Dynamic magnetic resonance imaging for grading pelvic organ prolapse according to the International Continence Society classification: which line should be used?

Assessment of pelvic organ prolapse with the Pelvic Inclination Correction System: defining the normal range and threshold to pathology

PURPOSE

To define the normal range and threshold values for pathologic prolapse on MRI using the PICS line and assess its correlation with the pubococcygeal line (PCL).

METHODS

This prospective, IRB-approved study included 20 nulliparous volunteers and 18 prolapse patients (POP-Q Stage ≥ 2). Organ positions (bladder, cervix, anorectal junction) relative to PICS and PCL were measured on dynamic MRI. Differences in organ position were compared. Receiver-operating characteristic (ROC) analysis was performed to identify cutoff values for prolapse using the PICS line. The correlation between PICS and PCL measurements was tested with Spearman's rank correlation.

RESULTS

In volunteers, median bladder and cervix positions measured to the PICS at rest were - 2.7 cm and - 5.3 cm compared to - 1.9 cm and - 2.7 cm in patients (p < 0.001). During straining, bladder and cervix were at - 0.9 cm and - 3.2 cm in volunteers versus + 2.5 cm and + 2.5 cm in patients (p < 0.001). Correlation was strong for PICS and PCL measurements for all three compartments (δ = 0.883-0.970, p ≤ 0.001). AUCs of PICS for the anterior and middle compartment were 0.98 (95% confidence interval [CI] 0.96-1.00, p < 0.001) and 0.96 (95% CI 0.89-1.00, p < 0.001) for differentiating patients from healthy volunteers. AUC for the posterior compartment was 0.76 (95% CI 0.57-0.96, p = 0.034).

CONCLUSION

PICS measurements reliably differentiate patients from volunteers in the anterior and middle compartment. Future studies need to identify a reliable threshold for the posterior compartment. PICS and PCL measurements are strongly correlated.

POP-Q Versus Upright MRI Distance Measurements: A Prospective Study in Patients with POP

INTRODUCTION AND HYPOTHESIS

The gold standard for quantifying pelvic organ prolapse is the pelvic organ prolapse quantification (POP-Q) system; however, upright magnetic resonance imaging (MRI) is a promising new method. The objective of this study was to determine the correlation between POP-Q and MRI measurements of the bladder and cervix.

METHODS

This prospective study included patients with prolapse in whom POP-Q points Aa or Ba and C were measured as standard care. MRI scans were performed in an upright position, and the distances of the lowest points of the bladder and cervix to the Pelvic Inclination Correction System (PICS) were calculated. Correlations between POP-Q and MRI-PICS measurements were determined using the Pearson correlation coefficient for normally distributed data and the Spearman's rank correlation coefficient for non-normally distributed data.

RESULTS

A total of 63 patients were suitable for analysis. There was a moderate positive correlation between the POP-Q and MRI-PICS measurements for bladder (r(61) = 0.480, r < 0.001) and uterus (r(61) = 0.527, p < 0.001). Measurement differences between POP-Q and MRI-PICS of the bladder and uterus vary from -3.2 cm to 7.1 cm, and from -2.1 cm to 8.5 cm respectively. In 71.4% of patients more descent was seen on upright MRI than with POP-Q measurement for both bladder and uterus. For patients with similar POP-Q measurements, a high variation in MRI measurements of the bladder and uterus was found.

CONCLUSION

Despite a moderate positive correlation, upright MRI shows a larger POP extent in 71.4% of the patients than POP-Q. A high variation in MRI measurements for patients with the same POP-Q measurement was seen.

Pubococcygeal Line Versus H-line as MR Defecography Reference for Bladder Descent

INTRODUCTION AND HYPOTHESIS

Magnetic resonance defecography imaging techniques have been used widely to study pelvic floor function and diagnose pelvic organ prolapse (POP). The aim of this study was to investigate the diagnostic accuracy of the H-line to detect bladder descent compared with the current landmark, the pubococcygeal line (PCL).

METHODS

In this retrospective cohort study, patients who underwent MR defecography in our medical center and were diagnosed with moderate to severe cystocele by radiological measurements were recruited. One rest image and one maximum evacuation image for each subject were used for the following measurements: bladder base perpendicular distance from the genital hiatus (GH), indicative of clinically significant bladder descent, PCL as the current radiological reference line, and the H-line, or minimal levator hiatus line, indicative of pelvic floor muscle and connective tissue support. Subjects were categorized as having clinically significant cystocele if the "bladder base" reached within 1 cm or lower of the GH (stage II or higher cystocele). A comparison was performed to assess differences and predictive capabilities of the reference lines relative to the GH measure.

