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

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.

Clinical application of a fixed reference line in the ultrasound quantitative diagnosis of female pelvic organ prolapse

OBJECTIVE

This study explored using an improved ultrasound (US) for quantitative evaluation of the degree of pelvic organ prolapse(POP).

DESIGN

A transluminal probe was used to standardize ultrasound imaging of pelvic floor organ displacements. A US reference line was fixed between the lower edge of the pubic symphysis and the central axis of the pubic symphysis at a 30°counterclockwise angle.

METHOD

Points Aa, Ba, C and Bp on pelvic organ prolapse quantification (POP-Q) were then compared with the points on pelvic floor ultrasound (PFUS).

RESULTS

One hundred thirteen patients were included in the analysis of the standard US plane. Correlations were good in the anterior and middle compartments (PBN:Aa, ICC = 0.922; PBB:Ba, ICC = 0.923; and PC:C, ICC = 0.925), and Bland-Altman statistical maps corresponding to the average difference around the 30°horizontal line were close to 0. Correlations were poor in the posterior compartment (PRA:Bp, ICC = 0.444). However, eight (7.1%) cases of intestinal hernia and 21 (18.6%) cases of rectocele were diagnosed.

CONCLUSIONS

Introital PFUS using an intracavitary probe, which is gently placed at the introitus of the urethra and the vagina, may be accurately used to evaluate organ displacement. The application of a 30°horizontal line may improve the repeatability of the US diagnosis of POP.

Location and motion of vaginal pessaries in situ in women with successful and unsuccessful pessary treatment for pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

The objective was to compare the location and motion of pessaries between women with pelvic organ prolapse (POP) with a successful (fitting) and unsuccessful (non-fitting) pessary treatment on dynamic magnetic resonance imaging (dMRI).

METHODS

A cross-sectional exploratory study of 15 women who underwent a mid-sagittal dMRI of the pelvic floor at rest, during contraction and during Valsalva with three different types of pessaries. The coordinates of the pessaries cross section, inferior pubic point (IPP) and sacrococcygeal junction (SCJ) were obtained and the location (position, orientation) and the motion (translation and rotation) were calculated. Differences between the groups and between the pessaries within the groups were compared.

RESULTS

Nine women with a fitting pessary and 6 women with a non-fitting pessary were selected. In the non-fitting group, the pessaries were positioned more caudally and rotated more in clockwise direction and descended more, but not significantly, during Valsalva compared with the fitting group. The Falk pessary was positioned more anteriorly in the fitting group and more cranially in the non-fitting group compared with the ring and ring with support pessary.

CONCLUSIONS

A non-fitting pessary was positioned more caudally at rest; on Valsalva, it rotated more clockwise and moved more caudally, suggesting that the dynamic characteristics of the pessary might play an important role in its effectiveness. Findings of this study serve as a basis for the development of new pessary designs.

Pelvic organ movements in asymptomatic nulliparous and symptomatic premenopausal women with pelvic organ prolapse in dynamic MRI: a feasibility study comparing midsagittal single-slice with multi-slice sequences

PURPOSE

To compare multi-slice (MS) MRI sequences of the pelvis acquired at rest and straining to dynamic midsagittal single-slice (SS) sequences for the assessment of pelvic organ prolapse (POP).

METHODS

This IRB-approved prospective single-center feasibility study included 23 premenopausal symptomatic patients with POP and 22 asymptomatic nulliparous volunteers. MRI of the pelvis at rest and straining was performed with midsagittal SS and MS sequences. Straining effort, visibility of organs and POP grade were scored on both. Organ points (bladder, cervix, anorectum) were measured. Differences between SS and MS sequences were compared with Wilcoxon test.

RESULTS

Straining effort was good in 84.4% on SS and in 64.4% on MS sequences (p = 0.003). Organ points were always visible on MS sequences, whereas the cervix was not fully visible in 31.1-33.3% on SS sequences. At rest, there were no statistically significant differences of organ point measurements between SS and MS sequences in symptomatic patients. At straining, positions of bladder, cervix, and anorectum were + 1.1 cm (± 1.8 cm), - 0.7 cm (± 2.9 cm), and + 0.7 cm (± 1.3 cm) on SS and + 0.4 mm (± 1.7 cm), - 1.4 cm (± 2.6 cm), and + 0.4 cm (± 1.3 cm) on MS sequences (p < 0.05). Only 2 cases of higher-grade POP were missed on MS sequences (both with poor straining effort).

CONCLUSION

MS sequences increase the visibility of organ points compared to SS sequences. Dynamic MS sequences can depict POP if images are acquired with sufficient straining effort. Further work is needed to optimize the depiction of the maximum straining effort with MS sequences.

Quantifying the physiologic motions of the pelvic viscera during evacuation in nulligravid asymptomatic women

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) is often diagnosed during an in-office examination, which looks for motion of the vaginal wall while performing a strain maneuver. It is believed that the pelvic organs in adequately supported women are relatively stationary. This study was aimed at investigating the physiological displacements of pelvic organs using MR defecography.

METHODS

This prospective cohort study included 19 volunteers. Midsagittal slices representing rest and the maximum movement of the posterior vaginal fornix during three maneuvers were identified. Normalized axes for analysis were defined as the x' (line connecting the inferior-posterior-most point on the pubic symphysis to the anterior edge of the sacrococcygeal joint) and the y' (line orthogonal to the x axis that passed through the sacral promontory). The positions of the posterior vaginal fornix, mid-vagina, bladder neck, anorectal junction, and hymen were recorded. These subjects were then analyzed using the current radiological grading system of POP to determine any overlap between asymptomatic subjects and diagnostic ranges of POP.

RESULTS

Evacuation caused the most motion in the landmarks. The majority of the motion of the landmarks was along the y axis. The posterior vaginal fornix experienced significant descent (125% of the initial distance) without much anterior-posterior translation (7% of the initial distance) during defecation. All landmarks experienced similar trends.

CONCLUSIONS

We have shown that there is significant rotational motion of the pelvic organs around the pubic bone in adequately supported women. This motion when described using radiological grading is likely to be considered mild or moderate prolapse, which may contribute to overdiagnosis of POP.

An International Continence Society (ICS)/ International Urogynecological Association (IUGA) joint report on the terminology for the assessment and management of obstetric pelvic floor disorders

AIMS

The terminology of obstetric pelvic floor disorders should be defined and reported as part of a wider clinically oriented consensus.

METHODS

This Report combines the input of members of two International Organizations, the International Continence Society (ICS) and the International Urogynecological Association (IUGA). The process was supported by external referees. Appropriate clinical categories and a sub-classification were developed to give coding to definitions. An extensive process of 12 main rounds of internal and 2 rounds of external review was involved to exhaustively examine each definition, with decision-making by consensus.

