Wo m e n ’s I m a g i n g • R ev i ew
Woodfield et al.
Imaging Pelvic Floor Disorders
Women’s Imaging
Review
W O M E N ’S
IMAGING
Courtney A. Woodfield1,2,3
Saravanan Krishnamoorthy4
Brittany S. Hampton2,5
Jeffrey M. Brody 1,2,3
Woodfield CA, Krishnamoorthy S, Hampton BS,
Brody JM
Imaging Pelvic Floor Disorders:
Trend Toward Comprehensive MRI
OBJECTIVE. The purpose of this article is to review the relevant anatomy and sonographic, fluoroscopic, and MRI options for evaluating patients with pelvic floor disorders.
CONCLUSION. Disorders of the pelvic floor are a heterogeneous and complex group of
problems. Imaging can help elucidate the presence and extent of pelvic floor abnormalities.
MRI is particularly well suited for global pelvic floor assessment including pelvic organ prolapse, defecatory function, and pelvic floor support structure integrity.
D
Keywords: fluoroscopy, incontinence, MRI, pelvic floor,
pelvic organ prolapse, ultrasound
DOI:10.2214/AJR.09.3670
Received September 15, 2009; accepted after revision
December 9, 2009.
1
Department of Diagnostic Imaging, Rhode Island
Hospital, 593 Eddy St., Providence, RI 02903. Address
correspondence to C. A. Woodfield (courtneywoodfield@yahoo.com)
2
The Warren Alpert Medical School of Brown University,
Providence, RI.
3
Department of Diagnostic Imaging, Women and Infants
Hospital, Providence, RI.
4
Department of Diagnostic Radiology, Yale-New Haven
Hospital, New Haven, CT.
5
Department of Urogynecology, Women and Infants
Hospital, Providence, RI.
CME
This article is available for CME credit.
See www.arrs.org for more information.
AJR 2010; 194:1640–1649
0361–803X/10/1946–1640
© American Roentgen Ray Society
1640 isorders of the pelvic floor generally refer to the problems of urinary incontinence, fecal incontinence, and pelvic organ prolapse
and affect an estimated 23.7% of women in the
United States [1]. Approximately 10–20% of
these patients are symptomatic and by the age
of 70 years, an estimated 1 in 10 undergo pelvic
floor surgical repair. In addition, over the next
30 years, the population of women over the age
of 60 years is expected to increase at a higher
rate than the general population, resulting in a
projected 45% increase in the demand for all
services related to treating patients with pelvic
floor disorders [2]. This demographic shift also
may translate into an increased demand for imaging of these patients.
Although pelvic floor disorders are relatively
common conditions, the development of these
disorders is often a complex and multifactorial
process. Weakness, tears, or both of the structures that support the pelvic organs (i.e., the
pelvic fascia, ligaments, and levator ani muscles) variably contribute to increased pelvic organ mobility; to prolapse; and, ultimately, to a
variety of symptoms ranging from pelvic pain
and pressure to urinary and fecal incontinence,
urinary and fecal retention, and defecatory dysfunction. There are numerous risk factors for
developing a pelvic floor disorder, although the
greatest risk factor is female sex. Additional
risk factors include but are not limited to increasing age, parity, prior pelvic surgeries, and
chronic increased intraabdominal pressure [3].
Evaluation of patients with pelvic floor
complaints begins with a thorough history
and physical examination, but the degree and
presence of pelvic organ prolapse may not always be apparent on clinical examination [4].
Furthermore, surgical correction of pelvic
floor disorders is a common treatment plan,
and accurate preoperative assessment of the
entire pelvis is important to guide an optimal
surgical repair in an effort to avoid the need
for repeat surgery [5, 6]. Therefore, many patients benefit from further assessment with adjunctive tests, including imaging.
There are a variety of options for imaging these patients including ultrasound, fluoroscopy, and MRI examinations. This article will review the anatomy and imaging of
patients with pelvic floor disorders with an
emphasis on the use of a comprehensive MR
examination to assess pelvic organ prolapse,
defecatory function, and the integrity of pelvic floor support structures.
Pelvic Floor Anatomy
The pelvic floor is a complex 3D support
structure for the pelvic organs. From craniad to caudad, the main support structures
are the endopelvic fascia and ligaments that
form from fascial condensations, the pelvic
diaphragm, and the urogenital diaphragm.
Support of the pelvic structures depends on
the interplay between the fascia and ligaments and the levator ani muscles. Weakness
of one of the structures may be compensated
for by the others but will predispose to eventual pelvic floor disorders.
Endopelvic Fascia and Ligaments
The anatomy of and terminology for the
endopelvic fascia and ligaments, particular-
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Imaging Pelvic Floor Disorders
ly with regard to visibility on imaging, are
still under investigation [7–17]. In addition,
the endopelvic fascia is not a true fascia on
histology and may be better described as endopelvic connective tissue. However, the term
“endopelvic fascia” is still in general use and
refers to the tissue plane that attaches to the
bony pelvis and covers the levator ani muscles and pelvic viscera in a continuous sheet
[18]. This fascia is referred to as the pubocervical fascia between the bladder and the vagina and as the rectovaginal fascia between
the vagina and rectum. The fascia extending from the cervix to the pelvic sidewall is
termed the “parametrium” and superiorly it
forms the cardinal and uterosacral ligaments
[19]. The paracolpium is the fascia extending
from the vagina to the pelvic sidewall.
Lateral condensations of the fascia unite
to form the arcus tendineus, which provides
lateral pelvic organ support and a site of attachment for the levator ani muscles. The
pubocervical fascia also extends to the arcus tendineus laterally and the pericervical
ring superiorly. The rectovaginal fascia extends to the perineal body inferiorly and to
the arcus tendineus laterally and unites with
the uterosacral ligaments superiorly. Additional supportive ligaments of the pelvic
floor include the periurethral, paraurethral,
and pubourethral ligaments, which provide
support to the urethra and bladder neck [12,
14, 17] (Fig. 1).
Pelvic Diaphragm
The pelvic diaphragm is composed of four
muscular groups, the ischiococcygeus muscle and the levator ani, which is composed
of the puborectalis, pubococcygeus, and iliococcygeus, muscles. These muscles are an
integral part of the pelvic floor and together provide continuous tone. The ischiococcygeus muscle is located posterior to the levator
ani and extends from the ischial spines to the
lateral margins of the sacrum and coccyx.
The puborectalis muscle forms a “U” arising
from the pubic bones anteriorly and forming a sling around the rectum (Figs. 2A and
2B). The iliococcygeus originates from the
arcus tendines along the lateral pelvic sidewalls and extends posterior to the rectum, in
a horizontal fashion, to insert on the coccyx
(Fig. 2C). The pubococcygeus muscle also
has a horizontal orientation, arising from the
superior ramus of the symphysis pubis and
inserting on the arcus tendineus and coccyx
[8]. This muscle also has attachments to the
vagina and the perineal body [8].