RESULTS

Seventy subjects were included, 30 with clinically significant bladder descent based on distance to GH. Women with bladder descent were older (64.0 ± 11.8 vs 51.2 ± 15.6, p < 0.001), had increased parity (3 [1-7] vs 2 [0-5], p = 0.009), and had a bladder that descended lower than the H-line at rest (1.9 ± 0.5 vs 2.2 ± 0.4, p = 0.003) and evacuation (-2.4 ± 1.6 vs -0.7 ± 1.1, p < 0.001). Multivariate regression analysis confirmed that age, length of the H-line at evacuation, the perpendicular distances between the H-line and the lowest bladder point at rest, and the PCL to the lowest bladder point at evacuation significantly correlated with bladder descent. Receiver operating characteristic analysis was used to identify a measurement threshold to diagnose clinically significant cystocele for both measurements, bladder base to the H-line: -1.2 (80.0, 72.5) area under the curve (AUC) 0.82, and bladder base PCL: -3.3 (77.8, 79.5) AUC 0.86.

CONCLUSION

Our data support the application of using the minimal levator hiatus plane and specifically the H-line as a reliable landmark to diagnose bladder descent using MR defecography imaging.

Diagnostic Value of Dynamic Magnetic Resonance Imaging (dMRI) of the Pelvic Floor in Genital Prolapses

Pelvic organ prolapse is a chronic disease resulting from a weakening of the musculoskeletal apparatus of the pelvic organs. For the diagnosis of this pathology, it is insufficient to conduct only a clinical examination. An effective diagnostic tool is the method of dynamic magnetic resonance imaging (MRI) of the pelvic floor, which allows a comprehensive assessment of the anatomical and functional characteristics of the walls of the pelvis and pelvic organs. The aim of the study was to analyze the literature data on the possibilities and limitations of using dynamic MRI in pelvic organ prolapse. The widespread use of the dynamic MRI method is due to the high quality of the resulting image, good reproducibility, and the maximum ability to display the characteristics of the pelvic floor. Dynamic MRI of the small pelvis allows a comprehensive assessment of the anatomical and functional features of the pelvis, excluding the effect of ionizing radiation on the body. The method is characterized by good visualization with high resolution and excellent soft tissue contrast. The method allows for assessing the state of the evacuation function of visualized structures in dynamics. Simultaneous imaging of all three parts of the pelvic floor using dynamic MRI makes it possible to assess multicompartment disorders. The anatomical characteristics of the state of the pelvic organs in the norm and in the event of prolapse are considered. The technique for performing the method and the procedure for analyzing the resulting images are described. The possibilities of diagnosing a multicomponent lesion are considered, while it is noted that dynamic MRI of the pelvic organs provides visualization and functional analysis of all three parts of the pelvis and often allows the choice and correction of tactics for the surgical treatment of pelvic organ prolapse. It is noted that dynamic MRI is characterized by a high resolution of the obtained images, and the advantage of the method is the ability to detect functional changes accompanying the pathology of the pelvic floor.

Pelvic Organ Prolapse

Pelvic organ prolapse (POP) is defined as the descent of one or more of the anterior and posterior vaginal walls, uterus (cervix), or apex of the vagina (vaginal vault or cuff scar after hysterectomy). Although POP can be asymptomatic, if the bulge extends beyond the opening of the vagina, it can have a significant impact on a woman's quality of life. Findings include vaginal bulging toward or through the vaginal introitus that the patient may feel, palpate, or see with a mirror. If a woman is bothered by her prolapse, she should be offered both nonsurgical and surgical treatments.

International Urogynecological Consultation: clinical definition of pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

This segment of Chapter 1 of the International Urogynecology Consultation (IUC) on pelvic organ prolapse (POP) reviews the literature on the clinical definition of POP with the intent of creating standard terminology.

METHODS

An international group containing nine urogynecologists and one university-based medical librarian performed a search of the literature using pre-specified search terms in PubMed, Embase, and Scopus. Publications were eliminated if not relevant to the clinical definition of POP, and those articles remaining were evaluated for quality using the Specialist Unit for Review Evidence (SURE). The resulting list of articles was used to inform a comprehensive review and creation of the clinical definition of POP.

RESULTS

The original search yielded 31,931 references, of which 167 were used by the writing group. Ultimately, 78 are referenced in the manuscript.

CONCLUSIONS

The clinical definition of POP for this review of the literature is: "anatomical prolapse with descent of at least one of the vaginal walls to or beyond the vaginal hymen with maximal Valsalva effort WITH the presence either of bothersome characteristic symptoms, most commonly the sensation of vaginal bulge, or of functional or medical compromise due to prolapse without symptom bother."

Magnetic resonance imaging to evaluate anterior pelvic prolapse: H line is the key

INTRODUCTION

The aim of the study is to compare clinical staging of anterior pelvic prolapse with magnetic resonance imaging (MRI) staging, using the pubococcygeal line (PCL), the midpubic line (MPL), and the H line as reference lines. Moreover, we aim to analyze interrater reliability of each reference line.

