MR imaging of the female pelvic floor in the supine and upright positions

Development of Upright Computed Tomography With Area Detector for Whole-Body Scans: Phantom Study, Efficacy on Workflow, Effect of Gravity on Human Body, and Potential Clinical Impact

OBJECTIVES

Multiple human systems are greatly affected by gravity, and many disease symptoms are altered by posture. However, the overall anatomical structure and pathophysiology of the human body while standing has not been thoroughly analyzed due to the limitations of various upright imaging modalities, such as low spatial resolution, low contrast resolution, limited scan range, or long examination time. Recently, we developed an upright computed tomography (CT), which enables whole-torso cross-sectional scanning with 3-dimensional acquisition within 15 seconds. The purpose of this study was to evaluate the performance, workflow efficacy, effects of gravity on a large circulation system and the pelvic floor, and potential clinical impact of upright CT.

MATERIALS AND METHODS

We compared noise characteristics, spatial resolution, and CT numbers in a phantom between supine and upright CT. Thirty-two asymptomatic volunteers (48.4 ± 11.5 years) prospectively underwent both CT examinations with the same scanning protocols on the same day. We conducted a questionnaire survey among these volunteers who underwent the upright CT examination to determine their opinions regarding the stability of using the pole throughout the acquisition (closed question), as well as safety and comfortability throughout each examination (both used 5-point scales). The total access time (sum of entry time and exit time) and gravity effects on a large circulation system and the pelvic floor were evaluated using the Wilcoxon signed-rank test and the Mann-Whitney U test. For a large circulation system, the areas of the vena cava and aorta were evaluated at 3 points (superior vena cava or ascending aorta, at the level of the diaphragm, and inferior vena cava or abdominal aorta). For the pelvic floor, distances were evaluated from the bladder neck to the pubococcygeal line and the anorectal junction to the pubococcygeal line. We also examined the usefulness of the upright CT in patients with functional diseases of spondylolisthesis, pelvic floor prolapse, and inguinal hernia.

RESULTS

Noise characteristics, spatial resolution, and CT numbers on upright CT were comparable to those of supine CT. In the volunteer study, all volunteers answered yes regarding the stability of using the pole, and most reported feeling safe (average rating of 4.2) and comfortable (average rating of 3.8) throughout the upright CT examination. The total access time for the upright CT was significantly reduced by 56% in comparison with that of supine CT (upright: 41 ± 9 seconds vs supine: 91 ± 15 seconds, P < 0.001). In the upright position, the area of superior vena cava was 80% smaller than that of the supine position (upright: 39.9 ± 17.4 mm vs supine: 195.4 ± 52.2 mm, P < 0.001), the area at the level of the diaphragm was similar (upright: 428.3 ± 87.9 mm vs supine: 426.1 ± 82.0 mm, P = 0.866), and the area of inferior vena cava was 37% larger (upright: 346.6 ± 96.9 mm vs supine: 252.5 ± 93.1 mm, P < 0.001), whereas the areas of aortas did not significantly differ among the 3 levels. The bladder neck and anorectal junction significantly descended (9.4 ± 6.0 mm and 8.0 ± 5.6 mm, respectively, both P < 0.001) in the standing position, relative to their levels in the supine position. This tendency of the bladder neck to descend was more prominent in women than in men (12.2 ± 5.2 mm in women vs 6.7 ± 5.6 mm in men, P = 0.006). In 3 patients, upright CT revealed lumbar foraminal stenosis, bladder prolapse, and inguinal hernia; moreover, it clarified the grade or clinical significance of the disease in a manner that was not apparent on conventional CT.

CONCLUSIONS

Upright CT was comparable to supine CT in physical characteristics, and it significantly reduced the access time for examination. Upright CT was useful in clarifying the effect of gravity on the human body: gravity differentially affected the volume and shape of the vena cava, depending on body position. The pelvic floor descended significantly in the standing position, compared with its location in the supine position, and the descent of the bladder neck was more prominent in women than in men. Upright CT could potentially aid in objective diagnosis and determination of the grade or clinical significance of common functional diseases.

Recommended standardized terminology of the anterior female pelvis based on a structured medical literature review

BACKGROUND

The use of imprecise and inaccurate terms leads to confusion amongst anatomists and medical professionals.

OBJECTIVE

We sought to create recommended standardized terminology to describe anatomic structures of the anterior female pelvis based on a structured review of published literature and selected text books.

STUDY DESIGN

We searched MEDLINE from its inception until May 2, 2016, using 11 medical subject heading terms to identify studies reporting on anterior female pelvic anatomy; any study type published in English was accepted. Nine textbooks were also included. We screened 12,264 abstracts, identifying 200 eligible studies along with 13 textbook chapters from which we extracted all pertinent anatomic terms.

RESULTS

In all, 67 unique structures in the anterior female pelvis were identified. A total of 59 of these have been previously recognized with accepted terms in Terminologia Anatomica, the international standard on anatomical terminology. We also identified and propose the adoption of 4 anatomic regional terms (lateral vaginal wall, pelvic sidewall, pelvic bones, and anterior compartment), and 2 structural terms not included in Terminologia Anatomica (vaginal sulcus and levator hiatus). In addition, we identified 2 controversial terms (pubourethral ligament and Grafenberg spot) that require additional research and consensus from the greater medical and scientific community prior to adoption or rejection of these terms.

CONCLUSION

We propose standardized terminology that should be used when discussing anatomic structures in the anterior female pelvis to help improve communication among researchers, clinicians, and surgeons.

