MRI pelvic landmark angles in the assessment of apical pelvic organ 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.

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.

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.

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 importance of uterosacral ligament anatomy in overactive bladder: A preliminary study

Objective:

To evaluate whether uterosacral ligament (USL) thickness measured using magnetic resonance imaging (MRI) was associated with overactive bladder (OAB) in otherwise healthy women.

Materials and Methods:

The study comprised 27 women with OAB and 27 healthy women (control group) who were followed up at the Obstetrics and Gynecology Department of a tertiary referral center. All subjects were evaluated using pelvic MRI to determine the transverse USL thickness. These measurements were compared between the two groups. p values less than 0.05 were considered statistically significant.

Results:

The mean age of women in the OAB and control groups were 43.88±9.36 years and 39.92±5.36 years, respectively. The mean body mass index in the OAB group was 29.77±4.82 kg/m² and 27.49±3.44 kg/m² in the control group. In the comparison of Pelvic Organ Prolapse Quantification system stages between the groups, no statistically significant relationship was determined. In the OAB group, the mean right USL thickness was 2.04±0.34 mm, and the mean left USL was 2.04±0.52 mm. In the control group, the mean right USL thickness was 2.17±0.47 mm, and the mean left USL was 2.09±0.51 mm. There were no statistically significant differences in terms of USL thickness between the OAB and control groups (p>0.05).

Conclusion:

No previous studies have been identified in the literature that have investigated the relationship between USL thicknesses and urinary incontinence. In the present study, no significant relationship could be demonstrated between right and left USL thicknesses of the OAB and control groups. This was a preliminary study, and further research with larger sample sizes is required to reach a final conclusion.

Does bilateral sacrospinous fixation with synthetic mesh recreate nulliparous pelvic anatomy? An MRI evaluation

OBJECTIVES

The aim of this study was to determine whether the bilateral sacrospinous vault fixation (BSSVF) with synthetic, polypropylene mesh arms restores the nulliparous anatomic relationships of the vaginal vault in women with and without uterus using magnetic resonance imaging (MRI).

METHODS

This was a prospective case series of women with symptomatic pelvic organ prolapse (POP) who, after BSSVF, underwent a pelvic MRI (1-13 months postoperatively). Postsurgical pelvic distances were measured from MRI scans and compared with measurements from a group of 11 nulliparous women with adequate pelvic support who underwent MRI in a previous study. Our primary outcome measure was the difference in average distance from the vault to the ischial spine among women after BSSVF when compared with the average nulliparous distances. The secondary outcome measures were the difference in average distance from the posterior fornix to the sacrum and the change in apical POP quantification parameters 6 weeks after surgery.

RESULTS

Ten women underwent MRI post-BSSVF-4 women with and 6 women without uterine preservation. In the BSSVF group, similar to the nulliparous group measurements, the average distance between the vaginal apex and the spine was 5.2 cm (SD, 0.8) (95% confidence interval, -0.6 to 0.5; P = 0.92). There was an anterior-inferior displacement of the line between the vaginal apex and the sacrum in women who underwent BSSVF. The posterior fornix was 7.4 cm (SD, 1.2) from the second sacral vertebra versus 5.6 cm (SD, 1.5) in women without POP (P < 0.01). Adequate clinical resolution of apical prolapse was confirmed in all women 6 weeks post-BSSVF.

CONCLUSIONS

The BSSVF with synthetic mesh restores the anatomy between the vagina and the ischial spines. Clinical studies are underway to compare BSSVF with standard techniques of vaginal vault prolapse repair.

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.

Magnetic resonance imaging of abdominal versus vaginal prolapse surgery with mesh

INTRODUCTION AND HYPOTHESIS

We compared two surgical approaches in patients with symptomatic prolapse of the vaginal apex with normal controls by analyzing pelvic landmark relationships measured using magnetic resonance imaging (MRI) before and after surgery.

METHODS

In this prospective multicenter pilot study involving 16 participants, nulliparous controls (n = 6) were compared with ten parous (3.0 ± 1.0) women with uterine apical prolapse equal to or greater than stage 2. Group A (n = 5) underwent abdominal sacral colpopexy with monofilament polypropylene mesh and group B (n = 5) with vaginal mesh kit repair (Total ProLift). Subtotal hysterectomy was performed in all group A and no group B women. All patients underwent preoperative and 3-month postoperative Pelvic Organ Prolapse Quantification (POP-Q) and dynamic MRI. Comparison of MRI pelvic angles and distances was performed and analyzed by Mann-Whitney rank sum test and chi-square test.

RESULTS

Vaginal apical support is similar at 3 months for abdominal sacral colpopexy (ASCP) and ProLift by POP-Q examination and MRI analysis. In both treatment groups, the postoperative POP-Q point C and MRI parameters were similar to nulliparous controls at 3 months.

CONCLUSIONS

Anatomic outcomes for ASCP compared with ProLift were similar at 3 months in terms of vaginal apical support by POP-Q and MRI analysis. Continued comparative analysis of postoperative support with objective imaging seems warranted.