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Urogenital Diaphragm
The most caudal layer of the pelvic floor
is the urogenital diaphragm (Fig. 2D). This
diaphragm is composed of connective tissue
and the deep transverse peroneus muscle.
The diaphragm runs horizontally between
the ischial rami and extends to the perineal
body and external anal sphincter (EAS)
(Figs. 2B, 2D, and 2E). The perineal body is
located between the anal canal and the vaginal introitus and is also referred to as the
central tendon of the perineum and is the site
of attachment for many structures including
the endopelvic fascia, the EAS, the urogenital diaphragm, the bulbocavernosus muscle,
and the puborectalis muscle [20].
Pelvic Floor Compartments
For the purposes of evaluating and describing pelvic floor disorders, the pelvis is
divided into three compartments: an anterior compartment containing the bladder and
urethra, a middle compartment containing
the uterus and cervix or the vaginal cuff in
women who have undergone a hysterectomy, and a posterior compartment containing
the rectum and anal canal. Patients can have
symptoms and pelvic floor findings that involve one or more compartments.
In the anterior compartment, loss of fascial and ligamentous support to the urethra
and bladder can allow urethral hypermobility and ultimately bladder prolapse, which is
referred to as a cystocele. Patients may present with feelings of a vaginal bulge. Hypermobility of the urethra also frequently leads
to stress urinary incontinence, and kinking
at the vesicourethral junction can result in
urinary retention.
In the middle compartment, abnormalities of the pubocervical fascia, parametrium,
paracolpium, or uterosacral ligaments allow
mobility and descent of the uterus, cervix,
or vaginal cuff, creating a sensation of vaginal bulge, and may contribute to voiding and
defecatory dysfunction. Uterine prolapse is
also referred to as procidentia and vaginal
prolapse, as a vaginocele.
In the middle and posterior compartments,
defects of the rectovaginal fascia permit descent of peritoneal contents between the vagina and rectum as well as bulging of the rectal wall, which can again create a swelling
sensation, and be a cause of either fecal incontinence or obstructive defecation. Rectal bulges are also referred to as rectoceles.
Atrophy or defects of the levator ani muscle
can result in a pelvic diaphragm that is un-
Fig. 1—58-year-old woman with urinary
incontinence. Axial T2-weighted turbo spinecho image at level of mid urethra shows intact
pubourethral ligaments (arrows).
able to compensate for weakened fascia and
ligaments, and ultimately lead to global descent of the pelvic organs and urinary or defecatory dysfunction.
The term “prolapse” is commonly used to
describe any degree of downward pelvic organ movement. However, by definition prolapse refers to complete organ eversion. To
remain consistent with most prior publications, we are using “prolapse” in its more
general form in this article to describe any
degree of pelvic organ descent, except in the
posterior compartment where a distinction
is more commonly made between true rectal prolapse (invagination and eversion of the
rectum) and rectal descent without eversion
due to pelvic floor weakness.
Imaging
Conventional imaging techniques for patients with pelvic floor symptoms include ultrasound evaluation of the bladder and anal
sphincter, urodynamic testing with or without voiding cystourethrography, and evacuation proctography or cystocolpodefecography. More recently, there has been increasing
interest and research in the use of MRI to
evaluate patients with pelvic floor disorders.
Ultrasound
Ultrasound may be used to further evaluate patients with symptoms of urinary incontinence or retention and fecal incontinence.
Transabdominal, transvaginal, endoanal,
transperineal, and 3D techniques can be used
to evaluate the pelvic floor sonographically.
Ultrasound evaluation of the pelvic floor has
the advantages of being readily available and
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Woodfield et al.
A
B
D
C
E
Fig. 2—45-year-old woman with chronic constipation. MRI reveals normal-appearing levator ani and anal sphincter muscles.
A, Axial T2-weighted turbo spin-echo (TSE) image at level of anorectal junction shows intact puborectalis muscle (arrows) forming sling around rectum (R). Note right
puborectalis muscle is thinner than left.
B, Coronal T2-weighted TSE image at level of rectum shows relationship between internal anal sphincter (arrowheads), external anal sphincter (black arrows), and
puborectalis muscle (white arrows).
C, Coronal T2-weighted TSE image at level of rectum shows normal iliococcygeus muscles (arrows) with upward convexity.
D, Coronal T2-weighted TSE image at level of rectum shows urogenital diaphragm (white arrows) as most caudal layer of pelvic floor with attachment to external anal
sphincter (black arrows). Note right side of diaphragm is thinner than left. This difference in thickness was attributed to atrophy rather than volume averaging given that
asymmetry was contiguous on subsequent images.
E, Axial T2-weighted TSE image at level of anal canal illustrates normal internal (arrowhead) and external (arrows) anal sphincter muscles.
relatively easy to perform, without the use of
ionizing radiation. However, the transducer
can compress pelvic structures such as the
urethra, bladder, and vaginal canal, thereby
resulting in inaccurate assessment of organ
morphology and position. Ultrasound’s confined field of view also limits global sonographic assessment of the pelvic floor.
In patients with urinary incontinence or
retention, pre- and postvoid bladder volumes
can be readily calculated using transabdominal ultrasound [21]. The morphology of the
bladder wall and mobility at the urethrovesical junction can also be assessed sonographically [22–24]. Urethral pressure measurements on urodynamic testing reportedly
1642
correlate with the calculated urethral volume
on transvaginal ultrasound [25]. Ultrasound
has also been used to evaluate patients after
they have undergone treatment of urinary incontinence. Synthetic implants, such as suburethral slings, surgical mesh, and periurethral injections, can all be readily visualized
sonographically [26–28].
Endoanal ultrasound can be used to evaluate the integrity of the internal anal sphincter
(IAS) and the EAS muscles in patients with
fecal incontinence. The mucosa and submucosa of the anal canal are usually hyperechoic. The normal IAS is uniformly hypoechoic and is 2–3 mm in thickness. The normal
EAS is more heterogeneous in echotexture
and is variable in thickness (Fig. 3). Anal
sphincter defects appear as muscular interruptions, and ultrasound has reported sensitivities and specificities up to 90% for these
findings [29, 30] (Fig. 4).
More recently, sonographic evaluation of
pelvic organ prolapse has been described
with the use of 3D and 4D ultrasound. With
the pubic symphysis as a landmark, the transducer is positioned in a mid sagittal orientation at the level of the vaginal introitus. At
least a 70° volume field of view is needed to
visualize the urethra, vagina, anorectum, and
puborectalis at rest. Real-time acquisitions of
3D cine loops are then obtained during various maneuvers including rest, squeeze, and
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Imaging Pelvic Floor Disorders
strain. Visualization of organ prolapse and
of avulsion of the puborectalis muscle during stress has been reported [31, 32].
The role of ultrasound in evaluating pelvic
organ prolapse is still under investigation. In
a study of 145 women with pelvic organ prolapse, Dietz et al. [33] found that translabial ultrasound had good correlation with the
clinical staging of prolapse in all three compartments. However, in a more recent study
of 31 women with obstructed defecation,
translabial ultrasound had poor agreement
with evacuation proctography in the detection of rectoceles, and rectal intussusception,
and true rectal prolapse [34].