Advances in basic science methodologies for clinical diagnosis in female stress urinary incontinence

We provide an overview of advanced imaging techniques currently being explored to gain greater understanding of the complexity of stress urinary incontinence (SUI) through better definition of structural anatomic data. Two methods of imaging and analysis are detailed for SUI with or without prolapse: 1) open magnetic resonance imaging (MRI) with or without the use of reference lines; and 2) 3D reconstruction of the pelvis using MRI. An additional innovative method of assessment includes the use of near infrared spectroscopy (NIRS), which uses non-invasive photonics in a vaginal speculum to objectively evaluate pelvic floor muscle (PFM) function as it relates to SUI pathology. Advantages and disadvantages of these techniques are described. The recent innovation of open-configuration magnetic resonance imaging (MRO) allows images to be captured in sitting and standing positions, which better simulates states that correlate with urinary leakage and can be further enhanced with 3D reconstruction. By detecting direct changes in oxygenated muscle tissue, the NIRS vaginal speculum is able to provide insight into how the oxidative capacity of the PFM influences SUI. The small number of units able to provide patient evaluation using these techniques and their cost and relative complexity are major considerations, but if such imaging can optimize diagnosis, treatment allocation, and selection for surgery enhanced imaging techniques may prove to be a worthwhile and cost-effective strategy for assessing and treating SUI.

Magnetic resonance imaging of pelvic floor dysfunction - joint recommendations of the ESUR and ESGAR Pelvic Floor Working Group

OBJECTIVE

To develop recommendations that can be used as guidance for standardized approach regarding indications, patient preparation, sequences acquisition, interpretation and reporting of magnetic resonance imaging (MRI) for diagnosis and grading of pelvic floor dysfunction (PFD).

METHODS

The technique included critical literature between 1993 and 2013 and expert consensus about MRI protocols by the pelvic floor-imaging working group of the European Society of Urogenital Radiology (ESUR) and the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) from one Egyptian and seven European institutions. Data collection and analysis were achieved in 5 consecutive steps. Eighty-two items were scored to be eligible for further analysis and scaling. Agreement of at least 80 % was defined as consensus finding.

RESULTS

Consensus was reached for 88 % of 82 items. Recommended reporting template should include two main sections for measurements and grading. The pubococcygeal line (PCL) is recommended as the reference line to measure pelvic organ prolapse. The recommended grading scheme is the "Rule of three" for Pelvic Organ Prolapse (POP), while a rectocele and ARJ descent each has its specific grading system.

CONCLUSION

This literature review and expert consensus recommendations can be used as guidance for MR imaging and reporting of PFD.

KEY POINTS

• These recommendations highlight the most important prerequisites to obtain a diagnostic PFD-MRI. • Static, dynamic and evacuation sequences should be generally performed for PFD evaluation. • The recommendations were constructed through consensus among 13 radiologists from 8 institutions.

Traction force needed to reproduce physiologically observed uterine movement: technique development, feasibility assessment, and preliminary findings

INTRODUCTION AND HYPOTHESIS

This study aimed to describe a novel strategy to determine the traction forces needed to reproduce physiologic uterine displacement in women with and without prolapse.

METHODS

Participants underwent dynamic stress magnetic resonance imaging (MRI) testing as part of a study examining apical uterine support. Physiologic uterine displacement was determined by analyzing uterine location in images taken at rest and at maximal Valsalva. Force-displacement curves were calculated based on intraoperative cervical traction testing. The intraoperative force required to achieve the uterine displacement measured during MRI was then estimated from these curves. Women were categorized into three groups based on pelvic organ support: group 1 (normal apical and vaginal support), group 2 (normal apical support but vaginal prolapse present), and group 3 (apical prolapse).

RESULTS

Data from 19 women were analyzed: five in group 1, five in group 2, and nine in group 3. Groups were similar in terms of age, body mass index (BMI), and parity. Median operating room (OR) force required for uterine displacement measured during MRI was 0.8 N [interquartile range (IQR) 0.62-3.22], and apical ligament stiffness determined using MRI uterine displacement was 0.04 N/mm (IQR 0.02-0.08); differences between groups were nonsignificant. Uterine locations determined at rest and during maximal traction were lower in the OR compared with MRI in all groups.

CONCLUSIONS

Using this investigative strategy, we determined that only 0.8 N of traction force in the OR was required to achieve maximal physiologic uterine displacement seen during dynamic (maximal Valsalva) MRI testing, regardless of the presence or absence of prolapse.

A protocol for dynamic magnetic resonance imaging of the pelvic floor

Methods of dynamic magnetic resonance imaging (dMRI) of the pelvic floor vary among centers making interpretation investigator-dependent and comparison of results difficult. We describe a protocol utilizing standard MRI equipment, which achieves high image quality while remaining practical and cost-effective. Fifteen patients, with difficulty in evacuation of stool, underwent dMRI. Each patient was trained prior to the procedure. The pelvis was mapped in the sagittal plane using T2-weighted dMRI in rest, strain and evacuation phases with rectal hydro-gel as contrast. Images obtained were used to identify and quantify the dynamics of each pelvic compartment. Acquisition time for each phase was 14 seconds. Extensive patient instruction and T2-weighted dMRI with rectal contrast optimized image quality and efficiency. The evacuation phase yielded data on the extent of dysfunction and compartment prolapse, not seen in the other phases. These findings led to change in management in 67 % (n=10) of patients.

Role of static and dynamic MR imaging in surgical pelvic floor dysfunction

Pelvic floor dysfunction (PFD) is a hidden women's health epidemic in the United States, with over 10% of women having a lifetime risk for undergoing a surgical repair for this problem. Given the paucity of understanding of PFD pathophysiology and the high rate of recurrence and repeat surgery, imaging plays a major role in its clinical management, especially for the preoperative assessment of patients with multicompartment defects and failed surgical repairs. The recent development of fast magnetic resonance (MR) imaging sequences allows noninvasive, radiation-free, rapid, high-resolution evaluation of the entire pelvis in one examination. The H line, M line, organ prolapse (HMO) classification system, which is applied to dynamic MR images, allows consistent standardization and grading of various forms of PFD. In addition, the HMO system clearly defines and differentiates between the two main components of PFD: pelvic floor relaxation and pelvic organ prolapse. In addition to serving as an objective diagnostic tool in patients with surgical PFD, MR imaging has tremendous potential to be used as a research tool in trying to understand the pathophysiology of these complex disorders.

MRI-based registration of pelvic alignment affected by altered pelvic floor muscle characteristics

BACKGROUND

Pelvic floor muscles have potential to influence relative pelvic alignment. Side asymmetry in pelvic floor muscle tension is claimed to induce pelvic malalignment. However, its nature and amplitude are not clear. There is a need for non-invasive and reliable assessment method. An intervention experiment of unilateral pelvic floor muscle activation on healthy females was performed using image data for intra-subject comparison of normal and altered configuration of bony pelvis.