MATERIAL AND METHODS

Forty-two women with pelvic organ prolapse (POP) symptoms were studied using the pelvic organ prolapse quantification on physical examination. Two different observers calculated anterior POP using the three MRI reference lines, retrospectively. Agreement between MRI and clinical staging was estimated using Pearson correlation for the quantitative measurements and kappa index for the stages. Interrater reliability was estimated using the intraclass correlation coefficient (ICC).

RESULTS

Correlation between physical examination and the H line was high by both observers (r = 0.86 and r = 0.76, p < 0.01). The correlation was lower using MPL (r = 0.76 and r = 0.65, p < 0.01). The results of comparing MRI staging and physical examination were: κ = 0.618 and κ = 0.602 for the H line, κ = 0.273 and κ = 0.267 for MPL and κ = -0.105 and κ = -0.140 for PCL. The results of interrater reliability were: ICC of 0.968 for the H line, ICC of 0.788 for MPL, and ICC of 0.737 for PCL.

CONCLUSION

Anterior POP staging using MRI H line as a reference presents a better agreement with clinical staging than PCL or MPL. The H line has better interrater reliability. The H line could replace the current lines.

Supine magnetic resonance defecography for evaluation of anterior compartment prolapse: Comparison with upright voiding cystourethrogram

PURPOSE

To compare utility of supine Magnetic Resonance Defecography (MRD) with upright Voiding Cystourethrogram (VCUG) for evaluation of cystocele and urethral hypermobility (UHM).

METHODS

This was an IRB-approved, HIPAA-compliant, retrospective study of 51 consecutive patients with symptomatic pelvic organ prolapse (POP) and lower urinary tract symptoms who underwent both upright VCUG and supine MRD. Cystocele height was defined in centimeters with reference to the inferior edge of the pubic bone on VCUG and the pubococcygeal line on MRD. Urethral angle at rest (UAR) and during straining (UAS) was measured in degrees between the urethral axis and a vertical line at the external meatus. Pairedt-test and simple linear regression were applied to compare VCUG and MRD data sets. p <  0.05 was considered significant.

RESULTS

The mean cystocele extent was 1.58 cm lower (more inferior to the reference point) (95% CI for the mean difference: 1.21, 1.94;p < 0.0001) on MRD (-2.73 ± 1.99 cm) than on VCUG (-1.16 ± 1.75 cm). Mean UAS on MRD (72.29 ± 26.45) was 31.8 degrees higher compared to that on VCUG (40.45 ± 21.41), (95% CI for mean difference in UAS: 37.57, 26.11; p < 0.0001). Mean UAS-UAR on MRD (74.30 ± 28.50) was 58.6 degrees higher compared to that on VCUG (15.70 ± 11.27) (95% CI for mean difference in UAS-UAR 65.94, 51.26; p < 0.0001). Cystocele size was upgraded in 22 (43.3%) patients on MRD compared to VCUG. Five (9.8%) patients demonstrated UHM on VCUG; 48 (94.1%) patients demonstrated UHM on MRD. The differences between VCUG and MRD scores persisted across the range of VCUG measurements. Cystocele size was significantly larger in POP (+) patients than in POP (-) patients on MRD (p =  0.005) but not on VCUG (p =  0.06).

CONCLUSIONS

Supine MRD demonstrates significantly higher prevalence and degree of cystocele and UHM than upright VCUG, and alters the grade of bladder prolapse in a significant portion of the patient population. Cystocele size on MRD correlates with clinical presence of prolapse symptoms.

Comparison of measurement systems for posterior vaginal wall prolapse on magnetic resonance imaging

INTRODUCTION AND HYPOTHESIS

A wide variety of reference lines and landmarks have been used in imaging studies to diagnose and quantify posterior vaginal wall prolapse without consensus. We sought to determine which is the best system to (1) identify posterior vaginal wall prolapse and its appropriate cutoff values and (2) assess the prolapse size.

METHODS

This was a secondary analysis of sagittal maximal Valsalva dynamic MRI scans from 52 posterior-predominant prolapse cases and 60 comparable controls from ongoing research. All eight existing measurement lines and a new parameter, the exposed vaginal length, were measured. Expert opinions were used to score the prolapse sizes. Simple linear regressions, effect sizes, area under the curve, and classification and regression tree analyses were used to compare these reference systems and determine cutoff values. Linear and ordinal logistic regressions were used to assess the effectiveness of the prolapse size.

RESULTS

Among existing parameters, "the perineal line-internal pubis," a reference line from the inside of the pubic symphysis to the front tip of the perineal body (cutoff value 0.9 cm), had the largest effect size (1.61), showed the highest sensitivity and specificity to discriminate prolapse with area under the curve (0.91), and explained the most variation (68%) in prolapse size scores. The exposed vaginal length (cutoff value 2.9) outperformed all the existing lines, with the largest effect size (2.09), area under the curve (0.95), and R-squared value (0.77).