RESULTS

A terminology report for obstetric pelvic floor disorders, encompassing 357 separate definitions, has been developed. It is clinically-based with the most common diagnoses defined. Clarity and user-friendliness have been key aims to make it usable by different specialty groups and disciplines involved in the study and management of pregnancy, childbirth and female pelvic floor disorders. Clinical assessment, investigations, diagnosis, conservative and surgical treatments are major components. Illustrations have been included to supplement and clarify the text. Emerging concepts, in use in the literature and offering further research potential but requiring further validation, have been included as an Appendix. As with similar reports, interval (5-10 year) review is anticipated to maintain relevance of the document and ensure it remains as widely applicable as possible.

CONCLUSION

A consensus-based Terminology Report for obstetric pelvic floor disorders has been produced to support clinical practice and research.

Multi-label classification of pelvic organ prolapse using stress magnetic resonance imaging with deep learning

INTRODUCTION AND HYPOTHESIS

We aimed to develop a deep learning-based multi-label classification model to simultaneously diagnose three types of pelvic organ prolapse using stress magnetic resonance imaging (MRI).

METHODS

Our dataset consisted of 213 midsagittal labeled MR images at maximum Valsalva. For each MR image, the two endpoints of the sacrococcygeal inferior-pubic point line were auto-localized. Based on this line, a region of interest was automatically selected as input to a modified deep learning model, ResNet-50, for diagnosis. An unlabeled MRI dataset, a public dataset, and a synthetic dataset were used along with the labeled image dataset to train the model through a novel training strategy. We conducted a fivefold cross-validation and evaluated the classification results using precision, recall, F1 score, and area under the curve (AUC).

RESULTS

The average precision, recall, F1 score, and AUC of our proposed multi-label classification model for the three types of prolapse were 0.84, 0.72, 0.77, and 0.91 respectively, which were improved from 0.64, 0.53, 0.57, and 0.83 from the original ResNet-50. Classification took 0.18 s to diagnose one patient.

CONCLUSIONS

The proposed deep learning-based model were demonstrated feasible and fast in simultaneously diagnosing three types of prolapse based on pelvic floor stress MRI, which could facilitate computer-aided prolapse diagnosis and treatment planning.

Analysis of long-term structural failure after native tissue prolapse surgery: a 3D stress MRI-based study

INTRODUCTION AND HYPOTHESIS

We sought to identify postoperative structural failure sites associated with long-term prolapse recurrence and their association with symptoms and satisfaction.

METHODS

Women who had a research MRI prior to native-tissue prolapse surgery were recruited for examination, 3D stress MRI, and questionnaires. Recurrence was defined by Pelvic Organ Prolapse Quantification System (POP-Q)Ba/Bp > 0 or C > -4. Measurements were performed at rest and maximum Valsalva ("strain") including vaginal length, apex location, urogenital hiatus (UGH), and levator hiatus (LH). Measures were compared between subjects and to women with normal support. Failure frequency was the proportion of women with measurements outside the normal range. Symptoms and satisfaction were measured using validated questionnaires.

RESULTS

Thirty-one women participated 12.7 years after surgery-58% with long-term success and 42% with recurrence. Failure site comparisons between success and failure were: impaired mid-vaginal paravaginal support (62% vs. 28%, p = 0.01), longer vaginal length (54% vs. 22%, p = 0.03), and enlarged urogenital hiatus (54% vs. 22%, p = 0.03). Apical paravaginal location had the lowest failure frequency (recurrence: 15% vs. success: 7%, p = 0.37). Patient satisfaction was high (recurrence: 5.0 vs. success: 5.0, p = 0.86). Women with bothersome bulge symptoms had a 33% larger UGH strain on POP-Q (p = 0.01), 8.7% larger resting UGH (p = 0.046), 11.5% larger straining LH (p = 0.01), and 9.3% larger resting LH (p = 0.01).

CONCLUSIONS

Abnormal low mid-vaginal paravaginal location (Level II), long vaginal length (Level II), and large UGH (Level III) were associated with long-term prolapse recurrence. Patient satisfaction was high and unrelated to anatomical recurrence. Bothersome bulge symptoms were associated with hiatus enlargement.

Pelvic inclination correction system for magnetic resonance imaging analysis of pelvic organ prolapse in upright position

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse quantification by means of upright magnetic resonance imaging (MRI) is a promising research field. This study determines the angle for the pelvic inclination correction system (PICS) for upright patient position, which is hypothesized to deviate from the supine PICS angle. The necessity of different PICS angles for various patient positions will also be discussed.

METHODS

Magnetic resonance scans of 113 women, acquired in an upright patient position, were used to determine the upright PICS angle, defined as the angle between the sacrococcygeal-inferior pubic point (SCIPP) line and the horizontal line. The difference and correlation between the upright and supine PICS angles were calculated using the paired Student's t-test and the Pearson's correlation coefficient (r) respectively. The effect of the difference between the upright and supine PICS angle on the measured pelvic organ extent was calculated using goniometry.

RESULTS

The mean (interquartile range) PICS angles were 29° (26-35°) for the upright and 33° (30-37°) for the supine patient position. They were significantly different (p<0.001) and very strongly correlated (r = 0.914, p<0.001). The 4° difference between the average upright and supine PICS angle results in an average underestimation of the measured cervix height of approximately 0.5 cm for patients scanned in upright position.

CONCLUSIONS

The PICS angle for the upright patient position is 29°. The use of a dedicated PICS angle for different patient positions allows for more accurate pelvic organ extent analysis in patients with prolapse.

The feasibility of uterine-vaginal axis MRI-based as evaluation of surgical efficacy in women with pelvic organ prolapse

Background

The aim of this study was to provide a potential surgical efficacy assessment in the treatment of pelvic organ prolapse (POP).

Methods

A retrospective cohort study was performed on magnetic resonance imaging (MRI) imaging data of 16 non-prolapsed (control group) and 30 preoperative and postoperative POP (case group) women from 2019 to 2021 at the First Affiliated Hospital of Kunming Medical University. MRI diagnoses and measures of the relevant anatomical points at rest were used to analyze the healthy control data and the data from POP women before and after surgery.