METHODS

Sequent magnetic resonance imaging of 14 females in supine position was performed with 1.5 T static body coil in coronal orientation. The intervention, surface functional electrostimulation, was applied to activate pelvic floor muscles on the right side. Spatial coordinates of 23 pelvic landmarks were localized in each subject and registered by specially designed magnetic resonance image data processing tool (MPT2006), where individual error calculation; data registration, analysis and 3D visualization were interfaced.

FINDINGS

The effect of intervention was large (Cohen's d=1.34). We found significant differences in quantity (P<0.01) and quality (P=0.02) of normal and induced pelvic displacements. After pelvic floor muscle activation on the right side, pelvic structures shifted most frequently to the right side in ventro-caudal direction. The right femoral head, the right innominate and the coccyx showed the largest displacements.

INTERPRETATION

The consequences arising from the capacity of pelvic floor muscles to displace pelvic bony structures are important to consider not only in management of malalignment syndrome but also in treatment of incontinence. The study has demonstrated benefits associated with processing of magnetic resonance image data within pelvic region with high localization and registration reliability.

Dynamic magnetic resonance imaging used in evaluation of female pelvic prolapse: experience from nine cases

Prolapse of pelvic organs in a female can be simple or complex. To make a definite diagnosis of pelvic prolapse preoperatively, dynamic magnetic resonance (MR) is an alternative to conventional fluoroscopic or sonographic examination, with the advantage of providing greater details, and thus helping the surgeon to have a good preoperative plan. Nine women suffering from pelvic prolapse with or without urinary stress incontinence underwent dynamic MR imaging examination (1.0T Magnex100/HP, Shimadzu, Kyoto, Japan) before surgery. All patients were examined in the supine position. A single-shot ultra-high speed scan (FE/8/3.02-20 degrees, 128, 100%-100% 1 NEX 1 slice 10 mm L1.0 second) was used to obtain midline sagittal images, with the patients at rest and during pelvic strain. MR images were then obtained every 4 seconds. Each examination was analyzed, based on specific measurements, to determine the presence and extent of prolapse of pelvic organs. The pubococcygeal, levator hiatus width and muscular pelvic floor relaxation lines, and the angle of the levator plate were identified. Based on these measurements, multicompartment involvement in the pelvic prolapse was confirmed in five patients (5/9). Four patients (4/9) had single compartment involvement. Seven patients underwent surgery. All patients reported significant improvement in their symptoms and signs after surgical intervention. Two patients had an almost complete recovery. MR demonstrated simple or complex organ descent in all pelvic compartments, and may become a standard preoperative examination for pelvic floor abnormalities. The MR images facilitated comprehensive planning by the surgeon; thus, they can increase the success rate and help to accurately predict the outcome of the surgical intervention. The surgeons also expressed high postsurgical satisfaction with the information provided by dynamic MR.

Quantification of abdominal and pelvic floor muscle synergies in response to voluntary pelvic floor muscle contractions

The relative levels of pelvic floor muscle (PFM) activation and pressure generated by maximum voluntary PFM contractions were investigated in healthy continent women. The normal sequence of abdominal and PFM activation was determined. Fifteen women performed single and repeated maximum voluntary PFM contractions in supine, sitting and standing. PFM electromyographic (EMG) signals and associated intra-vaginal pressure data were recorded simultaneously. Surface EMG data were recorded from rectus abdominus (RA), external obliques (EO), internal obliques (IO) and transversus abdominus (TA). Abdominal and PFM EMG and intra-vaginal pressure amplitudes generated during voluntary PFM contractions were not different among the positions. Muscle activation sequence differed by position. In supine, EO activation preceded all other muscles by 27 ms (p = 0.043). In sitting, all of the muscles were activated simultaneously. In standing, RA and EO were activated 11 and 17 ms, respectively, prior to the PFMs and TA and IO were activated 10 and 12 ms, respectively, after the PFMs (p<<0.001). The results suggest that women are able to perform equally strong PFM contractions in supine, sitting and standing, however the pattern of abdominal and PFM activation varies by position. These differences may be related to position-dependent urine leakage in women with stress incontinence.

Coccygeal movement: Assessment with dynamic MRI

PURPOSE

Chronic coccygodynia is a difficult problem diagnostically and therapeutically. Moreover, there is no deep knowledge especially in the field of imaging of chronic coccygodynia. In this study several possible measurements are proposed, which all are able to demonstrate coccygeal movement during defecation, in order to assess coccygeal mobility using dynamic MRI during maximum contraction and during straining-evacuation.

MATERIALS AND METHODS

A dynamic MRI study of the pelvic floor was performed in 112 patients. Five methods of measurement were assessed. Coccygeal movements were determined through the evaluation of three angles pair and two different distances measured during the phase of maximum contraction and during the phase of straining-evacuation. Results were compared according to age, sex, parity and experience of minor trauma. No patient included in the study had coccygodynia. Measurements taken by two radiologist were compared to determine interobserver agreement.

RESULTS

The maximum measurement values of the two distances are homogeneous, between 9 and 9.4mm. The maximum measurement values of the three angles showed a difference that is between 21 degrees and 38 degrees . Two of three angles showed a major measurement values in the funtional texts. In only one patient the coccyx was not mobile.

CONCLUSION

Our dynamic MRI study indicates that the coccyx is mobile during defecation and that it is possible to demonstrate coccygeal excursions by assessing the difference between its positions at maximum contraction and during straining-evacuation. The measurement methods used in this study for evaluating coccygeal movements resulted in variably sized observed differences, but all yielded statistically significant results in demonstrating coccygeal excursion. Among the five measurement methods, two resulted in the largest differences. Our data indicate no correlation between coccygeal movements and age, sex, parity, minor trauma and coccygodynia.