CONCLUSIONS

The exposed vaginal length performs slightly better than the best of the existing systems, for both diagnosing and quantifying posterior prolapse size. Performance characteristics and evidence-based cutoffs might be useful in clinical practice.

Underestimation of pelvic organ prolapse in the supine straining position, based on magnetic resonance imaging findings

Objective

Pelvic organ prolapse (POP) is clinically diagnosed in the supine position, where the effect of gravity is simulated by having the patients put strain on their pelvic floor. The objective of this study was to determine the degree of POP underestimation in the supine position based on magnetic resonance imaging (MRI) findings.

Methods

This prospective study was conducted with symptomatic POP grade ≥ 2 patients. Fifteen female patients were examined with an MRI system that allows supine and upright imaging. The differences between supine and upright in distances of the bladder neck, cervix, and pouch of Douglas from the pubococcygeal line (PCL) were estimated, together with changes in the genital hiatal area. Patients were scanned at rest and during straining. All distances were compared using the Wilcoxon ranking test.

Results

All mean distances from the PCL increased from the supine–strain to the upright–rest and from the supine–strain to the upright–strain position. These distances were found in the supine and upright positions: the bladder descended 1.3 cm to 1.4 cm, the cervix 1.1 cm to 2.2 cm, and the pouch of Douglas 0.8 cm to 1.5 cm respectively (all p values <0.05). The hiatal area was larger in the upright–strain position (mean 42.0 cm²; SD ±14.8) than during the supine–strain position (mean 33.5 cm²; SD ±14.5), with a p value of 0.02.

Conclusion

Upright MRI scanning of patients with POP grade ≥ 2 both at rest and during straining shows a significantly larger extent of the prolapse than that observed during supine straining.

Use of Dynamic MRI of the Pelvic Floor in the Assessment of Anterior Compartment Disorders

PURPOSE OF REVIEW

Approximately 25% of women in the USA suffer from pelvic floor disorders. Disorders of the anterior compartment of the pelvic floor, in particular, can cause symptoms such as incomplete urinary voiding, urinary incontinence, pelvic organ prolapse, dyspareunia, and pelvic pain, potentially negatively impacting a woman's quality of life. In some clinical situations, clinical exam alone may be insufficient, especially when patient's symptoms are in excess of their pelvic exam findings. In many of these patients, dynamic magnetic resonance imaging (dMRI) of the pelvic floor can be a valuable imaging tool allowing for comprehensive assessment of the entire pelvic anatomy and its function.

RECENT FINDINGS

Traditionally, evaluation of the anterior compartment has been primarily through clinical examination with occasional use of urodynamic testing and ultrasound. In recent years, dMRI has continued to gain popularity due to its improved imaging quality, reproducibility, and ability to display the entire pelvic floor. Emerging evidence has also shown utility of dMRI in the postoperative setting. In spite of advances, there remains an ongoing discussion in contemporary literature regarding the accuracy of dMRI and its correlation with clinical examination and with patient symptoms. Dynamic pelvic MRI is a helpful adjunct to physical examination and urodynamic testing, particularly when a patient's symptoms are in excess of the physical examination findings. Evaluation with dMRI can guide preoperative and postoperative surgical management in many patients, especially in the setting of multicompartmental disorders. This review will summarize relevant pelvic floor anatomy and discuss the clinical application, imaging technique, imaging interpretation, and limitations of dMRI.

[Preoperative functional explorations of genital prolapse (urodynamics, dynamic MRI)]

The evaluation of genital prolapse is essentially clinical; however imaging tests such as dynamic MRI or urodynamic explorations may be useful in complex cases, especially before surgical management. Dynamic MRI allows morphological and dynamic analysis of pelvic floor and levator ani function. It can also detect post-obstetric injuries, although the long-term significance of these injuries remains to be discovered. Quantification of the severity of prolapse is possible with MRI; however, the correlation of these measures with clinical examination seems poor. Its interest lies mainly in the qualitative assessment of the three stages of prolapse and the detection of elytroceles, which can be difficult to clinical examination. Urodynamics provides useful information on vesico-sphincteric function, but none of these parameters seems to be decisive in the management of prolapse.

Relevance of open magnetic resonance imaging position (sitting and standing) to quantify pelvic organ prolapse in women

INTRODUCTION

In pelvic organ prolapse (POP), posture and gravity impact organ position and symptom severity. The advanced magnet configuration in open magnetic resonance imaging (MRO) allows patients to be imaged when sitting and standing, as well in a conventional supine position. This study evaluated if sitting and standing MRO images are relevant as a means of improving quantification of POP because they allow differences in organ position not seen on supine imaging to be identified.