Fluoroscopy
Several fluoroscopic examinations can
be used to assess patients with pelvic floor
symptoms including voiding cystourethrography (VCUG), with or without urodynamic testing; evacuation proctography; cystoproctography; and cystocolpoproctography.
The advantages of using fluoroscopy to evaluate patients with pelvic floor abnormalities include the ability to image patients in
more physiologic standing or seated positions, study availability, and the relative ease
of study performance. The disadvantages include the more invasive nature of fluoroscopic studies, which require organ opacification
for visualization; the inability to simultaneously evaluate all three pelvic compartments;
and the use of ionizing radiation.
Voiding Cystourethrography
VCUG is primarily used to detect cystoceles in patients with a history of urinary incontinence. After filling the bladder with iodinated contrast material, patients are imaged
in the lateral standing position during rest,
stress, and voiding to detect maximal bladder descent. The mobility of the urethrovesical junction and other coexisting conditions
such as urethral diverticula and vesicoureteral reflux can also be seen [35, 36]. VCUG
has a reported accuracy of 65% for detecting urethral diverticula and 58%, compared
with the clinical Q-tip test, for diagnosing
urethral hypermobility [37, 38]. Evaluation
of detrusor instability in patients with symptoms of urge urinary incontinence requires
assessment of urodynamics [39].
Evacuation Proctography
Evacuation proctography, also termed “defecography,” refers to the fluoroscopic assessment of rectal evacuation and prolapse. The
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Fig. 3—50-year-old woman with fecal incontinence.
Transverse endoanal ultrasound image at level of
mid anal canal shows normal hypoechoic internal
(arrowheads) and more heterogeneous external
(arrows) anal sphincter muscles. (Courtesy of
Division of Colon and Rectal Surgery, Rhode Island
Hospital, The Warren Alpert Medical School of
Brown University)
Fig. 4—70-year-old man with fecal incontinence.
Transverse endoanal ultrasound image at level of
mid anal canal shows anterior defect of internal anal
sphincter muscle (arrow). Edges of internal sphincter
muscle (asterisks) are shown. (Courtesy of Division of
Colon and Rectal Surgery, Rhode Island Hospital, The
Warren Alpert Medical School of Brown University)
A
B
Fig. 5—60-year-old woman with defecatory dysfunction.
A and B, Lateral evacuation proctography images obtained with patient at rest (A) and during evacuation (B)
show pelvic floor descent with anterior anorectal junction (arrowhead) located below pubococcygeal line
(dashed line). Anorectal angle is normal at rest (110°) and becomes more obtuse during evacuation (arrow, B).
Symphysis pubis (asterisk) is seen. Patient was able to evacuate rectal contrast material without difficulty.
Fig. 6—53-year-old woman with obstructed
defecation. Lateral evacuation proctography image
reveals 3.5-cm anterior rectocele (horizontal line).
Vertical line is along long axis of expected location of
anterior wall of anal canal.
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Woodfield et al.
A
B
Fig. 7—47-year-old woman with constipation and pelvic pain.
A and B, Midline sagittal T2-weighted HASTE images show reference lines: Pubococcygeal line (PCL) (black
line, A) extends from inferior symphysis pubis to last joint of coccyx (A) and midpubic line (MPL) (long white
line, B) extends along long axis of symphysis pubis (B). Perpendicular measurements from anatomic reference
points in anterior (dashed lines), middle (arrows), and posterior (short white lines) compartments are also
shown with respect to PCL and MPL.
study is primarily used to evaluate patients
with a history of constipation or defecatory
dysfunction and is a fairly straightforward and
rapid test to perform [20]. The key component
of the examination is the use of semisolid contrast material (i.e., barium suspension mixed
with a starch) to opacify the rectum. Seated
on a commode setup, the patient can then be
imaged continuously with videofluoroscopy
performed before evacuation, during evacuation, and after evacuation.
The components of a normal evacuation
proctography examination have been de-
scribed [40]. Bony landmarks in the lateral position, such as the symphysis pubis, the
ischial tuberosity, and the coccyx, have all
been used to estimate the level of the pelvic
floor and the degree of pelvic floor descent
during evacuation. Depending on the fluoroscopic equipment and technique and the patient’s body habitus, these bony landmarks
can be difficult to visualize. However, newer,
digital fluoroscopic equipment with postprocessing capabilities has enhanced visualization of these bony landmarks and may facilitate detection of pelvic floor descent [41].
Fig. 8—54-year-old woman with urinary retention.
Sagittal T2-weighted HASTE image obtained during
Valsalva maneuver reveals descent of bladder base
(arrow) 3.5 cm below both pubococcygeal line (PCL)
(dashed line) and 1.5 cm below midpubic line (MPL)
(solid line) consistent with moderate (PCL staging) or
stage 3 (MPL staging) bladder prolapse.
Fig. 9—49-year-old woman with pelvic pain and
bulge. Sagittal T2-weighted HASTE image obtained
during Valsalva maneuver reveals descent of uterus
with anterior cervical lip (white arrow) 5.0 cm
below both pubococcygeal line (PCL) (dashed line)
and 1.2 cm below midpubic line (MPL) (solid line)
consistent with moderate (PCL staging) or stage 3
(MPL staging) uterine prolapse. Also note bladder
prolapse (black arrow).
1644
Pelvic floor descent can be further quantified by measuring the distance from the chosen fixed bony landmark for the pelvic floor
to the level of the anorectal junction during
evacuation [42]. In addition, various reference
lines based on bony pelvic landmarks, including a line extending from the symphysis pubis
to the last coccygeal joint (the pubococcygeal
line [PCL]) or a line extending along the long
axis of the symphysis pubis (the midpubic line
[MPL]), can serve as lines of reference for fluoroscopic assessment of pelvic organ descent
or prolapse. The PCL is one of the more commonly reported reference lines for fluoroscopic examinations [43].
Before evacuation, the anorectal junction
should be at or above the PCL. The anorectal junction is the distally tapered point of the
rectal contrast column caused by posterior
impression of the puborectalis muscle. The
anorectal angle is the angle formed at the anorectal junction by the posterior aspect of the
distal rectum and the long axis of the anal canal. This angle is normally 90–110° at rest.
With normal complete evacuation, the pelvic
floor descends, the puborectalis and sphincter muscles relax, the puborectalis impression
on the posterior rectal wall decreases, the anorectal angle becomes more obtuse, and the
anal canal shortens and widens (Fig. 5). After evacuation, anal sphincter tone and levator
ani muscle tone increase, resulting in a more
acute anorectal angle and return of the structures to their preevacuation positions [40].
In addition to assessing rectal evacuation,
evacuation proctography can also show rectal intussusception, rectal prolapse, and rectoceles. Intussusceptions manifest as invaginations of the rectum into itself, the anal canal,
or extraanally (i.e., true, complete prolapse)
[44]. Rectoceles are most commonly directed anteriorly and are diagnosed if the anterior
margin of the rectal wall bulge is more than 2
cm anterior to a line drawn along the long axis
of the anterior anal canal [43] (Fig. 6).