A contextual model of pelvic floor muscle defects in female stress urinary incontinence: a rationale for physiotherapy treatment

On the basis of the current literature, we describe a model of structural defects in stress urinary incontinence (SUI) and how physiotherapy for SUI can affect each component of the model with reference to the relevant anatomy and pathophysiology. This model of SUI involves four primary structural defects: (1) increased tonic stress on the pelvic fascia due to pelvic floor muscle (PFM) tears; (2) fascial tearing due to PFM denervation; (3) fascial weakness resulting from tears; and (4) inefficient PFM contraction due to altered motor control. These four components interact to collectively weaken urethral closure and allow urine leakage under conditions of increased intra-abdominal pressure. Physiotherapy can strengthen the PFM and may improve the efficiency and/or timing of PFM contractions to reduce or eliminate SUI. It is worthwhile for motivated women with SUI to try PFM exercise therapy as a first approach to treatment. Women need to be individually instructed to ensure that they correctly perform PFM contractions and that they can monitor their own performance. Long-term, high-intensity exercise, including home exercise, is necessary to achieve maximum effect. Under these conditions the improvement in urinary continence with PFM exercise can be complete and enduring.

Levator ani thickness variations in symptomatic and asymptomatic women using magnetic resonance-based 3-dimensional color mapping

OBJECTIVE

This study was undertaken to develop and test a 3-dimensional (3D) color thickness mapping technique on levator ani imaged with magnetic resonance imaging (MRI).

METHODS

Supine MRI datasets from 30 women were studied: 10 asymptomatic, 10 with urodynamic stress incontinence, and 10 with pelvic organ prolapse. Levators were manually outlined, and thickness mapping applied. Three-dimensional models were colored topographically, reflecting levator thickness. Thickness and occurrences of absent levator substance (gaps) were compared across the 3 groups, using nonparametric statistical tests.

RESULTS

Color thickness mapping was successful in all subjects. There were statistically significant differences in thickness and gap percentages among the 3 groups of women, with thicker, bulkier levators in asymptomatic women, compared with women with prolapse or urodynamic stress incontinence.

CONCLUSION

Color thickness mapping is feasible. It may be used to compare levators in symptomatic and asymptomatic women, to study relationships between levator thickness and pelvic floor dysfunction. This technique can be used in larger studies for hypothesis testing.

Incontinence and voiding difficulties associated with prolapse

PURPOSE

Prolapse is the protrusion of a pelvic organ beyond its normal anatomical confines. It represents the failure of fibromuscular supports.

MATERIALS AND METHODS

A MEDLINE search was done using the keywords cystocele, uterine prolapse, vault prolapse, enterocele or rectocele in combination with urinary incontinence. We reviewed 97 articles. From this material the definition, classification, incidence, symptoms and evaluation are described.

RESULTS

Prolapse and urinary incontinence often occur concomitantly and cystocele, rectocele, enterocele, uterine descent or vaginal vault prolapse may also be present. The pathophysiology of prolapse encompasses direct and indirect injury, metabolic abnormalities and chronic high intra-abdominal pressure. Anterior vaginal wall prolapse may present as stress incontinence. A large cystocele may cause urethral kinking and overflow incontinence. Uterine descent can cause lower back and sacral pain. Enterocele may cause only vague symptoms of vaginal discomfort. A rectocele can lead to incomplete evacuation of stool. A thorough history and physical examination are the most important means of assessment. A voiding diary helps determine functional bladder capacity. Uroflow examination determines the average and maximum flow rates, and the shape of the curve can help identify Valsalva augmented voiding. Multichannel urodynamics or video-urodynamics with prolapse reduced can be important. The advantages of dynamic magnetic resonance imaging include excellent depiction of the soft tissues and pelvic organs, and their fluid content during various degrees of pelvic strain. To our knowledge whether it is cost-effective in this manner has not been determined.

CONCLUSIONS

Correction of prolapse must aim to restore vaginal function and any concomitant urinary incontinence.

Clinical examination and dynamic magnetic resonance imaging in vaginal vault prolapse

OBJECTIVE

To estimate the role of dynamic magnetic resonance imaging (MRI) as a diagnostic tool in the evaluation of vaginal apex prolapse in women with previous hysterectomy.

METHODS

Clinical examinations were performed on 51 women presenting with symptoms of prolapse. A preoperative dynamic MRI assessment was performed. The mid pubic line was the reference level used for prolapse grading. The parameters of analysis included 1). correlation by compartments of clinical and MRI grading of prolapse, 2). assessment of the accuracy of clinical examination of the middle compartment, and 3). identification of any additional information provided by MRI. All MRI films were analyzed and validated by the same two observers.

RESULTS

Analysis of each compartment separately revealed poor correlation between clinical and MRI assessment. Of the 51 cases with clinical vault prolapse, 27 (52.9%) cases were clinically overdiagnosed, 3 (6%) were underdiagnosed, and there was agreement in 21 (41.1%) when compared with MRI findings. Postoperative follow-up of the 18 (85%) patients who underwent colposacropexy after intraoperative assessment revealed the presence of cystocele in 4 (26.6%) occasions and rectocele in 3 (20%), which had been detected on MRI but not confirmed intraoperatively.

CONCLUSION

There is poor correlation between clinical and MRI findings when assessing vaginal apex prolapse. Magnetic resonance imaging allows the identification of other prolapsing compartments and may be a complementary diagnostic tool for the diagnosis of complex vaginal apex prolapse.

The urethra and its supporting structures in women with stress urinary incontinence: MR imaging using an endovaginal coil

OBJECTIVE

The objective of this study was to evaluate the urethra and its supporting structures in patients with stress urinary incontinence using MR imaging with an endovaginal coil.

SUBJECTS AND METHODS

We reviewed MR images obtained using an endovaginal coil in 63 patients with stress urinary incontinence and in 16 continent women. We compared the two groups for the thickness of the striated muscle, smooth muscle, and mucosa-submucosa of the urethra; degree of asymmetry of the puborectalis muscle; frequency of distortion in the periurethral, paraurethral, and pubourethral ligaments; degree of the vesicourethral angle; and dimension of the retropubic space. Using the status of the urethra and its supporting structures as our basis, we scored the risk of stress urinary incontinence for each woman on a scale of 0-5.