Results

The middle vaginal-PICS line angle (78.12°±15.03° vs. 69.35°±11.51°, 78.12°±15.03° vs. 61.56°±9.58°, P<0.05) and the middle-lower vaginal angle (179.30°±12.96° vs. 161.73°±10.42°, 179.30°±12.96° vs. 147.01°±12.20°, P<0.05) in the preoperative group were significantly larger than those in the control and postoperative groups. Y-axis coordinates of the endocervical orifice (−52.39±15.63 vs. −59.04±11.49 mm, −52.39±15.63 vs. −65.27±7.25 mm, P<0.05), posterior vaginal fornix (−34.25±13.30 vs. −46.69±11.09 mm, −34.25±13.30 vs. −49.93±8.02 mm, P<0.05), the junction of the middle and lower vagina (−0.48±8.65 vs. −11.34±7.33 mm, −0.48±8.65 vs. −10.11±9.77 mm, P<0.05), and anterior vaginal fornix (−23.14±13.71 vs. −34.68±9.07 mm, −23.14±13.71 vs. −38.64±6.48 mm, P<0.05), as well as the x-axes of the junction of the middle and lower parts of the vagina (26.79±6.71 vs. 19.56±5.24, 26.79±6.71 vs. 17.67±5.81, P<0.05), and vaginal introitus (23.39±7.12 vs. 18.55±4.22, 23.39±7.12 vs. 19.00±4.55, P<0.05) in the preoperative group were smaller than those of the control and postoperative groups. Differences between the control and postoperative groups were not statistically significant (P>0.05).

Conclusions

The current study established that the uterine-vaginal axis of POP women moved backward and downward in the coordinate system, as shown on MRI sagittal images. Further, it moved forward and upwards after surgical repair and more closely resembled that of the control group. The uterine-vaginal axis may provide an evaluation of surgical efficacy in women with POP.

Magnetic resonance imaging evaluation of the effectiveness of FemiCushion in pelvic organ prolapse

Aims

FemiCushion (FC) is a supportive device for pelvic organ prolapse (POP), but its effectiveness has not been evaluated with imaging studies. This study utilized magnetic resonance imaging (MRI) to evaluate the anatomic changes induced by FC use in patients with severe POP.

Methods

This prospective study examined patients with stage 3 or 4 POP who underwent treatment with FC and received a diagnostic MRI. Measurements were made in the midsagittal plane at rest and during straining with and without FC. The vertical distances from the lowest points of the anterior and posterior vaginal wall (A; P), uterine cervix or vaginal stump (C), and perineal body (PB) to the Pelvic Inclination Correction System line were measured, along with the lengths of the urogenital (UGH) and levator hiatus (LH).

Results

Twelve patients were included in the study. The median age was 72 (range, 56–84) years. All reference points were positioned significantly higher with the FC than without the FC (median ΔA: 11 mm, p = 0.005; ΔC: 14 mm, p = 0.011; ΔP: 6 mm, p = 0.008; ΔPB: 7 mm, p = 0.002). Median UGH and LH lengths during straining were significantly shorter with the FC than without the FC (UGH: 44 mm vs. 53 mm, p = 0.002; LH: 60 vs. 65 mm, p = 0.021).

Conclusions

This is the first report on the use of MRI to measure the performance of FC. Our study demonstrates that FC effectively repositioned the organs involved in POP.

Comparison of the Axes and Positions of the Uterus and Vagina Between Women With and Without Pelvic Floor Organ Prolapse

Purpose

To analyze the role of the axial positions of the uterus and vagina in providing pelvic floor support, encourage evaluations of pelvic floor function, and improve the understanding of the pathogenesis of pelvic organ prolapse.

Methods

The lengths and angles of the upper, middle, and lower axes of the vagina, uterine body, and cervix of 81 women with prolapse (prolapse group) and 57 women without prolapse (non-prolapse group) were measured and compared using magnetic resonance images. The pelvic inclination correction system (PICS) line was also compared between the groups. The coordinate parameters of the anatomical points of the uterus and vagina were measured, and their positions were analyzed.

Results

In the prolapse group, the uterine body-cervical angle, cervical-upper vaginal angle, uterine body-PICS line angle, cervical-PICS line angle, and lower vaginal-PICS line angle were smaller (p < 0.05) and the middle-lower vaginal angle, upper vaginal-PICS line angle, and middle vaginal-PICS line angles were larger (p < 0.05) than those in the non-prolapse group. The cervical length was longer (p < 0.05) and the middle and lower vaginal lengths were shorter (p < 0.05) in the prolapse group. The coordinate system revealed that the uterine and vaginal axes were shifted backward and downward in the prolapse group.

Conclusion

Patients in the prolapse group were more likely to have retroversion and retroflexion of the uterus than those in the non-prolapse group. The vagina was shortened, turned forward, and straightened, and the uterus and vagina were shifted backward and downward in the prolapse group. Changes in the axial position of the uterus and vagina are important mechanisms of pelvic floor organ prolapse.

Preoperative level II/III MRI measures predicting long-term prolapse recurrence after native tissue repair

INTRODUCTION AND HYPOTHESIS

To identify preoperative level II/III MRI measures associated with long-term recurrence after native tissue prolapse repair.

METHODS

Women who previously participated in pelvic floor research involving MRI prior to undergoing primary native tissue prolapse repair were recruited to return for repeat examination and MRI. Recurrence was defined by POP-Q (Ba/Bp > 0 or C > -4), repeat surgery, or pessary use. Preoperative MR images were used to perform five level II/III measurements including a new levator plate (LP) shape analysis at rest and maximal Valsalva. Principal component analysis (PCA) was used to evaluate LP shape variations. Principal component scores calculated for two independent shape variations were noted.

RESULTS

Thirty-five women were included with a mean follow-up of 13.2 ± 3.3 years. Nineteen (54%) were in the success group. There were no statistical differences between success versus recurrence groups in demographic, clinical, or surgical characteristics. Women with recurrence had a larger preoperative resting levator hiatus [median 6.4 cm (IQR 5.7, 7.1) vs. 5.8 cm (IQR 5.3, 6.3), p = 0.03]. This measure was associated with increased odds of recurrence (OR 8.2, CI 1.4-48.9, p = 0.02). Using PCA, preoperative LP shape PC1 scores were different between success and recurrence groups (p = 0.02), with a more dorsally oriented LP shape associated with recurrence.

CONCLUSIONS

Larger preoperative levator hiatus at rest and a more dorsally oriented levator plate shape were associated with prolapse recurrence at long-term follow-up. For every 1 cm increase in preoperative resting levator hiatus, the odds of long-term prolapse recurrence increases 8-fold.

A new 3D stress MRI measurement strategy to quantify surgical correction of prolapse in three support systems

AIMS

The aim of this study was to develop and test the feasibility of a magnetic resonance imaging (MRI)-based measurement strategy to evaluate the effectiveness of surgical procedures in restoring normal anatomy in all three systems of pelvic floor support and quantify the structural changes induced by prolapse surgery.

METHODS

Patients underwent clinical examination and stress MRI preoperatively and again 3 months postoperatively. Preoperative and postoperative measures of three MRI-based structural support systems were made: (1) vaginal wall, (2) apical and paravaginal support, and (3) hiatal closure system. Preoperative to postoperative structural changes were calculated and compared to normal values, and bivariate associations were determined.

