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Chapter 10
Chapter 10 Imaging of the Pelvic Floor
Imaging of the Pelvic Floor –
Videoproctography and Dynamic MRI
of the Pelvic Floor
Alois Fürst,Lilli Hutzel, Klaus Guenther, Andreas Schreyer,
Christian Paetzel
137
10
Contents
10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 138
10.2 Technical Necessities to Perform Defecography . . . . . . 138
10.3 Radiation Dose of Defecography . . . . . . . . . . . . . . 139
10.4 Standards of Evaluation . . . . . . . . . . . . . . . . . . . 139
10.5 Information from a Correctly Performed Defecography . 140
10.6 Technical Necessities to Perform a Dynamic MRI
of the Pelvic Floor . . . . . . . . . . . . . . . . . . . . . . 142
10.7 How to Perform Dynamic MRI . . . . . . . . . . . . . . . 142
10.8 Indication for Dynamic MRI . . . . . . . . . . . . . . . . . 143
10.9 Costs of Conventional Defecography and Dynamic MRI . 143
10.10 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
10.11 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 152
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
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Alois Fürst, Lilli Hutzel, Klaus Guenther, Andreas Schreyer, Christian Paetzel
10.1 Introduction
Pelvic floor disorders are manifold. Outlet obstruction, anismus, inertia recti, descending perineum syndrome, dyskinesia of the puborectal muscle, intussusception,
prolapse of the anus and rectum, vaginal prolapse, rectocele, cystocele and enterocele
are common diagnoses in proctology. Besides constipation, problems with incontinence for stool or urine are the most common symptoms.Women are affected at a significantly higher rate (ratio 9:1) (Winkler and Otto 1997). Patients usually seek help
from gynecologists, urologists, dermatologists and proctologists. Therefore,diagnostic and therapeutic strategies for an interdisciplinary approach are needed.
A thorough medical history and proctologic examination (inspection, palpation,
rectoscopy, proctoscopy) along with manometry and endosonography are the basic
diagnostic tools in complex pelvic floor disorders, and evacuation proctography may
yield additional information (Herold et al. 1999).
With the improvement of magnetic resonance imaging (MRI) technology, dynamic
MRI of the pelvic floor has become an alternative option in the diagnostic process of
combined pelvic floor disorders.Since its introduction by Yang et al. (1991) and Kruyt
et al. (1991) in 1991, MRI is increasingly replacing evacuation proctography first described in 1952 by L.Walldén (1952) for the evaluation of outlet obstruction.
In the evaluation of enteroceles and uterovaginal prolapses, MRI of the pelvic floor
seems to be favorable in some aspects compared to clinical examination and evacuation proctography (Yang et al. 1991; Kruyt et al. 1991; Goodrich et al. 1993; Healy et al.
1997a,b; Lienemann et al.1997, 2000). In addition, examination series in MRI can be repeated without any ionizing radiation. This may increase the chances of detecting
pathological findings in some patients (Lienemann et al.1997).
On the other hand, the horizontal position of the patient during MRI may influence
pelvic floor physiology. Therefore, some authors consider videoproctography to have
advantages over MRI in the diagnosis of enteroceles or rectoceles (Delemarre et al.
1994; Vanbeckevoort et al. 1999).
So far,patient preparation, examination technique and reference lines for the evaluation of MRI have not been standardized and findings differ widely in the published
studies. Most of the studies did not examine the defecation process. Normal findings
and normal values were defined in small control groups and therefore were only applicable in the actual study setting. For these reasons, MRI cannot yet replace videoproctography in the evaluation of pelvic floor disorders.
10.2 Technical Necessities to Perform Defecography
Videoproctography is performed as usual in lateral projection with patients in the upright position sitting on a specially designed commode. The rectum is filled with
150–200 ml of a barium paste. The visualization of a cystocele or a vaginal prolapse requires filling the bladder with contrast medium and inserting a vaginal tampon, respectively. To visualize an enterocele, the oral administration of contrast medium is
necessary. Patients first are asked to relax the pelvic floor and then to empty the rectum as completely as possible. Images are obtained at a frequency of one per second
during defecation.