RESULTS

The striated muscle layer of the urethra was thinner in the group with stress urinary incontinence (mean +/- SD, 1.9 +/- 0.5 mm) than that in the continent group (2.6 +/- 0.4 mm) (p < 0.001). A high degree of asymmetry of puborectalis muscle (>1.5) was more frequent in the group with stress urinary incontinence (29%) than in the continent group (0%) (p = 0.015). Supporting ligaments were more frequently distorted in the incontinent group than in the continent group. Distorted periurethral ligaments were found in 56% of the patients with stress urinary incontinence versus 13% of the women who were continent; distorted paraurethral ligaments were found in 83% of the patients with stress urinary incontinence versus 19% of the women who were continent; and distorted pubourethral ligaments were found in 54% of the patients with stress urinary incontinence versus 19% of the women who were continent (p < 0.05). The group with stress urinary incontinence had a greater vesicourethral angle (148 degrees vs 125 degrees ) and larger retropubic space (7.5 vs 5.1 mm) than did the women who were continent (p < 0.05). The score for the risk of stress urinary incontinence was higher in the group with stress urinary incontinence (3.3 +/- 1.4) than in the women who were continent (1.0 +/- 1.2) (p < 0.001).

CONCLUSION

MR imaging with an endovaginal coil revealed significant morphologic alterations of the urethra and supporting structures in patients with stress urinary incontinence.

Dynamic MR imaging of female organ prolapse

MR imaging is a viable technique for evaluating pelvic organ prolapse. Dynamic imaging with adequate increase in abdominal pressure is necessary for a successful study. Rectal contrast for patient defecation is easy to administer and also allows for the diagnosis of rectal abnormalities. Additional work is needed on the soft tissue changes of prolapse and grading criteria for MR.

Magnetic resonance imaging for stress incontinence: evaluation of patients before and after surgical correction

OBJECTIVE

The purpose of this study was to evaluate the accuracy of magnetic resonance imaging (MRI) in the pre and postoperative assessment of stress urinary incontinence.

METHODS

Fifteen female patients with clinical evidence of stress urinary incontinence were included in this prospective study. All the patients underwent MRI in the supine position both preoperatively and postoperatively. For imaging, we used a 1.0 T magnet, T2-weighted images were obtained in the midline sagittal plane with patients at rest. Images were evaluated for anatomical stress urinary incontinence alterations, such as the increased distance between the pubococcygeal line and the bladder base and the posterior urethro-vesical angle and the urethral inclination angle changes. Wilcoxon signed rank test allowed comparisons of pre and postoperative results.

RESULTS

Compared with postoperative measurements, the bladder base was lowered significantly by an average of 9.4+/-4.0 mm (P<0.01), posterior urethro-vesical angle was significantly increased by an average of 127.8+/-11.4 degrees (P<0.01), and the urethral inclination angle was significantly increased by an average of 54.9+/-10.1 degrees (P<0.01) preoperatively.

CONCLUSION

Our results suggest that MRI can play a major role in the preoperative and postoperative assessment of stress urinary incontinence. It can reliably detect anatomical urinary incontinence alterations. MRI should be considered in failed surgery, complex prolapse, and in differentiating genuine stress incontinence resulting from malposition of the bladder neck from stress incontinence due to intrinsic urethral damage.

Experience of 4 years with open MR defecography: pictorial review of anorectal anatomy and disease

Functional disorders of the pelvic floor are a common clinical problem. Diagnosis and treatment of these disorders, which frequently manifest with nonspecific symptoms such as constipation or incontinence, remain difficult. Fluoroscopic x-ray defecography has been shown to aid in detection of functional and morphologic abnormalities of the anorectal region. With the advent of open-configuration magnetic resonance (MR) imaging systems, MR defecography with the patient in a vertical position became possible. MR defecography permits analysis of the anorectal angle, the opening of the anal canal, the function of the puborectal muscle, and the descent of the pelvic floor during defecation. Good demonstration of the rectal wall permits visualization of intussusceptions and rectoceles. Excellent demonstration of the perirectal soft tissues allows assessment of spastic pelvic floor syndrome and descending perineum syndrome and visualization of enteroceles. MR defecography with an open-configuration magnet allows accurate assessment of anorectal morphology and function in relation to surrounding structures without exposing the patient to harmful ionizing radiation.

The clinical value of dynamic magnetic resonance imaging in normal and incontinent women--a preliminary study on micturition

In this preliminary study in nine volunteers and nine women with genuine stress incontinence (GSI) dynamic magnetic resonance imaging (MRI) was used to study the voiding phase in the sitting position after physiological filling of the bladder by urine. The MRI technique has been documented as being useful for this purpose, but in this small group of women it was not possible to determine any specific difference in the voiding pattern between the volunteers and the G

Practical MR imaging of female pelvic floor weakness

Pelvic floor weakness is common in middle-aged and elderly parous women and is often associated with stress incontinence, uterine prolapse, constipation, and incomplete defecation. Most patients with incontinence and minimal pelvic floor weakness can be treated based on physical examination and basic urodynamic findings. However, in women with symptoms of multicompartment involvement for whom a complex repair is planned or who have undergone previous repairs, magnetic resonance (MR) imaging can be a useful preoperative planning tool. The MR imaging evaluation is performed with the patient in the supine position, without contrast agents, and within 15 minutes. A multicoil array and a rapid half-Fourier T2-weighted imaging sequence are used to obtain sagittal images while the patient is at rest and during pelvic strain, followed by axial images. On these images, the radiologist identifies the pubococcygeal line (which represents the level of the pelvic floor), the H and M lines (which are helpful for confirming pelvic floor laxity), and the angle of the levator plate with the pubococcygeal line (which is helpful for identifying small bowel prolapse). In the appropriate patient, MR images provide relatively easy three-dimensional conceptualization of the pelvic floor and can significantly influence treatment planning.