Rectal intussusception, rectal prolapse, and
rectoceles are all potential reasons for difficult
rectal evacuation. Another cause of constipation is failure of the puborectalis muscle to relax during attempted evacuation, also referred
to as paradoxical contraction of the puborectalis muscle, anismus, or pelvic dyssynergy. Absent or slow rectal emptying (> 66% of rectal
contrast material not evacuated by 30 seconds)
has been reported to have up to a 90% positive
predictive value for pelvic dyssynergy [45].
Evaluation of coexisting anterior compartment and middle compartment weak-
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Imaging Pelvic Floor Disorders
ness with fluoroscopy requires opacification
of additional pelvic organs. In the middle
compartment, rectovaginal fascial defects
allow the abdominal contents to descend into
the rectovaginal space during evacuation or
strain. Large-bowel descent is referred to as
a sigmoidocele; small bowel, as an enterocele; and peritoneal fat, as a peritoneocele.
If retrograde rectal contrast medium reaches
the sigmoid colon, sigmoidoceles may be detected fluoroscopically. To reliably detect enteroceles, the small bowel can be opacified
with an oral contrast preparation 1–2 hours
before the study. Displacement of the vagina
during evacuation and strain can be shown
by opacifying the vagina with barium paste
or contrast medium mixed with ultrasound
gel [46]. Finally, to assess for weakness in
the anterior compartment, the bladder can
be catheterized, drained, and then opacified
with water-soluble contrast material. The position of the bladder at rest and during maximal strain can then be determined. The bladder base should normally remain above the
PCL. Fluoroscopic evaluation of the opacified bladder and the rectum is referred to
as cystoproctography and evaluation of the
opacified bladder, vagina, and rectum, as
cystocolpoproctography [47].
Fluoroscopic studies are often considered
the gold standard for the diagnosis of pelvic
floor abnormalities when newer techniques
are introduced because fluoroscopic studies
have been widely used for the past 20 years.
However, there is really no true gold standard
against which fluoroscopy can be compared.
Patient symptoms and clinical and surgical
findings of pelvic floor abnormalities are often variable and inconsistent. Fluoroscopic
studies have been shown to reveal more extensive pelvic floor abnormalities than physical
examination alone with high observer accuracy [48]. Fluoroscopic studies have also been
shown to alter the management of patients in
up to 40% of cases [49]. The more extensive
abnormalities detected with fluoroscopy compared with physical examination are likely, at
least partly, due to the ability to image the patient during defecation with fluoroscopy compared with only the Valsalva maneuver with
physical examination.
MRI
MRI is the newest technique used to evaluate patients with pelvic floor disorders. There
are several advantages of MRI over the more
traditional fluoroscopic and sonographic
methods: It allows relatively noninvasive, dy-
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Fig. 10—67-year-old woman with incomplete
defecation. Sagittal T2-weighted HASTE image
obtained during Valsalva maneuver reveals descent of
rectum (white arrow) 5.5 cm below pubococcygeal line
(PCL) (dashed line) and 1.2 cm below midpublic (MPL)
(solid line); these findings are consistent with moderate
(PCL staging) or stage 3 (MPL staging) rectal descent.
Also, note 4-cm anterior rectocele (long black arrow)
and mild, stage 1, bladder prolapse (short black arrow).
Fig. 11—72-year-old woman with question of
rectocele on physical examination. Sagittal T2weighted HASTE image obtained during Valsalva
maneuver reveals descent of sigmoid colon (white
arrows) into rectovaginal space. Also note rectal
descent (black arrow) and anterior rectocele (doubleheaded arrow). V = vaginal canal, R = rectum.
namic evaluation of all pelvic organs in multiple planes with high soft-tissue and temporal
resolution without the use of ionizing radiation. In addition, MRI can directly visualize
the muscular and ligamentous pelvic floor
support structures. Disadvantages of using
MRI to evaluate the pelvic floor include the
less physiologic supine positioning of patients
during imaging if an open seated magnet is
not available, higher costs, and potentially
limited radiologist experience.
Using MRI to evaluate pelvic floor disorders
may be most helpful in patients with multi-
compartment physical examination findings or
symptoms, posterior compartment abnormalities, severe prolapse, or recurrent pelvic floor
symptoms after prior surgical repair. Several
studies have shown that MRI is a useful method for diagnosing and staging pelvic organ
prolapse, with detection rates similar to fluoroscopic techniques, and that MRI is often able
to reveal more extensive organ prolapse than
physical examination alone [43, 50–52]. In a
study of 10 patients who underwent both dynamic MRI and fluoroscopic cystocolpoproctography, the MRI and fluoroscopic results
A
B
Fig. 12—37-year-old woman with chronic constipation.
A and B, Sagittal true FISP images obtained with patient at rest (A) and during evacuation (B) show normal
change in anorectal angle with evacuation, 100–145°. Also, note anal canal (arrows) is shorter and wider during
evacuation. Patient evacuated rectal contrast material without difficulty.
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Woodfield et al.
were similar. Ten rectoceles and nine cystoceles were shown on both studies. Seven enteroceles were diagnosed on fluoroscopy, one of
which was not initially seen on MRI, and two
sigmoidoceles were diagnosed on MRI, one of
which was not identified fluoroscopically [43].
In a more recent study of 50 patients with fecal
incontinence, MRI also reportedly changed the
surgical approach in 22 (67%) of 33 patients
who underwent surgery [50]. Accurate assessment of all three compartments is important to
help guide management, particularly in women considering surgical treatment.
MRI Protocol
There is no standardized protocol for MRI
of patients with pelvic floor disorders. However,
the key element of any protocol is to image the
patient during maximal strain or rectal evacuation in one or more planes. The protocol for
MRI of the pelvic floor used at Women and
Infants Hospital and the reason for performing each sequence are outlined in Table 1. Patients are asked to void immediately before the
study. They are then positioned on the MR table
on a water-resistant pad. Using 60-mL syringes,
120 mL of ultrasound gel is placed into the
rectum. The patient is then turned into the supine position and the pad is secured around
the pelvis. A wedge is placed underneath the
patient’s knees to help maximize strain maneuvers in the supine position. Imaging is then
performed with a pelvic phased-array coil,
which is positioned slightly lower than usual
to cover the proximal thighs to ensure complete coverage of pelvic organ descent.