RESULTS

The three structural support systems were successfully quantified for both preoperative and postoperative MRIs regardless of operative approaches in all 15 women in the pilot group. Apical support was restored to normal in 11 of 12 patients who underwent an apical suspension procedure and 9 of 14 patients with a posterior repair had normalization of genital hiatus size. Mid-vaginal paravaginal location was elevated an average of 2.5 ± 2.0 cm despite no paravaginal repairs being performed. Paravaginal location improvements were also significantly correlated with apical elevation (r values 0.99-0.87, p < 0.001).

CONCLUSIONS

A strategy that quantifies structural-specific preoperative impairments and improvements after prolapse surgery was successfully developed. Early findings reveal that prolapse surgery is more successful in restoring normal anatomy at Level I than Level III. Improvement in paravaginal location is significantly correlated with apical elevation.

The establishment of a 3D anatomical coordinate system for defining vaginal axis and spatial position

BACKGROUND AND OBJECTIVE

Pelvic organ prolapse (POP), the herniation of the pelvic organs toward the vaginal opening, is a common pelvic floor disorder (PFD) whose etiology is poorly understood. Traditional methods for evaluating POP are often constrained to external vaginal examination, limited to 2D, or have poor reproducibility. We propose a reliable 3D anatomic coordinate system for standardized 3D assessment of pelvic anatomy using magnetic resonance imaging (MRI).

METHODS

The novel 3D anatomic reference system is based on six bony landmarks of the pelvis manually identified in MRI: the ischial spines and the superior and inferior pubic points of the left and right pubic symphysis. The origin of this system is defined as the midpoint of the ischial spines. The reproducibility and applicability of the pelvic coordinate system were evaluated by (1) implementing it in a new method to quantify vaginal position and axis (angulation) in 3D space from MRI segmentations of the vagina and (2) computing the intraclass correlation (ICC) on coordinate system and vaginal measures. The MRI analysis was performed by four non-medically trained observers on five pelvic MRI datasets on approximately five separate occasions.

RESULTS

Overall, all bony landmarks had excellent intra-observer reliability and inter-observer reliability (ICC>0.90); intra-observer reliability was moderate-to-good among the vaginal position parameters (0.5<ICC≤0.90) and moderate for the vaginal axis angles (0.50<ICC≤0.75); inter-observer reliability was moderate in the vaginal position coordinates and vaginal axis measures. On average, within-observer differences in the vaginal position and angle measures relative to the overall mean were <1 mm and <1°, respectively.

CONCLUSIONS

The proposed anatomic coordinate system and vaginal analysis approach allow quantitative assessment of pelvic anatomy that is robust to the experience level of the observer. The application of these methods in radiographic studies will give new insight into the underlying anatomic changes involved in the pathogenesis of POP and other PFDs and help better understand their etiology.

Association between overactive bladder and pelvic organ mobility as evaluated by dynamic magnetic resonance imaging

Overactive bladder (OAB) is a prevalent condition, which negatively impacts patients’ quality of life. Pelvic organ prolapse (POP), also prevalent in women, has been recognized as an important etiology of female OAB, although the pathophysiological mechanisms remain controversial. In this study, we reviewed findings of dynamic magnetic resonance imaging (dMRI) in 118 patients with POP and investigated the association between dMRI findings, including positions and mobilities of pelvic organs as well as parameters of pelvic organ support and bladder outlet obstruction (urethral kinking), and OAB in order to elucidate the pathophysiology of OAB in patients with POP. Our results showed that compared with non-OAB patients, OAB patients had a significantly higher body mass index, more severe pelvic floor muscle impairment, and more profound supportive defects in the uterine cervix (apical compartment). On the other hand, dMRI parameters showed hardly any significant difference between patients with mild and moderate to severe OAB. These findings may imply that levator ani impairment and defective supports of the apical compartment could be associated with the presence of OAB and that the severity of OAB could be affected by factors other than those related to pelvic organ mobility and support or urethral kinking.

Structural failure sites in posterior vaginal wall prolapse: stress 3D MRI-based analysis

INTRODUCTION AND HYPOTHESIS

The objective was to identify structural failure sites in rectocele by comparing women with and those without posterior vaginal wall prolapse and accessing their relative contribution to rectocele size based on stress MRI-based measurements.

METHODS

We studied three-dimensional stress MRI at maximal Valsalva of 25 women with (cases) and 25 without (controls) posterior vaginal prolapse of similar age and parity. Vaginal wall factors (posterior wall length and width); attachment factors (paravaginal posterior wall location, posterior fornix height, and perineal height); and hiatal factors (hiatal size and levator ani defects) were measured using Slicer 4.3.0® and a custom Python program. Stepwise linear regression was used to assess the relative contribution of all factors to the posterior prolapse size.

RESULTS

We identified three primary factors with large effect sizes of 2 or greater: two attachment factors-posterior paravaginal descent and perineal height; and one hiatal factor-genital hiatus size. These were the strongest predictors of the presence and size of rectocele, the most common failure sites, found in 60-76% of cases; and highly correlated with one another (r = 0.72-0.84, p < .001). Longer vaginal length, wider distal vagina, lower posterior fornix, and larger levator ani hiatus had smaller effect sizes and were less likely to fall outside the norm (20-24%) than the three primary factors. When considering all the supporting factors, the combination of perineal height, posterior fornix height, and vaginal length explained 73% of the variation in rectocele size.

CONCLUSIONS

Lower perineal and lateral posterior vaginal location and enlarged genital hiatus size were strong predictors of rectocele occurrence and size and correlated highly.

Feasibility of a deep learning-based method for automated localization of pelvic floor landmarks using stress MR images

INTRODUCTION AND HYPOTHESIS

Magnetic resonance imaging (MRI) plays an important role in assessing pelvic organ prolapse (POP), and automated pelvic floor landmark localization potentially accelerates MRI-based measurements of POP. Herein, we aimed to develop and evaluate a deep learning-based technique for automated localization of POP-related landmarks.

METHODS

Ninety-six mid-sagittal stress MR images (at rest and at maximal Valsalva) were used for deep-learning model training and generalization testing. We randomly split our dataset into a training set of 73 images and a testing set of 23 images. One soft-tissue landmark (the cervical os [P1]) and three bony landmarks (the mid-pubic line [MPL] endpoints [P2&P3] and the sacrococcygeal inferior-pubic point [SCIPP] line endpoints [P3&P4]) were annotated by experts. We used an encoder-decoder structure to develop the deep learning model for automated localization of the four landmarks. Localization performance was assessed using the root square error (RSE), whereas the reference lines were assessed based on the length and orientation differences.

RESULTS

We localized landmarks (P1 to P4) with mean RSEs of 1.9 mm, 1.3 mm, 0.9 mm, and 3.6 mm. The mean length errors of the MPL and SCIPP line were 0.1 and -2.1 mm, and the mean orientation errors of the MPL and SCIPP line were -0.7° and -0.3°. Our method predicted each image in 0.015 s.