METHODS

Forty women recruited from a university urogynecology clinic had MRO imaging (0.5 T scanner) with axial and sagittal T2-weighted pelvic scans obtained when sitting, standing, and supine. Pelvic reference lines were used to quantify the degree of POP, and the relevance of imaging position on the detection of POP compared.

RESULTS

Images from 40 participants were evaluated (20 with POP and 20 asymptomatic controls). Our results indicate that the maximal extent of prolapse is best evaluated in the standing position using H line, M line, mid-pubic line, and perineal line as reference lines to determine POP.

CONCLUSIONS

MRO imaging of symptomatic patients in a standing position is relevant in the quantification of POP. Compared with supine images, standing imaging identifies that greater levels of downward movement in the anterior and posterior compartments occur, presumably under the influence of posture and gravity. In contrast, no appreciable benefit was afforded by imaging in the sitting position, which precluded use of some reference lines due to upward movement of the anorectal junction.

The 3D Pelvic Inclination Correction System (PICS): A universally applicable coordinate system for isovolumetric imaging measurements, tested in women with pelvic organ prolapse (POP)

In pelvic organ prolapse (POP), the organs are pushed downward along the lines of gravity, so measurements along this longitudinal body axis are desirable. We propose a universally applicable 3D coordinate system that corrects for changes in pelvic inclination and that allows the localization of any point in the pelvis at rest or under dynamic conditions on magnetic resonance images (MRI) of pelvic floor disorders in a scanner- and software independent manner. The proposed 3D coordinate system called 3D Pelvic Inclination Correction System (PICS) is constructed utilizing four bony landmark points, with the origin set at the inferior pubic point, and three additional points at the sacrum (sacrococcygeal joint) and both ischial spines, which are clearly visible on MRI images. The feasibility and applicability of the moving frame was evaluated using MRI datasets from five women with pelvic organ prolapse, three undergoing static MRI and two undergoing dynamic MRI of the pelvic floor in a supine position. The construction of the coordinate system was performed utilizing the selected landmarks, with an initial implementation completed in MATLAB. In all cases the selected landmarks were clearly visible, with the construction of the 3D PICS and measurement of pelvic organ positions performed without difficulty. The resulting distance from the organ position to the horizontal PICS plane was compared to a traditional measure based on standard measurements in 2D slices. The two approaches demonstrated good agreement in each of the cases. The developed approach makes quantitative assessment of pelvic organ position in a physiologically relevant 3D coordinate system possible independent of pelvic movement relative to the scanner. It allows the accurate study of the physiologic range of organ location along the body axis ("up or down") as well as defects of the pelvic sidewall or birth-related pelvic floor injuries outside the midsagittal plane, not possible before in a 2D reference line system. Measures in 3D can be monitored over time and may reveal pathology before bothersome symptoms appear, as well as allowing comparison of outcomes between different patient pools after different surgical approaches.

Prevalence of dynamic magnetic resonance imaging-identified pelvic organ prolapse in pre- and postmenopausal women without clinically evident pelvic organ descent

Background Dynamic magnetic resonance imaging (dMRI) is an imaging tool that can be used to evaluate and stage pelvic organ prolapse (POP). Greater understanding of the incidental detection of POP in asymptomatic patients is needed. Purpose To evaluate the prevalence of dMRI-detected POP in pre-and postmenopausal women who were imaged for reasons unrelated to pelvic floor dysfunction. Material and Methods A total of 227 women who had diagnoses that did not include POP underwent abdominal/pelvic dMRI. Patients with a positive gynecological examination for or a clinical history of POP ( n = 11), hysterectomy ( n = 4), or gynecologic-oncology surgery ( n = 2) were excluded, as well as patients who were unable to strain during MRI ( n = 11). A total of 199 patients without visible prolapse were enrolled in the study. An H-line, M-line, pubococcygeal line (PCL), and mid-pubic line (MPL) were used to detect and grade prolapse. Results The prevalence of dMRI-identified POP was higher in postmenopausal subjects. The PCL led to a greater frequency of prolapse detection than the MPL. The frequency of middle compartment descent was similar regardless of whether the PCL or MPL was used as a reference line. There was a higher incidence of prolapse in the posterior compartment. Using an H-line and PCL as references, the anterior and posterior compartments were found to significantly differ between pre- and postmenopausal subjects. The MRI parameters that were used to define POP were not correlated with parity, vaginal birth, BMI, or fetal birth weight. With respect to the MPL, age was correlated with both the presence of an elongated H-line and with descent. Conclusion Dynamic MRI identified incidental pelvic organ prolapse in asymptomatic patients. The prevalence of dMRI-detected POP was higher in postmenopausal women without visible prolapse. These findings suggest the need for further studies to identify how to modify the currently used dMRI thresholds for postmenopausal women.