Interventional and intraoperative magnetic resonance imaging

The goal of the Image Guided Therapy Program, as the name implies, is to develop the use of imaging to guide minimally invasive therapy. The program combines interventional and intraoperative magnetic resonance imaging (MRI) with high-performance computing and novel therapeutic devices. In clinical practice the multidisciplinary program provides for the investigation of a wide range of interventional and surgical procedures. The Signa SP 0.5 T superconducting MRI system (GE Medical Systems, Milwaukee, WI) has a 56-cm-wide vertical gap, allowing access to the patient and permitting the execution of interactive MRI-guided procedures. This system is integrated with an optical tracking system and utilizes flexible surface coils and MRI-compatible displays to facilitate procedures. Images are obtained with routine pulse sequences. Nearly real-time imaging, with fast gradient-recalled echo sequences, may be acquired at a rate of one image every 1.5 s with interactive image plane selection. Since 1994, more than 800 of these procedures, including various percutaneous procedures and open surgeries, have been successfully performed at Brigham and Women's Hospital (Boston, MA).

A structured system to evaluate urethral support anatomy in magnetic resonance images

OBJECTIVE

To develop a systematic method for analyzing the normal magnetic resonance imaging location and appearance of structural features involved in urethral support.

STUDY DESIGN

Multiplanar proton density magnetic resonance images of 50 nulliparous women were made at 0.5-cm intervals. The arcuate pubic ligament was the chosen reference point in all views. Structural features were located by identification of the magnetic resonance images in which they appeared. The presence or absence of urethral support structures in each scan level relative to the arcuate pubic ligament was evaluated and recorded as a graphic display. Support structures examined were the arcus tendineus fasciae pelvis, the perineal membrane, the pubococcygeal levator ani muscle and its vaginal and bony attachments, and the pubovesical muscle. Structural definitions were developed on the basis of established periurethral anatomy. Two examiners independently assessed 10 scans for interobserver concordance. This system was used in nulliparous women to quantify the location of magnetic resonance visible structures.

RESULTS

Because all levels were 0.5 cm apart, slice identification represented the distance above the arcuate pubic ligament (eg, 2 images above the arcuate pubic ligament or 1.0 cm). Interobserver concordance was 88% in identification of structure location. In the axial plane, specific structural features and relationships were localized. The frequency at which a specific structure was observed at a specific image level in all women was depicted as a gray density within the graphic display. These frequencies indicated where we would expect each structure to be located in healthy women. Relationships between structures and their attachments became apparent. Consideration of expected structural locations proven by nulliparous scans will enable us to quantitatively define abnormal structures in parous women.

CONCLUSIONS

This systematic magnetic resonance evaluation allows, for the first time, quantification of the normal anatomic location of urethral support structures. It can be used to help identify the difference between structural abnormalities and normal variation in parous women.

Dynamic magnetic resonance imaging defecography: a diagnostic alternative in the assessment of pelvic floor disorders in proctology

PURPOSE

Standard diagnostic proctologic procedures in the assessment of pelvic floor disorders include clinical evaluation and endoscopy. Particular aspects of combined pelvic floor disorders, especially those involving more than one pelvic compartment, may remain undetected without additional technical diagnostic procedures such as videoproctoscopy, cinedefecography, or colpocystodefecography. The aim of the study was to review the potentials of dynamic magnetic resonance imaging defecography to elucidate the underlying anatomic and pathophysiologic background of pelvic floor disorders in proctologic patients.

PATIENTS AND METHODS

Dynamic magnetic resonance imaging defecography was performed in 20 Patients (13 females) with main diagnoses such as rectal prolapse or intussusception, rectocele, descending perineum, fecal incontinence, outlet obstruction, and dyskinetic puborectalis muscle after clinical evaluation. The investigation was performed on a 1.5 T-magnetic resonance imaging machine in supine position. The rectum was filled with Gd-DTPA enriched ultrasound gel. First a T1/T2 weighted investigation of the pelvis was performed, followed by defecography with evacuation of the rectum. Images were obtained in a sagittal plane in a frequency of 1 image/second (true FISP) at rest and during straining. The obtained magnetic resonance imaging video tapes were analyzed off-line with cinematographic evaluation of bladder base, uterus, and anal canal position in relation to the pubococcygeal line by a blinded radiologist. Investigation time was 20 minutes.

RESULTS

In dynamic magnetic resonance imaging defecography of the pelvic floor, 12 patients with descending perineum, 10 rectoceles (10 females), 6 cystoceles (6 females), 4 enteroceles (4 females), 8 intussusceptions (5 females), and a dyskinetic puborectalis muscle in 3 males were detected. In 11 females and 3 males multifocal disorders were found, involving more than one compartment in females, whereas in males complex defects were restricted to the posterior compartment. Magnetic resonance imaging defecography revealed diagnoses consistent with clinical results in 77.3 percent and defects in addition to clinical diagnoses in combined pelvic floor disorders in 34 percent.

CONCLUSIONS

In complex pelvic floor disorders, involving more than a single defect, dynamic magnetic resonance imaging represents a convenient diagnostic procedure in females and to a lesser extent in males, in particular in terms of dynamic imaging of pelvic floor organs during defecation. In addition to the clinical assessment, dynamic magnetic resonance imaging had clinical impact in proctologic and interdisciplinary treatment.

Dynamic MRI of the pelvic floor muscles in an upright sitting position

Since the pelvic floor muscles are situated inside the pelvis, the actual function is difficult to observe. Magnetic resonance imaging (MRI) is a new method that may prove to give additional information about pelvic floor muscle function during contraction. The purpose of the present study was to assess pelvic floor muscle function during contraction and straining in an upright sitting position by use of MRI. Sixteen women, nine continent and seven with urodynamically and clinically proven genuine stress incontinence participated in the study. MRI was performed in an open-configured GE Signa SP, 0.5 T Tesla magnet. With the participants sitting in an upright position on a pelvic RF-coil, sagittal, coronal and axial T1 weighted spin echo images of the pelvic floor were obtained. During contraction and straining a scan time of 2 seconds per image for 150-250 images, was performed in a mid-sagittal plane. The results showed that the mean inward lift during contraction was 10.8 mm (SD 6.0) for all women. During straining the mean downward movement was 19.1 mm (SD 7.4). The coccyx moved in a ventral, cranial direction during contraction and was pressed in a caudal, dorsal direction during straining. It is concluded that contraction of the pelvic floor muscles is concentric, moving the coccyx in a ventral, cranial direction. The movement measured by MRI in upright sitting position is less than that concluded after clinical observation in supine position. The coccyx is pressed dorsally during straining.

