Because anatomic descriptions of the pelvic Patients are thoroughly instructed about the MR floor in the radiologic literature are at times imaging examination, reassured about privacy, confusing, we use descriptions of pelvic anatomy and encouraged to comply with the procedure. cited in the most recent authoritative anatomic Ultrasound gel (100 mL) warmed to body tem- literature (16–18). The pelvic floor is composed perature is instilled in the rectum, and 5 mL may of three layers, listed from cranial to caudal: be introduced in the vagina. The patient is loosely (a) the endopelvic fascia, which wraps and gives wrapped in a waterproof incontinence pad and support to the pelvic organs