Interobserver agreement of multicompartment ultrasound in the assessment of pelvic floor anatomy

OBJECTIVE

To assess the interobserver agreement of pelvic floor anatomical measurements using multicompartment pelvic floor ultrasound.

METHODS

Females were recruited from the urogynaecology/gynaecology clinics between July and October 2009 and underwent multicompartment pelvic floor ultrasonography (PFUS) using two-dimensional (2D) transperineal ultrasound (TPUS), high-frequency 2D/three-dimensional (3D) endovaginal ultrasound (EVUS) using a biplane probe with linear and transverse arrays and a 360° rotational 3D-EVUS. PFUS measurements were independently analysed by two clinicians.

RESULTS

158 females had PFUS assessment. Good-to-excellent interobserver agreement was observed for bladder-symphysis distance at rest and valsalva, urethral thickness, urethral length, urethral volume, levator hiatus area and width, anteroposterior diameter and anorectal angle. Lins Correlation was used to calculate the interobserver agreement and Bland-Altman plots were created to demonstrate the agreement between the researchers. There was also a good-to-excellent agreement between the two clinicians for the assessment of pelvic organ prolapse (POP) in the anterior, middle and posterior compartment.

CONCLUSION

Multicompartment PFUS is a reliable tool in the anatomical assessment of pelvic floor measurements and POP.

ADVANCES IN KNOWLEDGE

We found a good-to-excellent agreement between the two assessors in the assessment of pelvic floor measurements for all three pelvic floor compartments and suggest that multicompartment PFUS could be considered as a systematic integrated approach to assess the pelvic floor.

Quantitative assessment of new MRI-based measurements to differentiate low and high stages of pelvic organ prolapse using support vector machines

INTRODUCTION AND HYPOTHESIS

The objective of this study was to quantitatively assess the ability of new MRI-based measurements to differentiate low and high stages of pelvic organ prolapse. New measurements representing pelvic structural characteristics are proposed and analyzed using support vector machines (SVM).

METHODS

This retrospective study used data from 207 women with different types and stages of prolapse. Their demographic information, clinical history, and dynamic MRI data were obtained from the database. New MRI measurements were extracted and analyzed based on these reference lines: pubococcygeal line (PCL), mid-pubic line (MPL), true conjugate line (TCL), obstetric conjugate line (OCL), and diagonal conjugate line (DCL). A classification model using SVM was designed to assess the impact of the features (variables) in classifying prolapse into low or high stage.

RESULTS

The classification model using SVM can accurately identified anterior prolapse with very high accuracy (>0.90), and apical and posterior prolapse with good accuracy (0.80 - 0.90). Two newly proposed MRI-based features were found to be significant in the identification of anterior and posterior prolapse: the angle between TCL and MPL for anterior prolapse, and the angle between DCL and PCL for posterior prolapse. The overall accuracy of posterior prolapse identification increased from 47% to 80% when the newly proposed MRI-based features were taken into consideration.

CONCLUSIONS

The proposed MRI-based measurements are effective in differentiating low and high stages of pelvic organ prolapse, particularly for posterior prolapse.

ACR Appropriateness Criteria pelvic floor dysfunction

Pelvic floor dysfunction is a common and potentially complex condition. Imaging can complement physical examination by revealing clinically occult abnormalities and clarifying the nature of the pelvic floor defects present. Imaging can add value in preoperative management for patients with a complex clinical presentation, and in postoperative management of patients suspected to have recurrent pelvic floor dysfunction or a surgical complication. Imaging findings are only clinically relevant if the patient is symptomatic. Several imaging modalities have a potential role in evaluating patients; the choice of modality depends on the patient's symptoms, the clinical information desired, and the usefulness of the test. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions; they are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals, and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Dynamic Magnetic Resonance Imaging and pelvic floor disorders: how and when?

Pelvic Floor Disorders (PFD) are a major public health problem in the world and decrease seriously the patient's quality of life. In case of recurrence after surgery or complex prolapse, imaging techniques can be used. Dynamic MRI, introduced in the early 1990s, offers information of the four compartments of the pelvis with a high resolution and a direct visualization of muscles and fascias in multiple planes. But for a practical use, such an expensive exam should be well correlated to symptoms and clinical examination or change surgical approach. The aim of our review was to precise the evidence regarding techniques, and indication of dynamic MRI in the assessment of pelvic floor disorders in daily practice. The first part is a review of available studies on methods of carrying out the dynamic MRI. The second part consists on the comparison of dynamic MRI to other assessment methods in case of pelvic floor disorders. Results emphasize the lack of strong level studies about the interest of dynamic MRI in the diagnosis and surgical management of pelvic organ prolapse. Although dynamic MRI appears highly reproducible between examiners, especially for the anterior compartment, its correlation with the degree of prolapse or the symptoms appears low. The most interesting field of application seems the detection of levator ani (LA) avulsion with a higher risk of prolapse and recidive in case of LA defects. More prospective, randomized, comparative studies have to be done.