CONCLUSIONS

We demonstrated the feasibility of a deep learning-based approach for accurate and fast fully automated localization of bony and soft-tissue landmarks. This sped up the MR interpretation process for fast POP screening and treatment planning.

Dynamic magnetic resonance imaging to quantify pelvic organ mobility after treatment for uterine descent: differences between surgical procedures

INTRODUCTION AND HYPOTHESIS

Pelvic organ mobility is defined as the displacement of pelvic organs between rest and maximal straining. We hypothesized that pelvic organ mobility after vaginal sacrospinous hysteropexy (SSHP) might be increased compared with other surgeries for uterine descent, which may contribute to the high occurrence of postoperative cystocele after this surgery. Pelvic organ mobility and the vaginal axes after SSHP are compared with other surgical procedures for uterine descent: vaginal hysterectomy with uterosacral suspension (VH) and laparoscopic sacrohysteropexy (LSH).

METHODS

In this prospective pilot study, 15 women were included (5 for each procedure). Six months postoperatively, POP-Q examination and dynamic MRI were performed and questionnaires were filled out regarding prolapse complaints. Pelvic organ mobility on MRI was defined as vertical displacement of pelvic organs at rest and maximal straining. The displacements and angles were measured using an image registration method. Furthermore, the angle of displacement of cervix/vaginal vault and vaginal axes were assessed.

RESULTS

No anatomical recurrences of pelvic organ prolapse were found. No difference in pelvic organ mobility was demonstrated. After VH, a more posterior position of the upper vagina was found compared with SSHP and LSH.

CONCLUSIONS

Based on these data, the higher recurrence risk in the anterior compartment after SSHP cannot be explained. Larger sample sizes, studying women with recurrence or de novo cystocele after SSHP or using an upright MRI scanner would be of interest to further assess the relationship between pelvic organ mobility and the occurrence of anterior vaginal wall prolapse.

Aging effects on pelvic floor support: a pilot study comparing young versus older nulliparous women

INTRODUCTION AND HYPOTHESIS

We sought to determine age-related changes to the pelvic floor in the absence of childbirth effects.

METHODS

A case-control study was conducted from June 2017 to August 2018 comparing two groups of nulliparous women: <40 years old and ≥ 70 years old. Clinical evaluation included POP-Q, instrumented speculum testing, and handgrip strength. Dynamic 3D-stress MRI was performed on all women to obtain genital and levator hiatus (LH) lengths, LH area, and levator bowl volume. LH shape was quantified using a novel measure called the "V-U index." Pubovisceral muscle (PVM) cross-sectional area (CSA) was also measured. Bivariate comparisons between the two groups were made for all variables. Effect sizes were calculated for MRI measurements.

RESULTS

Twelve young and 9 older nulliparous women were included. Levator bowl volume at rest was 83% larger in older women (108.0 ± 34.5 cm³ vs 59.2 ± 19.3 cm³, p = 0.001, d = 1.82). MRI genital hiatus at rest was larger among the older group (2.7 ± 0.6 cm vs 3.5 ± 0.6 cm, p = 0.007, d = 1.34). V-U index, a measure of LH shape where 0 = "V" and 1 = "U," differed between groups indicating a more "U"-like shape among older women (0.71 ± 0.23 vs 0.35 ± 0.18, p = 0.001, d = 1.72). Handgrip strength was lower in the older vs young group (23.2 ± 5.2 N vs 33.4 ± 5.2 N, p < 0.0001); however, the Kegel augmentation force and PVM CSA were similar (3.2 ± 1.1 N vs 3.3 ± 2.2 N, p = 0.89, and 0.8 ± 0.3 cm² vs 0.7 ± 0.2 cm², p = 0.23 respectively).

CONCLUSIONS

Levator bowl volume at rest was over 80% larger among older women, reflecting a generalized posterior distension with age.

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.

3D reconstruction of MR-visible Fe3 O4 -mesh implants: Pelvic mesh measurement techniques and preliminary findings

AIMS

To develop MR-based measurement technique to evaluate the postoperative dimension and location of implanted magnetic resonance (MR)-visible meshes.

METHODS

This technique development study reports findings of six patients (A-F) with cystoceles treated with anterior vaginal MR-visible Fe₃ O₄ -polypropylene implants. Implanted meshes were reconstructed from 3 months and/or 1 year postsurgical MR-images using 3D Slicer®. Measurements including mesh length, distance to the ischial spines, pudendal, and obturator neurovascular bundles and urethra were obtained using software Rhino® and a custom Matlab® program. The range of implanted mesh length and their placements were reported and compared with mesh design and implantation recommendations. With the anterior/posterior-mesh-segment-ratio mesh shrinkage localization was evaluated.

RESULTS

Examinations were possible for patients A-D 3 months and for A, C, E, and F 1 year postsurgical. The mesh was at least 40% shorter in all patients 3 months and/or 1 year postoperatively. A, B showed shrinkage in the anterior segment, D, E in the posterior segment (Patients C, F not applicable due to intraoperative mesh trimming). Patient E presented pain in the area of mesh shrinkage. In Patient C posterior mesh fixations were placed in the iliococcygeal muscle rather than sacrospinous ligaments. Arm placement less than 20 mm from the pudendal neurovascular bundles was seen in all cases. The portion of the urethra having mesh underneath it ranged from 19% to 55%.

CONCLUSIONS

MRI-based measurement techniques have been developed to quantify implanted mesh location and dimension. Mesh placement variations possibly correlating with postoperative complications can be illustrated.

Five-year outcome after pelvic floor reconstructive surgery: evaluation using dynamic magnetic resonance imaging compared to clinical examination and quality-of-life questionnaire

Background Dynamic magnetic resonance imaging (dMRI) captures the entire pelvis during Valsalva maneuver and helps diagnosing pelvic floor changes after reconstructive surgery. Purpose To evaluate therapeutic outcome five years after reconstructive surgery using clinical examination, dMRI, and quality-of-life (QOL) questionnaire. Material and Methods Clinical examination, dMRI, and QOL questionnaire were conducted before surgery and in the follow-ups at 12 weeks, one year, and five years in women with pelvic organ prolapse (POP) stage ≥2. dMRI was performed at 1.5-T using a predefined protocol including sagittal T2-weighted (T2W) sequence at rest and sagittal T2W true-FISP sequence at maximum strain for metric POP measurements (reference points = bladder, cervix, pouch, rectum). Pelvic organ mobility (POM) was defined as the difference of the metric measurement at maximum strain and at rest. Results Twenty-six women with 104 MRI examinations were available for analysis. dMRI results mostly differ to clinical examination regarding the overall five-year outcome and the posterior compartment in particular. dMRI diagnosed substantially more patients with recurrent or de novo POP in the posterior compartment (n = 17) compared to clinical examination (n = 4). POM after five years aligns to preoperative status except for the bladder. POM reflects best the QOL results regarding defecation disorders. Conclusion A tendency for recurrent and de novo POP was seen in all diagnostic modalities applied. dMRI objectively visualizes the interaction of the pelvic organs and the pelvic floor after reconstructive surgery and POM correlated best with the women's personal impression on pelvic floor complaints.