Protocols may vary with respect to patient
positioning, pelvic organ opacification, patient
maneuvers (i.e., rest, Kegel, Valsalva, evacuation), and MR sequences and planes. Bertschinger et al. [53] reported equivalent outcomes
for patients imaged in both the seated and supine positions. Our examinations are and most
pelvic floor MR studies to date have been performed with supine imaging in a closed magnet [43, 54–56]. Sonography gel, a starch substance mixed with gadolinium, or air has been
used to opacify the rectum. In a study of 82
women who underwent supine MRI both with
and without rectal contrast material as well
as fluoroscopic cystocolpoproctography, MRI
without rectal contrast material revealed statistically fewer pelvic floor abnormalities than
MRI with rectal contrast material, which had
a performance similar to that of cystocolpoproctography [57]. Although we do not find it
necessary, ultrasound gel can be used to opacify the vaginal canal and some authors report
1646
TABLE 1: Example MRI Protocol for Patients With Pelvic Floor Disorders
Imaging
Sequence Plane
Patient
Position
HASTE
Sagittala
HASTE
Sagittala Kegel
True FISP
Sagittalb
HASTE
Slice
Thickness Field of
TR (ms) TE (ms)
(mm)
View (cm)
Matrix
Purpose
1,150
100
7
35
224 × 256 Determine resting
organ positions
1,150
100
7
35
224 × 256 Assess Kegel ability
15
2
6
30
224 × 256 Evaluate pelvic
organ prolapse,
rectal evacuation
Sagittala Valsalva
1,150
100
7
35
224 × 256 Evaluate pelvic
organ prolapse
HASTE
Coronala Valsalva
1,150
100
7
35
224 × 256 Evaluate pelvic
organ prolapse
TSE
Axial
Rest
5,640
120
4
30
300 × 384 Evaluate pelvic
support structures
TSE
Coronal Rest
5,640
120
4
30
300 × 384 Evaluate pelvic
support structures
Rest
Evacuation
Note—Examination performed on a 1.5-T closed magnet. FISP = fast imaging with steady-state free precession,
TSE = turbo spin-echo.
aImaging from femoral head to femoral head.
bTrue FISP evacuation sequence is performed before the single-shot fast spin-echo Valsalva sequence to
ensure that rectal contrast material is not lost before dynamic imaging. The true FISP sequence is a continuous
60-second acquisition along the mid sagittal slice. Acquisition time per image = 1 second.
catheterizing and filling the bladder with saline to more easily identify bladder descent
[56]. Imaging patients during rectal evacuation tends to reveal the greatest degree of pelvic organ descent. Real-time true fast imaging
with steady-state precession (FISP) sequences
reportedly show greater degrees of organ prolapse than HASTE sequences, which require a
short delay between series [58].
MRI Interpretation
Interpretation of a pelvic floor MR examination can be broken down into the assessment of three components: pelvic organ prolapse, rectal evacuation, and the pelvic floor
support structures.
Pelvic organ prolapse—Pelvic organ prolapse is best evaluated on midsagittal true
FISP dynamic evacuation sequences and
sagittal and coronal HASTE strain images
when pelvic organ descent should be greatest.
Similar to cystoproctography, to determine
the presence and extent of pelvic organ prolapse, a point of reference for rest and stress
measurements is required. Several reference
points and lines for measuring and staging
pelvic organ prolapse on MRI have been proposed. The two most commonly used lines
are a line connecting the inferior aspect of the
pubic symphysis to the last coccygeal joint,
the PCL; and a line extending caudally along
the long axis of the symphysis pubis, the MPL
[56, 59–61] (Fig. 7).
On cadaveric dissection, the MPL has been
shown to correspond to the level of the vaginal
hymen, the landmark used for clinical staging
[61]. To date, neither the PCL nor the MPL
has been shown to have better agreement with
clinical staging [62]. The choice of reference
line for MRI interpretation may be dependent
on radiologist experience and referring physician preference. At our institution, the MPL is
used to stage pelvic organ prolapse on MRI.
This reference line was chosen because the
urogynecologists at our institution, who refer
most of the patients for pelvic floor MR examinations, are more familiar with the MPL
and its staging system because it is the same
staging system they use clinically. We include
a description of the MPL and the MPL staging
system at the end of each MR report for physicians who may be less familiar this reference
line and staging system.
Once the MR reference line is chosen, staging of pelvic organ prolapse in all three compartments can be performed by measuring the
perpendicular distance from the anatomic reference point in each compartment to the reference line (Fig. 7). In the anterior compartment, the reference point is the most posterior
and inferior aspects of the bladder base. In
the apical compartment, the reference point is
the anterior cervical lip or the posterosuperior vaginal apex if the patient has undergone
hysterectomy. In the posterior compartment,
the anterior aspect of the anorectal junction
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Imaging Pelvic Floor Disorders
serves as the point of reference [43, 47, 63,
64]. The largest measurement during strain
or evacuation, defined as the measurement
farthest below the reference line or closest to
the reference line if located above the PCL or
MPL, is used to stage the presence and degree
of pelvic organ prolapse (Figs. 8–10). Staging
systems for both the PCL and MPL exist [43,
51, 53, 60, 61] (Tables 2 and 3).
Cul-de-sac defects—In addition to assessing pelvic organ prolapse, the cul-desac should also be evaluated on the evacuation and strain sequences for enteroceles,
sigmoidoceles, and peritoneoceles [43, 65].
Cul-de-sac defects are particularly challenging to diagnose and characterize on physical examination because a posterior vaginal
wall bulge could be due to any of these three
or the rectum. Because of its excellent softtissue resolution, MRI can readily diagnose
the contents of a cul-de-sac bulge without the
use of oral contrast material as would be required for fluoroscopic studies (Fig. 11).
Defecatory function—Next, defecation
can be evaluated with the dynamic midsagittal true FISP images obtained during rectal evacuation. In our facility, if the patient
is unable to evacuate the rectal contrast material on the first attempt, the sequence is repeated at least twice to ensure that the inability to evacuate contrast material is not due to
a lack of communication or effort. The same
criteria for normal defecation on evacuation
proctography can be applied to MRI. Normal
defecation on MRI is characterized by the
ability to evacuate at least some of the rectal contrast material as well as the appropriate changes in the anorectal angle (Fig. 12).
Also, similar to evacuation proctography,
MRI can reveal additional reasons for abnormal defecation including true rectal prolapse,
rectoceles, and rectal intussusception.
Intussusceptions can be difficult to detect
on MRI, and fluoroscopy has been shown to
reveal more intussusceptions than MRI. The
sensitivity for diagnosing rectal intussusception on MRI has been reported to be 70% relative to evacuation proctography [66]. However, the soft-tissue resolution of MRI may
allow better differentiation between mucosaonly intussusceptions versus full-wall-thickness intussusceptions [66]. Small rectoceles
may also be better seen on fluoroscopy.
Pelvic dyssynergia manifests on MRI as
an inability to evacuate rectal contrast material despite multiple attempts. However,
the inability to evacuate the rectal contrast
material could also be due to difficulty def-
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ecating in the supine position. In our experience, most patients are able to evacuate at
least some of the rectal contrast material in
the supine position if allowed multiple attempts (at least two to three). Assessment of
the anorectal angle during attempted defecation may help differentiate between patients
with true paradoxical contraction of the puborectalis muscle and patients who have difficulty defecating due to supine positioning.
No change in the anorectal angle or a more
acute change in the anorectal angle with attempted defecation may suggest pelvic dyssynergia, whereas a more obtuse change in
the anorectal angle may suggest difficulty
defecating supine [67].