Assessment of a semiautomated pelvic floor measurement model for evaluating pelvic organ prolapse on MRI

INTRODUCTION AND HYPOTHESIS

The objective of this study was to assess the performance of a semiautomated pelvic floor measurement algorithmic model on dynamic magnetic resonance imaging (MRI) images compared with manual pelvic floor measurements for pelvic organ prolapse (POP) evaluation.

METHODS

We examined 15 MRIs along the midsagittal view. Five reference points used for pelvic floor measurements were identified both manually and using our semiautomated measurement model. The two processes were compared in terms of accuracy and precision.

RESULTS

The semiautomated pelvic floor measurement model provided highly consistent and accurate locations for all reference points on MRI. Results also showed that the model can identify the reference points faster than the manual-point identification process.

CONCLUSION

The semiautomated pelvic floor measurement model can be used to facilitate and improve the process of pelvic floor measurements on MRI. This will enable high throughput analysis of MRI data to improve the correlation analysis with clinical outcomes and potentially improve POP assessment.

On pelvic reference lines and the MR evaluation of genital prolapse: a proposal for standardization using the Pelvic Inclination Correction System

Five midsagittal pelvic reference lines have been employed to quantify prolapse using MRI. However, the lack of standardization makes study results difficult to compare. Using MRI scans from 149 women, we demonstrate how use of existing reference lines can systematically affect measurements in three distinct ways: in oblique line systems, distances measured to the reference line vary with antero-posterior location; soft issue-based reference lines can underestimate organ movement relative to the pelvic bones; and systems defined relative to the MR scanner are affected by intra- and interindividual differences in the pelvic inclination angle at rest and strain. Thus, we propose a standardized approach called the Pelvic Inclination Correction System (PICS). Based on bony structures and the body axis, the PICS system corrects for variation in pelvic inclination, at rest of straining, and allows for the standardized measurement of organ displacement in the direction of prolapse.

Dynamic magnetic resonance imaging to quantify pelvic organ prolapse: reliability of assessment and correlation with clinical findings and pelvic floor symptoms

Introduction and hypothesis

The aim of this study was to assess the interobserver agreement of magnetic resonance imaging (MRI)-based staging of pelvic organ prolapse (POP) and to quantify associations between MRI-based POP staging, findings at pelvic examination, and pelvic floor symptoms.

Methods

This was a cross-sectional study of ten symptomatic POP patients, ten symptomatic patients without POP, and ten nulliparous asymptomatic women. Three different observers performed MRI-based POP staging using the pubococcygeal line (PCL), midpubic line (MPL), perineal line, and H line as references.

Results

The interobserver agreement of MRI-based staging of the anterior and middle compartment was good to excellent. In symptomatic women without prolapse, MRI-based and pelvic-examination-based POP staging were poorly correlated. In none of the women were MRI-based POP Quantification (POP-Q) staging and pelvic floor symptoms strongly associated.

Conclusion

The interobserver agreement of MRI-based POP staging is excellent, but the added clinical value of such staging is questionable due to poor association with clinical findings and pelvic floor symptoms.

MRI diagnosis of pelvic organ prolapse compared with clinical examination

RATIONALE AND OBJECTIVES

The aims of this study were to determine agreement between clinical examination and magnetic resonance imaging (MRI) (rectal contrast and noncontrast MRI) for pelvic organ prolapse using both the pubococcygeal line (PCL) and the midpubic line (MPL) and to assess the relationship between measurements performed relative to each line.

MATERIALS AND METHODS

Dynamic MRI exams in 88 women (with rectal contrast, n = 39; noncontrast, n = 49) were evaluated, followed by review of clinical exam notes. Agreement between clinical exam and MRI and the difference between PCL and MPL measurements were evaluated.

RESULTS

Agreement of rectal contrast MRI with clinical exam was 79% for PCL and 85% for MPL (P = .17) for cystoceles, 50% for PCL and 59% for MPL (P = .20) for vaginal prolapse, 56% for PCL for enteroceles, and 61% for rectoceles. Agreement of noncontrast MRI with clinical exam was 67% for PCL and 78% for MPL (P = .19) for cystoceles, 58% for PCL and 71% for MPL (P = .10) for vaginal prolapse, 65% for enteroceles, and 40% for rectoceles. The average difference between the PCL and the MPL was 3.12 ± 0.24 cm at the bladder base and 4.88 ± 0.37 cm at the vaginal apex.

CONCLUSIONS

Agreement of MRI with clinical exam was highest for cystoceles. There was no significant difference in agreement using the MPL or PCL, suggesting that either line can be used on MRI. The average differences between the PCL and MPL at the bladder base and vaginal apex were approximately 3 and 5 cm, respectively.