Translabial Ultrasound Evaluation of Pelvic Floor Structures and Mesh in the Urology Office and Intraoperative Setting

BACKGROUND

Translabial ultrasound (TUS) can provide an inexpensive alternative imaging modality for evaluating pelvic floor structures and synthetic slings as mesh can be difficult to identify on pelvic exam or cystoscopy, patients may be unable to provide an accurate history of previous pelvic surgery, and cross-sectional imaging with computed tomography and magnetic resonance imaging can be inadequate for evaluating synthetic slings.

OBJECTIVE

To demonstrate the use of TUS in the evaluation of female pelvic floor structures and mesh.

METHODS

Translabial ultrasound can be used in the Urology clinic or intraoperative setting using a curvilinear transducer. Following identification of anatomic landmarks in the various planes of the pelvic floor, TUS can evaluate for pelvic floor disorders and the type and location of synthetic mesh material. Artifacts, such as air pockets in the vagina or rectum and the hypoechoic pubic symphysis, are also considered.

RESULTS

Real-time imaging allows for dynamic examination of pelvic organ prolapse and urethral hypermobility that can contribute to pelvic exam findings. Bladder ultrasound can help evaluate for lesions, calculi, and even mesh erosion. Translabial ultrasound can also be used to differentiate hyperechoic retropubic and transobturator slings by identifying the position of sling arms and the appearance of the sling at different planes. Evaluation with TUS can demonstrate sling disruption, folding, urethral impingement, and erosion into pelvic floor structures. This can be particularly useful in patients presenting with pain, recurrent infections, or voiding dysfunction in which problems with mesh may not be easily identified on pelvic exam or cystoscopy. This imaging modality can complement a patient's history, aid in preoperative planning, and enable intraoperative identification of mesh slings.

CONCLUSION

Translabial ultrasound provides a quick, readily available, and easy-to-learn imaging modality for evaluating pelvic floor structures and mesh in the office or intraoperative setting.

Technique development and measurement of cross-sectional area of the pubovisceral muscle on MRI scans of living women

INTRODUCTION AND HYPOTHESIS

Measurements of the anatomic cross-sectional area (CSA) of the pubovisceral muscle (PVM) in women are confounded by the difficulty of separating the muscle from the adjacent puborectal (PRM) and iliococcygeal (ICM) muscles when visualized in a plane orthogonal to the fiber direction. We tested the hypothesis that it might be possible to measure the PVM CSA within a defined region of interest based on magnetic resonance images (MRI).

METHODS

MRI scans of 11 women with unilateral PVM tears and seven primiparous women with intact muscles following elective C-section were used to identify the PVM injury zone defined by the mean location of its boundaries with the adjacent intact PRM and ICM from existing anatomic reference points using 3D Slicer and ImageJ software. Then, from the 15 or more 2-mm transverse slices available, the slice with the maximum anatomic CSA of the left and right PVM was found in 24 primiparous women with bilaterally intact muscles who had delivered via C-section.

RESULTS

Mean [± standard deviation (SD)] of the maximum left or right PVM cross-section areas for the 24 women, measured by two different raters, was 1.25 ± 0.29 cm² (range 0.75-1.86). The 5th, 50th, and 95th percentile values were 0.77, 1.23, and 1.80 cm², respectively. Inter- and intrarater measurement repeatability intraclass correlation coefficients exceeded 0.89 and 0.90, respectively.

CONCLUSIONS

It is possible to use MRI to identify the volume of interest with the maximum anatomic cross section of the PVM belly while minimizing the inadvertent inclusion of adjacent PRM or ICM in that measurement.

Influence of adequate pelvic floor muscle contraction on the movement of the coccyx during pelvic floor muscle training

[Purpose] Pelvic floor muscle training is a first-line therapy for female stress urinary incontinence. Previous studies have suggested that the coccyx tip moves ventrally and cranially during pelvic floor muscle contraction. The study aimed to elucidate the influence of adequate pelvic floor muscle contraction on coccyx movement. [Subjects and Methods] Sixty-three females (57 patients with stress urinary incontinence and additional 6 healthy volunteers) were enrolled. Using magnetic resonance imaging, coccyx movement was evaluated during pelvic floor muscle contraction and strain. An adequate contraction was defined as a contraction with good Oxford grading scale [≥3] and without inadequate muscle substitution patterns. [Results] Inadequate muscle substitution patterns were observed in 33 participants (52.4%). No significant difference was observed in the movement of the coccyx tip in the ventrodorsal direction between females with and without inadequate muscle substitution patterns. However, a significant increase in the movement of the coccyx tip in the cranial direction was detected in the group without inadequate muscle substitution patterns. Compared to participants with inadequate pelvic floor muscle contraction, those who had adequate pelvic floor muscle contraction exhibited significantly increased cranial movement of the coccyx. [Conclusion] Adequate pelvic floor muscle contraction can produce cranial movement of the coccyx tip.

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.

Structural Failure Sites in Anterior Vaginal Wall Prolapse: Identification of a Collinear Triad

OBJECTIVE

To test the null hypothesis that six factors representing potential fascial and muscular failure sites contribute equally to the presence and size of a cystocele: two vaginal attachment factors (apical support and paravaginal defects), two vaginal wall factors (vaginal length and width), and two levator ani factors (hiatus size and levator ani defects).

METHODS

Thirty women with anterior-predominant prolapse (women in a case group) and 30 women in a control group underwent three-dimensional stress magnetic resonance imaging. The location of the anterior vaginal wall at maximal Valsalva was identified with the modified Pelvic Inclination Coordinate System and the six factors measured. Analysis included repeated-measure analysis of variance, logistic regression, and stepwise linear regression.

RESULTS

We identified a collinear triad consisting of apical location, paravaginal location, and hiatus size that were not only the strongest predictors of cystocele size, but were also highly correlated with one another (r=0.84-0.89, P<.001) for the presence and size of the prolapse. Together they explain up to 83% of the variation in cystocele size. Among the less significant vaginal factors, vaginal length explained 19% of the variation in cystocele size, but no significant difference in vaginal width existed. Women in the case group were more likely to have abnormalities in collinear triad factors (up to 80%) than vaginal wall factors (up to 23.3%). Combining the strongest collinear triad with the vaginal factors, the model explained 92.5% of the variation in cystocele size.