Investigators have suggested that the diagnosis of rectal intussusception, true prolapse,
and incomplete emptying of rectoceles may
be made more confidently with evacuation
proctography than with MRI [68]. This may
be partly due to the more physiologic seated
position of patients with fluoroscopy, which
may facilitate defecation, and to radiologist
experience. However, up to 30% of patients
with rectal intussusception reportedly have
associated pelvic organ descent in the anterior, middle, or both compartments [69].
Therefore, MRI may be the first study of
choice when there are physical examination
findings or the patient has symptoms suggestive of multicompartment abnormalities.
Pelvic floor support—The third step of the
MR examination is to assess the pelvic floor
support structures. The support structures are
best visualized on the axial and coronal T2weighted turbo spin-echo (TSE) sequences.
The iliococcygeus and puborectalis muscles
are well visualized on MRI. The ischiococcygeus and pubococcygeus are typically not seen
separately, and with the use of only a pelvic
phased-array coil, the supportive ligaments
TABLE 2: Staging of Pelvic
Organ Prolapse Using
Pubo­coccygeal Line (PCL)
Stage
Criteriaa
Small prolapse
1 to < 3 cm below PCL
Moderate prolapse
3–6 cm below PCL
Large prolapse
> 6 cm below PCL
Note—Moderate prolapse and large prolapse are
usually symptomatic [50].
aDistance of inferior bladder base, anterior cervical
lip, and anterior anorectal junction from PCL.
are variably seen and the endopelvic fascia is
not directly visualized. However, there have
been several recent reports of high-resolution
MRI of cadavers and patients with endourethral and endovaginal coils to better identify
and visualize the ligaments of the pelvic floor
[10, 11, 13, 14, 16, 17].
The puborectalis muscle is best visualized in the axial plane and thinning and defects can be detected. Asymmetry of the muscle, with the right side being thinner than the
left, has been described as a normal variation
on MRI [70]. This asymmetry has been proposed to be due to variable chemical shift artifact that can make the muscle appear thicker
on the left [9]. In the coronal plane, the iliococcygeus muscle is well visualized. Normally this muscle is convex upward. Atrophy of
the muscle may result in downward convexity.
The urogenital diaphragm is also best visualized in the coronal plane [20] (Figs. 2A–2D).
The anal sphincter muscles are well visualized and can be evaluated in both the axial
and coronal planes (Figs. 2B and 2E). The
IAS is the innermost muscle and is uniformly intermediate in signal intensity on T2weighted images. The EAS is the outermost
muscle and is usually lower in signal intensity on T2-weighted images. The EAS may
TABLE 3: Staging of Pelvic Organ Prolapse Using Midpubic Line (MPL)
Criteriaa
Stage
0
> 3 cm to (TVLb – 2 cm) above MPL
1
Does not meet stage 0, but > 1 cm above MPL
2
≤ 1 cm above or below MPL
3
> 1 cm below MPL
4
Complete organ eversion
Note—Stages 2–4 are usually symptomatic. The MPL reference line and clinical pelvic organ prolapse
quantification examination use the same staging system [61].
aDistance of inferior bladder base, anterior cervical lip, and anterior anorectal junction from MPL.
bOn physical examination and sagittal MR images, total vaginal length (TVL) is the greatest vertical vaginal
measurement in centimeters from the posterior vaginal fornix to the level of the introitus in patients with a
cervix. In patients without a cervix, the measurement is made from the most superior aspect of the vaginal cuff
to the level of the introitus [74].
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Woodfield et al.
be open anteriorly or posteriorly as a normal
variation, and this finding should not be mistaken for a muscular defect [20]. Defects of
the sphincter muscles can be difficult to characterize because they are often accompanied
by low-signal-intensity fibrosis rather than
a clear muscle gap [30, 71]. MRI has been
shown to be as accurate (91%) as ultrasound
for the detection of anal sphincter defects—
in particular, for defects of the EAS—but to
be more accurate (93%) than ultrasound for
the diagnosis of sphincter atrophy [72, 73].
Visualization and evaluation of the ligamentous and fascial support of the pelvic organs with MRI are challenging and an area
of increasing clinical and research interest
[10, 11, 13, 14, 16, 17]. Using an endourethral
MR coil and high-resolution MRI, Macura et
al. [14] described at least three different ligaments that provide support to the female
urethra: the periurethral, paraurethral, and
pubourethral ligaments. Imaging with an endovaginal coil may also improve visualization
of the ligaments supporting the urethra [13].
In another recent article, El Sayed et al. [16]
described secondary signs of paravaginal fascial defects including posterior protrusion of
the bladder. Knowledge of the exact site of a
muscular, ligamentous, or fascial defect of the
pelvic floor could allow more tailored management and surgical treatment of patients.
Conclusion
Pelvic floor disorders are a common and
complex problem in which imaging plays a key
role in effective diagnosis and treatment. Ultrasound, fluoroscopy, and MRI can all be used to
evaluate the pelvic floor. Although research is
ongoing, static and dynamic MRI has the advantages of simultaneously and relatively noninvasively evaluating pelvic organ prolapse in
all three compartments, rectal evacuation, and
various pelvic floor support structures.
References
1.Nygaard I, Bradely C, Brandt D. Pelvic organ prolapse in older women: prevalence and risk factors.
Obstet Gynecol 2004; 104:489–497
2.Luber KM, Boero S, Choe JY. The demographics
of pelvic floor disorders: current observations and
future projections. Am J Obstet Gynecol 2001;
184:1496–1501
3.Bump RC, Norton PA. Epidemiology and natural
history of pelvic floor dysfunction. Obstet Gynecol Clin North Am 1998; 25:723–746
4.Maglinte DDT, Kelvin FM, Fitzgerald K, Hale DS,
Benson JT. Association of compartment defects in
pelvic floor dysfunction. AJR 1999; 172:439–444
1648
5.Nygaard IE, Kreder KJ. Complications of incontinence surgery. Int Urogynecol J 1994; 5:353–360
6.Gagliardi G, Pescatori M, Altomare DF, et al. Results, outcome predictors, and complications after
stapled transanal rectal resection for obstructed
defecation. Dis Colon Rectum 2008; 51:186–195
7.Kirschner-Hermanns R, Wein B, Niehaus S,
Schaefer W, Jakes G. The contribution of magnetic resonance imaging of the pelvic floor to the
understanding of urinary incontinence. Br J Urol
1993; 72:715–718
8.Strohbehn K, Ellis JH, Strohbehn HA, DeLancey
JOL. Magnetic resonance imaging of the levator
ani with anatomic correlation. Obstet Gynecol
1996; 87:277–285
9.Tunn R, Paris S, Fischer W, Hann B, Kuchinke J.