Chapter 10 Imaging of the Pelvic Floor
10.3 Radiation Dose of Defecography
Radiation exposure of the patient during defecography is an important point. Most
patients referred to the radiologist for defecography are women and some are still of
childbearing age. Therefore, the possibility of potential genetic damage is an important issue. Since defecography is a dynamic investigation, a series of images is necessary.There are three options to perform a conventional defecography:
쐽 Use of 100-mm image intensifier photography with frequent single shots
or with the serial technique. Ovarian dose measurements of 15±5 mSv were
published by Goei and Kemerink in 1990.
쐽 Video recording has the disadvantage of a poorer image quality. Brühlmann
and Müller-Duysing measured doses of 9 mSv for the ovary proximal to the
X-ray tube.Ovarian doses of 4–16 mSv were published from other investigators.
쐽 Cineradiography combines image quality with good temporal resolution.
However, ovarian doses of 60 mSv were measured, which are unacceptably
high doses to women of childbearing age.
New digital imaging techniques can reduce the dose resulting in an approximately
twofold lower dose–area product (Broadhead et al. 1995). Additionally low-dose digital programs with added copper filtration have the lowest dose showing still adequate
image quality (Hare et al. 2001).
139
10.4 Standards of Evaluation
The reference line was the pubococcygeal line (Fig. 10.1),movement of pelvic floor organs was measured as the vertical distance to this line. Above the pubococcygeal line
values were marked positive (+), values below this line were marked negative (–).
Fig. 10.1.
Diagram of the pubococcygeal line (black) joining the
most inferior part of the pubic symphysis and the last
coccygeal joint.Additionally
this figure shows the bladder
base, uterocervical junction
and the anorectal junction
(gray dots from left to right)
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Alois Fürst, Lilli Hutzel, Klaus Guenther, Andreas Schreyer, Christian Paetzel
Data were recorded in resting position as well as during the defecation process with
maximal straining. All data (except those typified) are mean values with corresponding standard deviations.
The anorectal junction was defined as the intersection point of the central axis of
the anal canal and a line along the posterior rectal wall. The anorectal angle was measured between these two lines (Yang et al. 1991; Healy et al.1997a; Lienemann et al. 1997).
According to the literature, based on different evaluation techniques,a rectocele is
defined as a bulge of the anterior rectal wall of approximately 20–30 mm (Delemarre
et al. 1994).For data analysis of the videoproctography and MRI,we applied the method described by Delemarre et al. (1994), who defined a rectocele as the distance from
the anorectal junction to the tip of the protrusion of the anterior rectal wall.
Due to the imaging technique, only MRI revealed data on the position of the bladder base, the uterocervical junction and the vagina. Also,an enterocele could only be
assessed by MRI.
A cystocele and a uterovaginal prolapse were diagnosed if the bladder base or the
uterocervical junction fell below the pubococcygeal line during defecation (Lienemann et al. 1997, 2000).Widening of the rectovaginal space or a descent of mesenteric
parts, small bowel or sigmoid colon beyond the pubococcygeal line during defecation
was defined as an enterocele (Healy et al. 1997b; Lienemann et al. 2000).
During the stages of defecation, the following parameters should be considered:
쐽 The anorectal angle: the angle between the axis of the anal canal and the line
along the posterior border of the distal rectal wall
쐽 The position of the anorectal junction in relation to the pubococcygeal line
쐽 The movement of the anorectal junction from rest to squeezing and from rest
to straining
쐽 The amount of rectal emptying
쐽 The morphological changes of the rectal wall
10.5 Information from a Correctly Performed Defecography
The main application of defecography is for the detection of anatomical abnormalities
as the possible cause of defecation disorders. The following findings of defecography
are common:
쐽 Intussusception (Fig.10.2)
쐽 Rectocele (Fig.10.3)
쐽 Prolapse
쐽 Descending perineum syndrome
쐽 Solitary rectal ulcer
쐽 Spastic pelvic floor syndrome
쐽 Evacuation disorders
Fig. 10.2.
Intussusception of the rectal wall at
the end of defecation
Fig. 10.3.
Rectocele shown by a conventional
videoproctography
Chapter 10 Imaging of the Pelvic Floor
141
There is a wide interobserver variation in the measurements of defecography and also
a wide variation among healthy individuals. In addition,a great proportion of healthy
people show abnormalities at defecography with no clinical symptoms. Therefore,the
results of a defecography should be interpreted very carefully must be consistent with
the clinical findings.