Pelvic floor imaging

A greater awareness of the therapies now available for pelvic floor dysfunction has increased demand for specialized imaging of this region. Some of the techniques required are available at relatively few centers, and the purpose of this review is to introduce the emerging subspecialty of pelvic floor imaging to a more general readership. Pelvic floor anatomy is complex and is being unraveled by means of magnetic resonance (MR) imaging. This is discussed in detail by using a global, rather than a compartmentalized, anatomic approach. The physiology of normal urinary and anal function and the routine clinical tests applied to them are outlined. The imaging techniques involved include MR imaging, endosonography, and fluoroscopy. The main investigations include video urodynamic imaging, evacuation proctography, dynamic cystoproctography, dynamic MR imaging of the pelvic floor, and endoluminal imaging of the anal sphincters with MR imaging and ultrasonography. These are described in detail, and their role with regard to the main pathologic conditions of the pelvic floor--urinary and anal incontinence, constipation, and prolapse--are discussed.

Endourethral MRI

Although high-resolution MRI with phased array pelvic, endorectal, and endovaginal coils has dramatically enhanced the ability to visualize abnormalities of the female urethra and periurethral tissues, controversy still remains about the anatomy of this region. This study introduces an endourethral approach for ultra-high-resolution MRI of the female urethra and the periurethral tissues. To this end, two different radiofrequency (RF) receiver coil designs for an endourethral insertion have been developed: a single-loop coil and a phased array/quadrature coil. Both designs feature a flexible coil circuit, small loss tuning and matching directly at the coil, active decoupling, and the integration of a lambda/4 coaxial choke to decrease unbalanced currents and limit potential RF heating effects. Effective reduction of the mutual inductance between the two coils of the phased array design was achieved by introducing a metallic "paddle" to steer the flux between the coils. The performance of the coils has been evaluated in female human cadaver studies and in an in vivo pig experiment. The novel endourethral approach enabled a dramatic increase of the signal-to-noise ratio (SNR) at the region of interest (ROI). High-resolution MR images of the female urethra have been acquired with a spatial resolution down to 78 x 78 microm. Histologic correlation was achieved for the MR images generated. The achieved high local SNR and resulting high spatial resolution will add valuable information to the discussion of female urethral anatomy. Magn Reson Med 45:138-146, 2001.

Dynamic MR imaging of pelvic organ prolapse: spectrum of abnormalities

Pelvic organ prolapse is a relatively common condition in women that can have a significant impact on quality of life. Pelvic organ prolapse typically demonstrates multiple abnormalities and may involve the urethra, bladder, vaginal vault, rectum, and small bowel. Patients may present with pain, pressure, urinary and fecal incontinence, constipation, urinary retention, and defecatory dysfunction. Diagnosis is made primarily on the basis of findings at physical pelvic examination. Imaging is useful in patients in whom findings at physical examination are equivocal. Fluoroscopy, ultrasonography, and magnetic resonance (MR) imaging can be useful in evaluating pelvic organ prolapse. Advantages of MR imaging include lack of ionizing radiation, depiction of the soft tissues of the pelvic floor, and multiplanar imaging capability. Dynamic imaging is usually necessary to demonstrate pelvic organ prolapse, which may be obvious only when abdominal pressure is increased. Treatment is more likely to be successful if a survey of the entire pelvis is performed prior to therapy. Therapy is usually undertaken only in symptomatic patients. In all patients, imaging findings must be interpreted in conjunction with physical examination findings and the patient's symptoms.

Static magnetic resonance imaging of the pelvic floor muscle morphology in women with stress urinary incontinence and pelvic prolapse

In a study, the magnetic resonance imaging (MRI) findings of 69 women were analyzed to define the typical MRI appearance of the pelvic floor musculature in healthy subjects (n = 20) and women with urinary incontinence (UI) and/or genitourinary prolapse (GP) (n = 49). The following parameters were determined: thickness and signal intensity of the levator muscles on each side, distance between the urethra and symphysis, diameter of the proximal urethra, and thickness and configuration of the anterior vaginal wall. These parameters were correlated with the patients' age and parity, urodynamic parameters, and the clinical assessment of the pelvic floor. In contrast to healthy subjects, the frequent findings in women with UI and/or GP are higher signal intensity of the levator muscles (p < 0.05) and loss of the hammock-like configuration of the vagina (p < 0.01). On static MRI, the morphometry of the levator musculature identified no findings typical of either UI or GP. Analysis of MRI combined with patients' parity suggests that the severity of damage to the pelvic floor at delivery is determined by the traumatic event as such and not by the number of deliveries. Urethral diameter, distance of the symphysis to the urethra, and vaginal wall thickness cannot distinguish between controls and women with UI and/or GP. Urodynamic and functional clinical parameters do not correlate with the changes in the pelvic floor musculature demonstrated by static MRI. Although morphological changes in UI and/or GP can be demonstrated by MRI, they can be assigned a pathogenic role only if clinical symptoms are present.

Comparison of cystourethrography and dynamic MRI in bladder neck descent

PURPOSE

The purpose of this work was to test whether there are statistically significant differences between dynamic MR and lateral cystourethrogram measurement results in patients with bladder neck descent.

METHOD

Twenty-seven women (39-83 years old, mean 60.6 years old) with urinary incontinence and bladder neck descent were examined by dynamic MRI using a single shot fast spin echo sequence with half-Fourier data acquisition. Bladder neck position, angle of inclination of the urethral axis, posterior vesicourethral angle, and depth of cystoceles were measured at perineal contraction and at maximal pelvic strain. The nonparametric Wilcoxon test for paired values was used to analyze whether there were statistically significant differences between lateral cystourethrogram and dynamic MR measurement results. The Spearman correlation coefficient (rs) was calculated for all parameter pairs.

RESULTS

Measurements at maximal pelvic strain showed the greatest levels of agreement between MRI and cystourethrography. The best results were attained for the cystocele measurements (p > 0.5, rs = 0.95). Bladder neck position showed the second best agreement; if MR measurements were corrected by 0.46 cm, no statistically significant difference (p > 0.2, rs = 0.92) was calculated. Measurements at perineal contraction tallied least, probably due to the different positions adopted during the two examinations.