Static magnetic resonance imaging of the pelvic
floor: muscle morphology in women with stress
urinary incontinence and pelvic prolapse. Neurourol Urodyn 1998; 17:579–589
10.Huddleston HT, Dunnihoo DR, Huddleston PM
3rd, Meyers PC Sr. Magnetic resonance imaging
of defects in DeLancey’s vaginal support levels I,
II, and III. Am J Obstet Gynecol 1995; 172:1778–
1782; discussion, 1782–1784
11.Tan IL, Stoker J, Zwamborn AW, Entius KA,
Calame JJ, Lameris JS. Female pelvic floor: endovaginal MR imaging of normal anatomy. Radiology 1998; 206:777–783
12.DeLancey JO. Structural support of the urethra as
it relates to stress urinary incontinence: the hammock hypothesis. Am J Obstet Gynecol 1994;
170:1713–1723
13.Kim JK, Kim YJ, Choo MS, Cho KS. The urethra
and its supporting structures in women with stress
urinary incontinence: MR imaging using an endovaginal coil. AJR 2003; 180:1037–1044
14.Macura KJ, Genadry RR, Bluemke DA. MR imaging of the female urethra and supporting ligaments in assessment of urinary incontinence:
spectrum of abnormalities. RadioGraphics 2006;
26:1135–1149
15.Macura KJ. Magnetic resonance imaging of pelvic floor defects in women. Top Magn Reson Imaging 2006; 17:417–426
16.El Sayed RF, Mashed SE, Farag A, Morsy MM,
Abdel Azim MS. Pelvic floor dysfunction: assessment with combined analysis of static and dynamic MR imaging findings. Radiology 2008;
248:518–530
17.El Sayed RF, Morsy MM, El Mashed SM, AbdulAzim MS. Anatomy of the urethral supporting
ligaments defined by dissection, histology, and
MRI of female cadavers and MRI of healthy nulliparous women. AJR 2007; 189:1145–1157
18.DeLancey JOL. The anatomy of the pelvic floor.
Curr Opin Obstet Gynecol 1994; 6:313–316
19.Strohbehn K. Normal pelvic floor anatomy. Ob-
stet Gynecol Clin North Am 1998; 25:683–705
20.Stoker J, Halligan S, Bartram CI. Pelvic floor imaging. Radiology 2001; 218:621–641
21.Hartnell GG, Kiely EA, Williams G, Gibson RN.
Real-time ultrasound measurement of bladder
volume: a comparative study of three methods. Br
J Radiol 1987; 60:1063–1065
22.Quinn MJ, Beynon J, Mortensen NJ, Smith PJ.
Transvaginal endosonography: a new method to
study the anatomy of the lower urinary tract in
urinary stress incontinence. Br J Urol 1988;
62:414–418
23.Khullar V, Salvatore S, Cardozo L, Bourne TH,
Abbott D, Kelleher C. A novel technique for measuring bladder wall thickness in women using
transvaginal ultrasound. Ultrasound Obstet Gynecol 1994; 4:220–223
24.Umek WH, Obermair A, Stutterecker D, Häusler
G, Leodolter S, Hanzal E. Three-dimensional ultrasound of the female urethra: comparing transvaginal and transrectal scanning. Ultrasound
Obstet Gynecol 2001; 17:425–430
25.Digesu GA, Robinson D, Cardozo L, Khullar V.
Three-dimensional ultrasound of the urethral
sphincter predicts continence surgery outcome.
Neurourol Urodyn 2009; 28:90–94
26.Dietz HP. Ultrasound imaging of the pelvic floor.
Part II. Three-dimensional or volume imaging.
Ultrasound Obstet Gynecol 2004; 23:615–625
27.Reich A, Wiesner K, Kohorst F, Kreienberg R,
Flock F. Comparison of transobturator vaginal
tape and retropubic tension-free vaginal tape:
clinical outcome and sonographic results of a
case-control study. Gynecol Obstet Invest 2009;
68:137–144
28.Strasser H, Marksteiner R, Margreiter E, et al. Transurethral ultrasonography-guided injection of adult
autologous stem cells versus transurethral endoscopic injection of collagen in treatment of urinary
incontinence. World J Urol 2007; 25:385–392
29.Deen KI, Kumar D, Williams JG, Olliff J, Keighley MR. The prevalence of anal sphincter defects
in faecal incontinence: a prospective endosonic
study. Gut 1993; 34:685–688
30.Dobben AC, Terra MP, Slors JF, et al. External
anal sphincter defects in patients with fecal incontinence: comparison of endoanal MR imaging
and endoanal US. Radiology 2007; 242:463–471
31.Örnö AK, Herbst A, Marsál K. Sonographic characteristics of rectal sensations in healthy females.
Dis Colon Rectum 2007; 50:64–68
32.Majida M, Braekken IH, Umek W, Bø K, Saltyte
Benth J, Ellstrøm Engh M. Interobserver repeatability of three- and four-dimensional transperineal ultrasound assessment of pelvic floor
muscle anatomy and function. Ultrasound Obstet
Gynecol 2009; 33:567–573
33.Dietz HP, Haylen BT, Broome J. Ultrasound in the
AJR:194, June 2010
quantification of female pelvic organ prolapse.
Ultrasound Obstet Gynecol 2001; 18:511–514
34.Perniola G, Shek C, Chong CC, Chew S, Cartmill
J, Dietz HP. Defecation proctography and translabial ultrasound in the investigation of defecatory
disorders. Ultrasound Obstet Gynecol 2008;
31:567–571
35.Maglinte DDT, Kelvin FM, Hale DS, Benson JT.
Dynamic cystoproctography: a unifying diagnostic approach to pelvic floor and anorectal dysfunction. AJR 1997; 169:759–767
36.Kelvin FM, Maglinte DD, Hale D, Benson JT.
Voiding cystourethrography in female stress incontinence. AJR 1996; 167:1065–1066
37.Lee JW, Fynes MM. Female urethral diverticula.
Best Pract Res Clin Obstet Gynaecol 2005;
19:875–893
38.Walsh LP, Zimmern PE, Pope N, Shariat SF; Urinary Incontinence Treatment Network. Comparison
of the Q-tip test and voiding cystourethrogram to assess urethral hypermobility among women enrolled
in a randomized clinical trial of surgery for stress
urinary incontinence. J Urol 2006; 176:646–649
39.Pelsang RE, Boney WW. Voiding cystourethrography in female stress incontinence. AJR 1996;
166:561–565
40.Mahieu P, Pringot J, Bodart P. Defecography. Part I.