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Alois Fürst, Lilli Hutzel, Klaus Guenther, Andreas Schreyer, Christian Paetzel
10.6 Technical Necessities to Perform a Dynamic MRI
of the Pelvic Floor
Dynamic imaging requires scanners that allow the acquisition of sequences with a
frame rate of approximately 1/s.Normally the modern generation of MR scanners with
a field strength of 1–1.5 T and an slew rate of 50 T/m/s and more fulfill this condition.
T2-weighted gradient echo sequences called RARE, Haste or True Fisp are utilized
(Gufler et al.1999; Paetzel et al. 2001).Dynamic images are acquired in a median sagittal plane, for example with a True Fisp single-slice sequence with a slice thickness of
5–6 mm (TR, 5.8 ms; TE,2.5 ms; flip angle, 70°; matrix,256×256; field of view,270 mm;
total measurements of approximately 30–50 s;in-plane resolution, 1.02 mm) (Gufler et
al. 1999; Paetzel et al. 2001).
10.7 How to Perform Dynamic MRI
Patient preparation plays an important role in the comparison of both procedures.Patients were asked to urinate 3 h before examination to achieve a medium filling of the
urinary bladder during MRI. The rectum was filled with 180 ml of a gadolinium-based
ultrasound gel mixture (Gd-DTPA-GEL-Mixture, 1%).MRI (1.5-T, Magnetom Symphony, Siemens, Erlangen, Germany) was performed in a supine position with hips and
knees bent at 45°. The pelvic floor was visualized in three planes (transversal, coronary,sagittal, T1 and T2) to find the appropriate sagittal plane in which pelvic floor organs during defecation were recorded over 50 s at a frequency of one shot per 0.8 seconds (true FISP). Scan progression was 6 mm (format, 270×270 mm). During the ex-
Fig. 10.4. Descending perineum including a cystocele, uterovaginal descensus and rectocele
shown by dynamic MRI
Chapter 10 Imaging of the Pelvic Floor
amination,patients were instructed via headphones. They first were asked to relax and
then to perform repeated straining maneuvers to empty the rectum as completely as
possible. The sequences were recorded digitally and analyzed cinematographically
(Gufler et al. 1999; Paetzel et al. 2001).
Evaluation was also simplified without missing diagnostic tools. The lower pubococcygeal line was used in both procedures to visualize relative movements of the pelvic organs during defecation (Fig. 10.4).The anorectal junction and the anorectal angle were determined by the central axis of the anal canal and a line along the posterior wall of the rectum (Healy et al. 1997b; Lienemann et al.1997, 2000).According to Delemarre et al. (1994), rectoceles were measured from the anorectal junction to the tip
of protrusion of the anterior rectum wall (Table 10.1).
10.8 Indication for Dynamic MRI
Combined and complex pelvic floor disorders may indicate dynamic pelvic MRI. A
host of combined diagnoses and symptoms such as descending perineum syndrome,
rectocele, cystocele, enterocele, uterine and vaginal descensus, anal and rectal prolapse, outlet obstruction, anismus, inertia recti and intussusception can be visualized
with one diagnostic procedure.
Besides descent of the perineum and constipation, problems with incontinence for
stool or urine are the most common symptoms.Women are affected at a significantly
higher rate (ratio, 9: 1; Winkler and Otto 1997). Patients usually seek help from gynecologists, urologists, gastroenterologists and proctologists. Therefore, a visualizing
procedure which includes all anatomical structures of the pelvis is attractive.
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Indications for dynamic MRI of the pelvis:
쐽 Descending perineum syndrome
쐽 Rectocele
쐽 Cystocele
쐽 Enterocele
쐽 Uterine and vaginal descensus
쐽 Anal and rectal prolapse
쐽 Outlet obstruction
쐽 Anismus
쐽 Inertia recti
쐽 Intussusception
10.9 Costs of Conventional Defecography and Dynamic MRI
It seems to be difficult to assess the real cost of a pelvic MRI in patients during their
stay at the hospital.The material used for an examination (Gd-DTPA 2 ml, ultrasound
gel) are not worth mentioning. The MRI scanner time of approximately 20 min is comparable to the conventional fluoroscopically performed examination.It is still difficult
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Alois Fürst, Lilli Hutzel, Klaus Guenther, Andreas Schreyer, Christian Paetzel
10
Yang et al. Kruyt et al. Vanbeckevoort Lienemann Healy et al. Hutzel et al.