CONCLUSION

Measurement data on dynamic MRI for the bladder neck position and the extension of cystocele at maximal pelvic strain are comparable with lateral cystourethrogram data.

MR-based three-dimensional modeling of the normal pelvic floor in women: quantification of muscle mass

OBJECTIVE

Our objective was to use a combination of axial MR source images and three-dimensional (3D) models to describe the anatomy of the normal pelvic floor in young nulliparous women and to measure the volume of the levator ani.

SUBJECTS AND METHODS

Ten healthy nulliparous female volunteers (average age, 27 years) underwent T2-weighted MR imaging of the pelvis. Three-dimensional color-coded models of the pelvic bones and organs and the three major components of the levator ani--puborectalis, iliococcygeus, and coccygeus--were created. Source images were used to measure muscle width and signal intensity and to identify ligamentous structures. Using 3D models, we measured the volume of the levator ani, the angle of the levator plate, the posterior urethrovesical angle, and the distance of the bladder neck from the symphysis pubis and the pubococcygeal line.

RESULTS

In all volunteers, the signal intensity of the puborectalis exceeded that of the obturator externus. The average volume of the levator ani was 46.6 ml, the average width of the levator hiatus was 41.7 mm, and the average posterior urethrovesical angle was 143.5 degrees. Vaginal shape in the volunteers followed no recognizable pattern.

CONCLUSION

Muscle morphology, signal intensity, and volume is relatively uniform among healthy young women.

Pelvic floor descent: dynamic MR imaging using a half-Fourier RARE sequence

Dynamic magnetic resonance imaging (MRI) using a single shot fast spin-echo technique was evaluated as a noninvasive alternative to cystourethography or colpocystorectography in patients with pelvic organ prolapse and/or urinary incontinence. Thirty-two patients were included in this prospective study. Colpocystorectography was performed in 10 patients who previously had undergone hysterectomy and in 2 patients without history of hysterectomy with clinical suspicion of rectoceles. Bead-chain cystourethrography was performed in 20 patients without hysterectomy. For dynamic MRI, a single-slice half-Fourier RARE sequence (imaging time 2 seconds) was used to depict the pelvic organs at different levels of pelvic strain. The results obtained with dynamic MRI were correlated with the x-ray findings. All 17 cystoceles, 10 rectoceles, 2 enteroceles, and 7 vaginal prolapses could be demonstrated on MRI. Diagnostic information gained from these images was equivalent to that obtained with colpocystorectography and superior to that obtained with cystourethrography; with the latter, important findings were missed (four rectoceles). We conclude that dynamic MRI of the pelvic floor with a half-Fourier RARE sequence can reliably detect descents of all three pelvic compartments, that it requires no contrast agent, and that no radiation exposure is involved.

Pelvic floor descent: dynamic MR imaging using a half-Fourier RARE sequence

Dynamic magnetic resonance imaging (MRI) using a single shot fast spin-echo technique was evaluated as a noninvasive alternative to cystourethography or colpocystorectography in patients with pelvic organ prolapse and/or urinary incontinence. Thirty-two patients were included in this prospective study. Colpocystorectography was performed in 10 patients who previously had undergone hysterectomy and in 2 patients without history of hysterectomy with clinical suspicion of rectoceles. Bead-chain cystourethrography was performed in 20 patients without hysterectomy. For dynamic MRI, a single-slice half-Fourier RARE sequence (imaging time 2 seconds) was used to depict the pelvic organs at different levels of pelvic strain. The results obtained with dynamic MRI were correlated with the x-ray findings. All 17 cystoceles, 10 rectoceles, 2 enteroceles, and 7 vaginal prolapses could be demonstrated on MRI. Diagnostic information gained from these images was equivalent to that obtained with colpocystorectography and superior to that obtained with cystourethrography; with the latter, important findings were missed (four rectoceles). We conclude that dynamic MRI of the pelvic floor with a half-Fourier RARE sequence can reliably detect descents of all three pelvic compartments, that it requires no contrast agent, and that no radiation exposure is involved.

Patterns of prolapse in women with symptoms of pelvic floor weakness: magnetic resonance imaging and laparoscopic treatment

Magnetic resonance imaging represents a new method of imaging the pelvic viscera and pelvic floor musculature. Rapid sequences allow us to perform magnetic resonance imaging dynamically during straining or pelvic floor contraction, which can elegantly demonstrate the patterns of pelvic floor prolapse. The technique is relatively quick, noninvasive, and does not use ionizing radiation. The principle of the laparoscopic approach is to imitate the conventional abdominal or vaginal techniques. Laparoscopic sacrospinous fixation or sacral colpopexy using a graft as well as the laparoscopic repair of enteroceles and rectoceles may offer some advantages over the classic approach. As comparative prospective studies are still missing, the role of laparoscopy in the management of pelvic floor defects remains to be defined.

Open-configuration MR imaging, intervention, and surgery of the urinary tract

The open-configuration MR imaging system provides new applications both in diagnosis and in therapy of conditions in the urinary tract. In addition to conventional imaging, the open configuration permits MR imaging of patients in many positions. This has already been shown to be useful in imaging the pelvis during voiding, where a sitting position allows urodynamic evaluation. The lithotomy position can be used for imaging the prostate, which also permits procedural access. The ultimate purpose of the interventional MR imaging suite is to integrate therapeutic tools and techniques with MR imaging. From surgical planning through specialized imaging systems with minimally invasive surgical applications, new methods are being developed and implemented. This new field of image-guided therapy will require extensive clinical development and evaluation for applications in the urinary tract. This will require a large concentrated interdisciplinary effort of surgeons, radiologists, computer scientists, engineers, and physicists. Successful integration of basic research and clinical work will result in a number of cutting-edge technologies with direct clinical application in the urinary tract. Initial projects have included biopsies, endoscopies, and real-time procedural control of high-temperature and cryogenic ablations. It is anticipated that the current surge in image-guided interventions will motivate even more research activity in this field, and will ultimately define the role of MR imaging guidance in urologic intervention and surgery.