Description of a new procedure and results in normal patients. Gastrointest Radiol 1984; 9:247–251
41.Kelvin FM, Maglinte DDT. Dynamic evaluation of
female pelvic organ prolapse by extended proctography. Radiol Clin North Am 2003; 41:395–407
42.Bartram C. Radiologic evaluation of anorectal
disorders. Gastroenterol Clin North Am 2001;
30:55–75
43.Kelvin FM, Maglinte DDT, Hale DS, Benson JT. Female pelvic organ prolapse: a comparison of triphasic
dynamic MR imaging and triphasic fluoroscopic cystocolpoproctography. AJR 2000; 174:81–88
44.Pomerri F, Zuliani M, Mazza C, Villarejo F, Scopece A. Defecographic measurements of rectal
intussusception and prolapse in patients and in
asymptomatic subjects. AJR 2001; 176:641–645
45.Halligan S, Malouf A, Bartram CI, Marshall M,
Hollings N, Kamm MA. Predictive value of impaired evacuation at proctography in diagnosing
anismus. AJR 2001; 177:633–645
46.Altringer WE, Saclarides TJ, Dominguez JM,
Brubaker LT, Smith CS. Four-contrast defecography: pelvic “floor-oscopy.” Dis Colon Rectum
1995; 38:695–699
47.Kelvin FM, Hale DS, Maglinte DD, Patten BJ,
Benson JT. Female pelvic organ prolapse: diagnostic contribution of dynamic cystoproctography
and comparison with physical examination. AJR
1999; 173:31–37
48.Pfeifer J, Oliveira L, Park UC, Gonzales A,
Agachan
F, Wexner
Are Disorders
interpretations of
Imaging
Pelvic SD.
Floor
video defecographics reliable and reproducible?
Int J Colorectal Dis 1997; 12:67–72
49.Harvey CJ, Halligan S, Bartram CI, Holings N,
Sahdev A, Kingston K. Evacuation proctography:
a prospective study of diagnostic and therapeutic
effects. Radiology 1999; 211:223–237
50.Hetzer FH, Andreisek G, Tsagari C, Sahrbacher
U, Weishaupt D. MR defecography in patients
with fecal incontinence: imaging findings and
their effect on surgical management. Radiology
2006; 240:449–457
51.Gufler H, Laubenberger J, DeGregorio G,
Dohnicht S, Langer M. Pelvic floor descent: MR
imaging using a half-Fourier RARE sequence. J
Magn Reson Imaging 1999; 9:378–383
52.Kaufman HS, Buller JL, Thompson JR, et al. Dynamic pelvic magnetic resonance imaging and
cystocolpoproctography alter surgical management of pelvic floor disorders. Dis Colon Rectum
2001; 44:1575–1583
53.Bertschinger KM, Ketzer FH, Roos JE, Treiber K,
Marincek B, Hilfiker PR. Dynamic MR imaging of
the pelvic floor performed with a patient sitting in
an open-magnet unit versus with patient supine in a
closed-magnet unit. Radiology 2002; 223:501–508
54.Fielding JR, Giffiths DJ, Versi E, Mulkern RV,
Lee ML, Jolesz FA. MR imaging of pelvic floor
continence mechanism in the supine and sitting
positions. AJR 1998; 171:1607–1610
55.Unterweger M, Marincek B, Gottstein-Aalame N,
et al. Ultrafast MR imaging of the pelvic floor.
AJR 2001; 176:959–963
56.Lienemann A, Anthuber C, Baron A, Kohn P, Reiser M. Dynamic MR colpocystorectography assessing pelvic floor descent. Eur Radiol 1997;
7:1309–1317
57.Pannu HK, Scatarige JC, Eng J. Comparison of
supine magnetic resonance imaging with and
without rectal contrast to fluoroscopic cystocolpoproctography for the diagnosis of pelvic organ prolapse. J Comput Assist Tomogr 2009; 33:125–130
58.Hecht EM, Lee VS, Tanpitukpongse TP, et al.
MRI of pelvic floor dysfunction: dynamic true
fast imaging with steady-state precession versus
HASTE. AJR 2008; 191:352–358
59.Etlik Ö, Arslan H, Odabaşi H, et al. The role of
the MR-fluoroscopy in the diagnosis and staging
of the pelvic organ prolapse. Eur J Radiol 2005;
53:136–141
60.Cortes E, Reid WMN, Singh K, Berger L. Clinical examination and dynamic magnetic resonance
imaging in vaginal vault prolapse. Obstet Gynecol
2004; 103:41–46
61.Singh K, Reid WMN, Berger LA. Assessment and
grading of pelvic organ prolapse by use of dynamic magnetic resonance imaging. Am J Obstet Gy-
necol 2001; 185:71–77
62.Woodfield CA, Hampton BS, Sung V, Brody JM.
Magnetic resonance imaging of pelvic organ prolapse: comparing pubococcygeal and midpubic
lines with clinical staging. Int Urogynecol J Pelvic Floor Dysfunction 2009; 20:695–701
63.Lienemann A, Sprenger D, Janßen U, Grosch E,
Pellengahr C, Anthuber C. Assessment of pelvic
organ descent by use of functional cine-MRI:
which reference line should be used? Neurourol
Urodyn 2004; 23:33–37
64.Hodroff MA, Stolpen AH, Denson MA, Bolinger
L, Kreder KJ. Dynamic magnetic resonance imaging of the female pelvis: the relationship with
the pelvic organ prolapse quantification staging
system. J Urol 2002; 167:1353–1355
65.Comiter CV, Vasavada SP, Barbaric ZI, Gousse
AE, Raz S. Grading pelvic prolapse and pelvic
floor relaxation using dynamic magnetic resonance imaging. Urology 1999; 54:454–457
66.Dvorkin LS, Hetzer F, Scott SM, Williams NS, Gedroye W, Lunniss PJ. Open-magnet MR defecography compared with evacuation proctography in the
diagnosis and management of patients with rectal
intussusception. Colorectal Dis 2004; 6:45–53
67.Mortele KJ, Fairhurst J. Dynamic MR defecography of the posterior compartment: indications,
techniques and MRI features. Eur J Radiol 2007;
61:462–472
68.Boyadzhyan L, Raman SS, Raz S. Role of static
and dynamic MR imaging in surgical pelvic floor
dysfunction. RadioGraphics 2008; 28:949–967
69.Healy JC, Halligan S, Reznek RH, et al. Magnetic
resonance imaging of the pelvic floor in patients
with obstructed defaecation. Br J Surg 1997;
84:1555–1558
70.Fielding JR, Dumanli H, Schreyer AG, et al. MRbased three-dimensional modeling of the normal
pelvic floor in women: quantification of muscle
mass. AJR 2000; 174:657–660
71.Terra MP, Beets-Tan RG, van Der Hulst VP, et al.
Anal sphincter defects in patients with fecal incontinence: endoanal versus external phased-array MR imaging. Radiology 2005; 236:886–895
72.Rociu E, Stoker J, Eijkemans MJC, Schouten WR,
Laméris JS. Fecal incontinence: endoanal sonography versus endoanal MR imaging. Radiology
1999; 212:453–458
73.Briel JW, Zimmermann DD, Stoker J, et al. Relationship between sphincter morphology on endoanal MRI and histopathological aspects of the external anal sphincter. Int J Colorectal Dis 2000;
15:87–90
74.Bump RC, Mattiasson A, Bø K, et al. The standardization of terminology of female pelvic organ
prolapse and pelvic floor dysfunction. Am J Obstet
Gynecol 1996; 175:10–17
F O R YO U R I N F O R M AT I O N
This article is available for CME credit. See www.arrs.org for more information.
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