Dynamic magnetic resonance imaging of pelvic organ prolapse: recent research progress

Pelvic organ prolapse (POP) refers to herniation of pelvic organs caused by the weak pelvic floor support structures. Magnetic resonance imaging (MRI) is a non-radioactive, non-invasive, fast, comprehensive, high-resolution imaging technique that has strong soft tissue contrast and can clearly show the changes of muscles and fascia structures of pelvic floor to the resting and dynamic position. It can help understand the state of pelvic organizations and provide objective imaging data for the clinical diagnosis. Dynamic MRI is commonly used for the diagnosis of bladder prolapse and swelling, uterine and vaginal prolapse, rectal prolapse and enterocele. Currently, there are no unified diagnostic criteria for POP in China. Although the US HMO system is frequently used for assessing the degree of POP, it needs to be further explored whether this system is fit for the Chinese population. In short, dynamic MRI permits a comprehensive evaluation of pelvic organ prolapse. It is an important way to study the living anatomy, shape and movement of pelvic floor. In addition to clinical evaluations, dynamic MRI (especially dynamic MRI defecography) plays a role in guiding the interdisciplinary treatment of pelvic floor dysfunction.

Motion estimation in ultrasound imaging applied to the diagnostic of pelvic floor disorders

The main purpose of this paper is to show the potential of tissue motion estimation in ultrasound imaging for the diagnostic of pelvic floor disorders. We propose to evaluate the tissue motion using a method based on a local deformable model and on image features (local phase and orientation) extracted from the monogenic signal. The proposed method is well adapted to the pelvic organ deformations and estimates motion with subpixel precision without the need for interpolation. The estimated motion is used to visualize the bladder local deformation and to extract quantitative figures such as the deformation parameters and the bladder angle variation. These results could potentially be interesting to characterize the degree of the pelvic organ prolapse.

Perineal descent and patients' symptoms of anorectal dysfunction, pelvic organ prolapse, and urinary incontinence

Introduction and hypothesis

The aim of this dynamic magnetic resonance (MR) imaging study was to assess the relation between the position and mobility of the perineum and patients’ symptoms of pelvic floor dysfunction.

Methods

Patients’ symptoms were measured with the use of validated questionnaires. Univariate logistic regression analyses were used to study the relationship between the questionnaires domain scores and the perineal position on dynamic MR imaging, as well as baseline characteristics (age, body mass index, and parity).

Results

Sixty-nine women were included in the analysis. Only the domain score genital prolapse was associated with the perineal position on dynamic MR imaging. This association was strongest at rest.

Conclusions

Pelvic organ prolapse symptoms were associated with the degree of descent of the perineum on dynamic MR imaging. Perineal descent was not related to anorectal and/or urinary incontinence symptoms.

A systematic review of clinical studies on dynamic magnetic resonance imaging of pelvic organ prolapse: the use of reference lines and anatomical landmarks

INTRODUCTION AND HYPOTHESIS

The aim of our study was to provide a systematic literature review of clinical studies on pelvic organ prolapse staging with use of dynamic magnetic resonance (MR) imaging.

METHODS

The databases EMBASE and PubMed were searched. Clinical studies were included in case they compared pelvic organ prolapse stages as assessed on dynamic MR imaging (using a reference line) with a standardized method of clinical prolapse staging.

RESULTS

Ten studies were included, which made use of seven different reference lines in relation to a wide variety of anatomical landmarks.

CONCLUSION

Only few studies have compared pelvic organ prolapse stages as assessed by dynamic MR imaging and clinical examination in a standardized manner. The available evidence suggests that prolapse assessment on dynamic MR imaging may be useful in the posterior compartment, but clinical assessment and dynamic MR imaging seem interchangeable in the anterior and central compartment.

Dynamic magnetic resonance imaging: reliability of anatomical landmarks and reference lines used to assess pelvic organ prolapse

The aim of this study was to determine the intra- and interobserver reliability of dynamic magnetic resonance (MR) staging in pelvic organ prolapse patients. In 30 patients with pelvic organ prolapse, dynamic MR images were assessed independently by two observers. Various anatomical landmarks to asses pelvic organ prolapse were used in relation to the pubococcygeal line, H-line, and mid-pubic line. Clinical measurement points were assessed in relation to the mid-pubic line. The intraclass correlation coefficients (ICC) were calculated to describe the intra- and interobserver reliability. Overall, the intra- and interobserver reliability of MR imaging measurements was excellent to good. The pubococcygeal line showed superior reliability (ICC range 0.70-0.99). The reliability of clinical measurement points, however, were only moderate (ICC range 0.20-0.96). The intra- and interobserver reliability of quantitative prolapse staging on dynamic MR imaging were good to excellent. The pubococcygeal line appears the most reliable to use.