CONCLUSION

Apical location, paravaginal location, and hiatus size are highly correlated and are strong predictors of cystocele presence and size.

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.

Quantitative analyses of variability in normal vaginal shape and dimension on MR images

INTRODUCTION AND HYPOTHESIS

We present a technique for quantifying inter-individual variability in normal vaginal shape, axis, and dimension, and report findings in healthy women.

METHODS

Eighty women (age: 28∼70 years) with normal pelvic organ support underwent supine, multi-planar proton-density MRI. Vaginal width was assessed at five evenly-spaced locations, and vaginal axis, length, and surface area were quantified via ImageJ and MATLAB.

RESULTS

The mid-sagittal plane angles, relative to the horizontal, of three vaginal axes were 90 ± 11, 72 ± 21, and 41 ± 22° (caudal to cranial, p < 0.001). The mean (± SD) vaginal widths were 17 ± 5, 24 ± 4, 30 ± 7, 41 ± 9, and 45 ± 12 mm at the five locations (caudal to cranial, p < 0.001). Mid-sagittal lengths for anterior and posterior vaginal walls were 63 ± 9 and 98 ± 18 mm respectively. The vaginal surface area was 72 ± 21 cm(2) (range: 34 ∼ 164 cm(2)). The coefficient of determination between any demographic variable and any vaginal dimension did not exceed 0.16.

CONCLUSIONS

Large variations in normal vaginal shape, axis, and dimensions were not explained by body size or other demographic variables. This variation has implications for reconstructive surgery, intravaginal and surgical product design, and vaginal drug delivery.

One-year dynamic MRI follow-up after vaginal mesh repair: evaluation of clinical, radiological, and quality-of-life results

BACKGROUND

Pelvic organ prolapse (POP) is a common disorder in elderly women often surgically repaired with alloplastic meshes; yet knowledge of the pelvic floor behavior and multi-compartment defects postoperatively is scarce.

PURPOSE

To evaluate the 1-year outcome after mesh repair in patients with POP using clinical examination (CE), dynamic magnetic resonance imaging (dMRI), and the prolapse quality-of-life (P-QOL) questionnaire.

MATERIAL AND METHODS

A prospective observational study was conducted of 69 women undergoing pelvic mesh surgery. Clinical examination, dMRI, and the P-QOL questionnaire were applied before and after surgery to evaluate POP. Mean outcome measures were POP outcome as determined on clinical and dMRI examinations and its impact on quality of life. Statistical results were obtained with SPSS version 15.0. ANOVA was used to compare pre-/postsurgical quality of life data.

RESULTS

Sixty-nine women (mean age, 64.75 years; BMI, 26.75 kg/m(2); postmenopausal, 89.2%) were recruited and treated with Seratom® or Perigee™ mesh implants. A significant improvement in the position of bladder neck, vaginal vault/uterus, pouch of Douglas, and rectum was found 12 weeks and 1 year after surgery using POP-Q scale and dMRI. Advanced cystoceles and enteroceles seem underestimated by CE using the POP-Q system compared to dMRI results (P = 0.003 and P < 0.001), vice versa dMRI overestimated POP compared to CE. Sixty-four women completed the P-QOL questionnaire, presenting reduced quality of life before surgery which improves postsurgically. Prolapse impact and physical, social, and role limitations correlated strongest with a low quality of life (P < 0.001).

CONCLUSION

The 1-year follow-up after mesh repair showed statistical and clinical improvement for all tools employed. dMRI seems a reliable tool for simultaneous assessment of defects in all three compartments, but tends to overestimate POP compared to clinical examination.

Positional pelvic organ prolapse (POP) evaluation using open, weight-bearing magnetic resonance imaging (MRI)

INTRODUCTION

Magnetic resonance imaging (MRI) of patients with pelvic organ prolapse (POP) is completed in the supine position. Open magnetic resonance imaging (MRO) uses vertical magnets, allowing imaging in a variety of upright postures. This pilot study used MRO to evaluate the change of prolapse in different positions compared to non-prolapsed images.

METHODS

In total, 11 women (6 POP, 5 controls) aged 24 to 65 years had 12 MRO images (midline sagittal pelvic line) consecutively when supine, sitting and standing with a full and empty bladder. Lengths between the lowest point of the bladder to the pubococcygeal (PC) and pubopromontoreal (PP) lines in each image were compared, and the ratio of bladder area under the PC and PP lines to the total bladder area.

RESULTS

Significant elongation between the PC line and lowest point of the bladder was evident in subjects with POP comparing supine and standing images (p = 0.03), but not controls (p = 0.07). Similarly, this axis was significantly longer in cystocele subjects versus controls only in the standing position. Bladder area under the PC line was significantly increased between supine and standing positions only among subjects with cystocele (p < 0.01), and significantly larger among the study group in the standing position (p < 0.005), less significant in the supine position (p = 0.015), and not significant in the sitting position (p = 0.3).

CONCLUSIONS

MRO imaging allows us to investigate the effects of upright position and weight bearing on the staging of POP. Imaging patients when sitting and standing identified that significant changes occur in the maximal descent of the bladder.

[Imaging for urinary incontinence]

BACKGROUND

Ultrasonography and functional cine magnetic resonance imaging (MRI) are noninvasive and x-ray free tools, which are currently widely used in clinical diagnostics and scientific research of male and female urinary incontinence. The increasing use and improving techniques of modern imaging tools are closely linked to rapid development of minimally invasive surgery in patients with urinary incontinence and insights gained in continence mechanisms.

METHODS

Whereas ultrasonography is a cost-efficient and readily available diagnostic tool for a routine use, the more expensive functional MRI, as a tool with more precise visualization of functional interactions and spatial representation of anatomical structures of the pelvic floor, is suitable for complex diagnostic purposes and scientific research. Both tools are already well established for evaluations of the female pelvic floor. For evaluation of the male pelvic floor, and in particular postprostatectomy incontinence, perineal ultrasonography and functional cine MRI are becoming increasingly evident.

CONCLUSION

Further development of both imaging tools will contribute to new insights into the continence mechanism and improve the techniques of radical prostatectomy and minimally invasive surgery of male and female urinary incontinence in the future.

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.

3 T MRI-based measurements for the integrity of the female pelvic floor in 25 healthy nulliparous women

AIMS

Measurements indicating a loss of integrity of the levator ani muscle, which is an integral part of the pelvic floor, have been subject of recent studies using translabial ultrasound and 3D-MRI-models. We transferred these measurements into 2D-3 T-MR-images for clinical routine, as it is objective and does not need exhaustive post-processing.