(1991) (1991) et al. (1999) et al. (1997) (1997a) (2002a)
DefecationNoNoNoNoNoYes
Rectal contrast No No 100 ml ug 200 ml ug Plastic tube 180 ml ug
Bladder contrast No No No 60 ml NaCl No No
Vaginal contrast No No No 50 ml ug Plastic tube No
Position Horizontal Prone Horizontal Horizontal Horizontal Horizontal
Table 10.1. Patient preparation,evaluation techniques,normal values and findings as described by other authors
Reference line Pubococcygeal Symphysiosacral Pubosacral Pubococcygeal Pubococcygeal Pubococcygeal
Bladder base –10 mm No information ±0 ±0 –10 mm Discussed
Anorectal junction –25 mm –30 to –40 mm –25 No information –20 mm Discussed
Uterocervical junction +10 mm No information No information +0 ±0 Discussed
Rectocele (evaluation) No information No information Yoshioka Yoshioka Yoshioka Delemarre
Rectocele (size) No information No information <30 mm <30 mm No information Discussed
Anorectal angle No information <130° (rest) No information No information No information Discussed
Enterocele No information No information w. RVS w. RVS w.RVS w.RVS
ug, customary ultrasound gel; Gd 1%,mixture with gadolinium 1%; NaCl, isotonic saline solution; w. RVS, widened rectovaginal space.
Measurement of rectoceles according to Yoshioka (Gufler et al. 1999) : from the assumed anterior wall of the anal canal to the maximal anterior protrusion of the
Data for anorectal junction, bladder base and uterocervical junction: normal values were defined as positions cranial to the individual reference lines.
rectocele; according to Delemarre et al.(1994): from the anorectal junction to the maximal anterior protrusion of the rectocele.
Size of the rectocele and anorectal angle: normal findings had to be below the given values
Chapter 10 Imaging of the Pelvic Floor
to assess the occupation of different modalities correctly. The presence of a physician
seems to be slightly shorter in MR imaging. On an outpatient basis,a conventional defecography is covered with 58.29 euros, a dynamic pelvic MRI with 303.09 euros (in
Germany: GOÄ – E 3003.09).
10.10 Discussion
Dynamic MRI of the pelvic floor is increasingly used in the diagnosis of complex pelvic floor disorders and is replacing videoproctography more and more. Different specialties (radiology,urology, gynecology and surgery) are engaged with the interpretation and comparability of findings and with the definition of normal values and reasonable reference lines.
Since there is a lack of standardized comparative studies, special emphasis was laid
on simplification and standardization of the examination technique. In 1991,Kruyt et
al. was one of the first who used magnetic resonance to study functional aspects of the
anorectal region.Also in 1991, Yang et al. introduced the dynamic MRI as a new method in the diagnosis of descending perineum in women. Values were recorded under
various degrees of straining maneuvers. Defecation itself was not studied since the
rectum was not filled with a contrast medium.As in the present study, the lower pubococcygeal line was taken as reference line to evaluate the descent of the pelvic organs.
Another study comparing clinical examination, videoproctography and dynamic
MRI in the diagnosis of anterior rectoceles was published by Delemarre et al. (1994).
In this study patients were examined in the prone position without rectal filling, which
made evaluation of the defecation process impossible. The pubosacral line reaching
from the most inferior part of the pubic symphysis to the lower part of the sacrum was
chosen as the reference line in MRI.Measurements were performed at rest and during
straining for both imaging techniques. Healy et al. (Healy et al. 1997b; Hilfiker et al.
1998) analyzed various aspects of pelvic floor disorders in patients and healthy volunteers,comparing videoproctography and dynamic MRI. For MRI, patients were placed
in the supine position; defecation was not recorded. In contrast to other studies
(Lienemann et al.1997, 2000;Vanbeckevoort et al. 1999),instead of a contrast medium,
a tampon was placed in the rectum to mark the rectal lumen.Measurements were performed during maximal straining; the reference line was the lower pubococcygeal
line.
Tacke et al. (Bertschinger et al. 2002) tested a new method of dynamic MRI with radial real-time imaging and a reduced image area for defecography. Patients were asked
to void a condom filled with a gadolinium-based contrast gel in the supine position.