METHODS

The trial was accepted by the local ethics committee. 25 healthy volunteers fulfilled the inclusion criteria and gave written informed consent. Using high-resolution T2-weighted images (TE 5030-7810 ms, TR 88-112 ms, matrix 512, FOV 280-300 mm, ST 2-3 mm), measurements of anteroposterior hiatus (APH), laterolateral hiatus (LLH), hiatal area (HA), hiatal circumference (HC), levator area (LA), maximum muscle thickness (MMT) and levator urethra gap (LUG) were transferred from ultrasound, iliococcygeus width (IW), puborectalis attachment width (PAW), and levator symphysis gap (LSG) were transferred from 3D-MRI-models. We compared our results to previous studies in the literature.

RESULTS

Mean value was 52.22 ± 6.97 mm for APH, 33.15 ± 4 mm for LLH, 13.22 ± 3.05 cm(2) for HA, 14.19 ± 1.61 cm for HC, 7.14 ± 1.85 cm(2) for LA, 6.45 ± 2.07 mm for MMT, 19.47 ± 2.38 mm for LUG, 45 ± 3.97 mm for IW, 33.94 ± 3.34 mm for PAW, 20.54 ± 5.29 mm for LSG. Our results for APH, HA, LUG, and with limitations LA, were comparable to the literature, while HC, LLH, and MMT showed anatomical variances. Results for IW and LSG were comparable, but challenging to measure. We newly proposed a cutoff value for PAW.

CONCLUSIONS

2D-3 T-MRI combines high-resolution images with objective measurements of parameters regarding pelvic floor integrity, without resorting to exhaustive post-processing methods. Our results may provide a good foundation for further 2D-MR-studies.

Comparison of muscle fiber directions between different levator ani muscle subdivisions: in vivo MRI measurements in women

INTRODUCTION AND HYPOTHESIS

This study describes a technique to quantify muscle fascicle directions in the levator ani (LA) and tests the null hypothesis that the in vivo fascicle directions for each LA subdivision subtend the same parasagittal angle relative to a horizontal reference axis.

METHODS

Visible muscle fascicle direction in the each of the three LA muscle subdivisions, the pubovisceral (PVM; synonymous with pubococcygeal), puborectal (PRM), and iliococcygeal (ICM) muscles, as well as the external anal sphincter (EAS), were measured on 3-T sagittal MRI images in a convenience sample of 14 healthy women in whom muscle fascicles were visible. Mean ± standard deviation (SD) angle values relative to the horizontal were calculated for each muscle subdivision. Repeated measures ANOVA and post-hoc paired t tests were used to compare muscle groups.

RESULTS

Pubovisceral muscle fiber inclination was 41 ± 8.0°, PRM was -19 ± 10.1°, ICM was 33 ± 8.8°, and EAS was -43 ± 6.4°. These fascicle directions were statistically different (p < 0.001). Pairwise comparisons among levator subdivisions showed angle differences of 60° between PVM and PRM, and 52° between ICM and PRM. An 84° difference existed between PVM and EAS. The smallest angle difference between levator divisions was between PVM and ICM 8°. The difference between PRM and EAS was 24°. All pairwise comparisons were significant (p < 0.001).

CONCLUSIONS

The null hypothesis that muscle fascicle inclinations are similar in the three subdivisions of the levator ani and the external anal sphincter was rejected. The largest difference in levator subdivision inclination, 60°, was found between the PVM and PRM.

Comparison of muscle fiber directions between different levator ani muscle subdivisions: in vivo MRI measurements in women

INTRODUCTION AND HYPOTHESIS

This study describes a technique to quantify muscle fascicle directions in the levator ani (LA) and tests the null hypothesis that the in vivo fascicle directions for each LA subdivision subtend the same parasagittal angle relative to a horizontal reference axis.

METHODS

Visible muscle fascicle direction in the each of the three LA muscle subdivisions, the pubovisceral (PVM; synonymous with pubococcygeal), puborectal (PRM), and iliococcygeal (ICM) muscles, as well as the external anal sphincter (EAS), were measured on 3-T sagittal MRI images in a convenience sample of 14 healthy women in whom muscle fascicles were visible. Mean ± standard deviation (SD) angle values relative to the horizontal were calculated for each muscle subdivision. Repeated measures ANOVA and post-hoc paired t tests were used to compare muscle groups.

RESULTS

Pubovisceral muscle fiber inclination was 41 ± 8.0°, PRM was -19 ± 10.1°, ICM was 33 ± 8.8°, and EAS was -43 ± 6.4°. These fascicle directions were statistically different (p < 0.001). Pairwise comparisons among levator subdivisions showed angle differences of 60° between PVM and PRM, and 52° between ICM and PRM. An 84° difference existed between PVM and EAS. The smallest angle difference between levator divisions was between PVM and ICM 8°. The difference between PRM and EAS was 24°. All pairwise comparisons were significant (p < 0.001).

CONCLUSIONS

The null hypothesis that muscle fascicle inclinations are similar in the three subdivisions of the levator ani and the external anal sphincter was rejected. The largest difference in levator subdivision inclination, 60°, was found between the PVM and PRM.

The length of anterior vaginal wall exposed to external pressure on maximal straining MRI: relationship to urogenital hiatus diameter, and apical and bladder location

INTRODUCTION AND HYPOTHESIS

In cystoceles, the distal anterior vaginal wall (AVW) bulges out through the introitus and is no longer in contact with the posterior vaginal wall or perineal body, exposing the pressure differential between intra-abdominal pressure and atmospheric pressure. The goal of this study is to quantify the length of the exposed vaginal wall length and to investigate its relationship with other factors associated with the AVW support, such as most dependent bladder location, apical location, and hiatus diameter, demonstrating its key role in cystocele formation.

METHODS

Fifty women were selected to represent a full spectrum of AVW support. Each underwent supine, dynamic MR imaging. Most dependent bladder location and apical location were measured relative to the average normal position on the mid-sagittal plane using the Pelvic Inclination Correction System . The length of the exposed AVW and the hiatus diameter were measured as well. The relationship between exposed AVW and most dependent bladder location, apical location, and hiatus diameter were examined.

RESULTS

A bilinear relationship has been observed between exposed vaginal wall length and most dependent bladder location (R(2) = 0.91, P < 0.001). When the bladder descents up to the inflection point (about 4.4 cm away from its normal position), there is little change in the exposed AVW length. With further descent, the exposed vaginal wall length increases significantly, with a 2 cm increase in exposed AVW length for every additional 1 cm of drop bladder location. A similar but weaker bilinear relationship exists between exposed AVW and apical location. Exposed vaginal wall length is also highly correlated with hiatus diameter (R(2) = 0.85, P < 0.001).

CONCLUSION

A bilinear relationship exists between exposed vaginal wall length and most dependent bladder location and apical location. It is when the bladder descent is beyond the inflection point that exposed vaginal wall length increases significantly.

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.