The authors themselves discussed this form of rectal filling critically, as it may mask
an intussusception or a latent incontinence.
Vanbeckevoort et al. (1999) compared colpocystoproctography (videoproctography with opacification of vagina and bladder) and dynamic MRI in the supine position. For MRI, the rectum was filled with 100 ml of ultrasound gel that was not meant
to be voided. Measurements were taken during maximal straining, the reference line
was a line from the most inferior part of the pubic symphysis to the lower part of the
sacrum, which was also called pubococcygeal line (corresponding to the pubosacral
line according to Delemarre et al.1994).
Lienemann et al. (2000) compared colpocystoproctography and MRI in the diagnostic of enteroceles. In MRI, patients and healthy volunteers were placed in a supine
position and the rectum was filled with 200 ml of ultrasound gel which was to be def-
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Alois Fürst, Lilli Hutzel, Klaus Guenther, Andreas Schreyer, Christian Paetzel
ecated during the imaging. The study does not reveal data on frequency and completeness of the defecation process.Reference line was the lower pubococcygeal line.
In a technically equal approach, Lienemann et al. (1997) examined 44 female patients and five asymptomatic volunteers for descent of the pelvic floor. Also in this
study patients and volunteers were asked not to void the gel. There was no discussion
of the findings of the healthy volunteers in this study.
Schoenberger et al. (1998) and Hilfiker et al. (1998;Bertschinger et al.2002) presented an open-system MRI where patients were examined in an upright position analogous to videoproctography. In the study of Schoenberger et al.(1998) the findings of 15
patients examined with videoproctography and this new form of open configured
MRI were compared. Five healthy volunteers were included for the definition of normal values,which are not mentioned in the paper so that comparison with other studies is not possible.
This overview illustrates the problems of introducing a new examination technique. So far, dynamic MRI is widely accepted as a promising technique in the diagnosis of the pelvic floor (Yang et al. 1991;Kruyt et al. 1991; Goodrich et al. 1993; Lienemann
et al. 1997, 2000), particularly for functional aspects of pelvic floor disorders, since pelvic organs and muscles can be visualized and evaluated without invasive opacification
or exposure to radiation. Still, without standardization of patient preparation, examination technique and evaluation of the data according to standardized reference lines
and landmarks, it may not yet replace a well-established technique like videoproctography (or colpocystoproctography). We believe that a comparison of both procedures
has to take place under standardized conditions. In this context,the documentation of
the defecation process is most important for subsequent comparability of both techniques.Vanbeckevoort et al.(1999) compared the results of 35 patients examined with
colpocystoproctography with and without defecation with the findings of dynamic
MRI without defecation. For colpocystoproctography, the urinary bladder and the
small bowel were filled with a contrast medium. In their analysis, colpocystoproctography including defecation was by far superior to the same technique without defecation. Based on the observation that the pelvic floor reached its maximal downward
movement only during defecation and supported by the fact that patients are placed in
a horizontal position in MRI, the authors concluded that colpocystoproctography including defecation may also be superior to MRI without defecation. In our opinion,
this is a further argument for the examination of the defecation process in MRI. Our
own findings also showed that in patients and healthy volunteers the formation of a
rectocele, enterocele and cystocele as well as the maximal descent of the anorectal
junction and of the uterocervical junction was only completely visible towards the end
of the defecation process but not during straining alone.
Besides the descent of the anorectal junction (Fig. 10.5), changes in the anorectal
angle (Fig. 10.6) are commonly used as an indicator for the functional status of the pelvic floor.A narrowing of the anorectal angle may indicate a disorder of the puborectal
muscle.This may lead to constipation with subsequent straining leading to a rectal intussusception,rectocele and a mucosal prolapse with a solitary ulcer of the rectum, as
postulated by several authors.If the anorectal angle is already widened at rest, this may
be a sign of weakness of the pelvic floor and is commonly observed along with incontinence and a rectal prolapse. Normal values in the literature vary enormously. For
videoproctography normal values were indicated between 60° and 105° at rest, whereas the findings of other groups relying on control groups with up to 150 volunteers
show values between 90° and 104° at rest and 103° to 137° during defecation.Accordingly, the use of changes in the anorectal angle as a diagnostic parameter is difficult not
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