[Dynamic magnetic resonance imaging of the pelvic floor: Technical aspects]

BACKGROUND

Dynamic magnetic resonance imaging (MRI) of the pelvic floor plays a key role in imaging complex pelvic floor dysfunction. High-quality examination is crucial for diagnostic benefit but can be technically challenging.

OBJECTIVES

The most important technical aspects (patient selection, patient preparation, MRI technology, MRI scan protocol, success control) for obtaining a state-of-the-art dynamic MRI of the pelvic floor are summarized.

MATERIALS AND METHODS

Review of the scientific literature on dynamic pelvic MR imaging with special consideration of the joint recommendations provided by the expert panels of European Society of Urogenital Radiology/European Society of Gastrointestinal and Abdominal Radiology (ESUR/ESGAR) in 2016 and Society of Abdominal Radiology (SAR) in 2019.

RESULTS

Examination with at least 1.5 T and a surface coil after rectal instillation of ultrasound gel is clinical standard. Dynamic MRI in a closed magnet with the patient in supine position is the most widespread technique. No clinically significant pathologies of the pelvic floor are missed compared to the sitting position in an open magnet. The minimum scan protocol should encompass static, high-resolution T2-imaging (i.e., T2-TSE) in three planes and dynamic sequences with high temporal resolution in sagittal (and possibly axial) plane (i.e., steady-state or balanced steady-state free precession) during squeezing, straining and evacuation. Detailed patient instruction and practicing prior to the scan improve patients' compliance and hence diagnostic quality.

CONCLUSIONS

A technically flawless dynamic MRI of the pelvic floor according to these standards can provide information missed by other imaging modalities and hence alter therapeutic strategies.

Diagnostic performance of dynamic MR defecography in assessment of dyssynergic defecation

PURPOSE

To assess diagnostic performance of MR defecographic findings in diagnosis of dyssynergic defecation (DD).

METHODS

This retrospective study included 46 patients with chronic constipation who met the Rome IV criteria for diagnosis of present or absent DD and underwent MRI between Jan 2015 and June 2020. Patients were divided into DD group (n = 24) and non-DD group (n = 22). Nine parameters were analyzed by two radiologists: anorectal angle (ARA) and M line at rest, defecation, and change between 2 phases; anal canal width; prominent puborectalis muscle; abnormal evacuation. Receiver operating characteristic (ROC) curves were plotted to extract the optimal cut-offs and area under the curve (AUC). Multivariate analysis was performed.

RESULTS

Seven findings showed statistically significant difference between DD and non-DD groups. M line at defecation had highest odds ratio, followed by ARA change, ARA at defecation, M line change, prominent puborectalis muscle, abnormal evacuation and anal canal width, respectively. ARA change and prominent puborectalis muscle had highest specificity (95.5% and 100%, respectively). The optimal cut-offs of ARA at defecation, ARA change, M line at defecation, M line change and anal canal width were 122°, 1.5°, 3.25 cm, 1.9 cm and 8.5 mm, respectively. Multivariate logistic regression revealed two significant findings in differentiating between DD and non-DD, including M line at defecation (OR 23.31, 95% CI 3.10-175.32) and ARA at defecation (OR 13.63, 95% CI 1.94-95.53) with sensitivity, specificity, PPV, NPV and AUC of 79.2%, 95.5%, 95%, 80.8% and 0.87(95% CI 0.78-0.97), respectively.

CONCLUSION

MR defecography has high diagnostic performance in diagnosis of DD. Although M line and ARA at defecation are two significant findings on multivariate analysis, ARA change less than 1.5 degrees and prominent puborectalis muscle have good specificity in DD diagnosis.

Dynamic ileal pouch emptying studies

Although much radiologic literature has focused on the short-term post-operative complications associated with ileal pouches, as the number of patients with long-term pouches has grown, there is increasing realization of the functional deficits that may occur long after pouch creation. Dynamic pouch imaging using fluoroscopy and MRI can provide assessment of the underlying causes of symptomatic pouch dysfunction and can provide critical insight to the management of this complex patient population. In this paper, we provide an overview of the unique problems encountered in patients with long-term ileal pouches, and provide an overview of the techniques, interpretation, and reporting for fluoroscopic and MR pouch defecography.

Defining normal pouch function in patients with ileal pouch-anal anastomosis: a pilot study

BACKGROUND

Most patients experience good functional outcomes following ileal pouch-anal anastomosis (IPAA) for ulcerative colitis.

AIM

We aimed to determine if asymptomatic patients with an IPAA had findings consistent with normal defecation on standard objective anorectal tests.

METHODS

Patients 18-65 years old with IPAA and self-reported healthy pouch function were recruited. Patients with chronic pouchitis, Crohn's disease, anastomotic stricture, or indication for IPAA other than ulcerative or indeterminate colitis were excluded. Patients underwent an interview with an abbreviated Rome Questionnaire followed by high-resolution ano-pouch manometry, balloon expulsion test, pouch barostat, and magnetic resonance (MR) defecography.

RESULTS

Twenty patients completed all testing. Six patients were excluded from the final analysis due to symptoms suggestive of pouch evacuation disorder on the abbreviated Rome Questionnaire (n = 2), structural abnormality on MR imaging (n = 3), or both (n = 1). Of the remaining 14 patients, mean anal resting pressure during high-resolution manometry was 72 ± 16 mmHg, mean anal squeeze pressure was 247 ± 69 mmHg, and mean pouch-anal gradient during the simulated evacuation was -27 ± 37 mmHg. The meantime to balloon expulsion was 54 seconds. During dynamic MR defecography, the mean descent of ano-pouch junction was 2.6 cm, and mean pouch evacuation was 44.5% and 74.2% pre- and posttoilet phase, respectively.

CONCLUSIONS

A substantial proportion of patients with IPAA and self-reported healthy pouch function have anatomic and/or functional abnormalities of the pouch. In asymptomatic IPAA patients with an anatomically normal pouch, we have proposed normal parameters for high-resolution ano-pouch manometry, time to balloon expulsion, pouch barostat, and MR defecography.

A new dıagnostic tool for assessment of pelvıc dysfunction ın MR defecography

BACKGROUND

  Pelvic floor dysfunction is characterized by incomplete fecal defecation, affecting quality of life in a negative way. Magnetic resonance defecography (MRD) is a useful examination that is ionizing radiation-free and easily reproducible, and which provides anatomical and functional details that are obtainable through multiplanar and dynamic examinations. We aimed to detect pathology using MRD in patients with suspected pelvic floor dysfunction and determine its cause.

METHODS

 MRD was performed in 79 individuals. Dynamic images were obtained at rest, straining, and during defecation. Pelvic hiatus mediolateral diameters were compared between groups.

RESULTS

  Defecation phase provided significantly more accurate results than the straining phase for determining the existence and severity of pathology. Conclusıons: The defecation phase is the most accurate phase for identifying the existence and severity of pathology. As the pelvic hiatus mediolateral diameter is thought to be an important factor in triggering pelvic dysfunction.

MR defecography review

Pelvic floor dysfunction is a relatively common but often complex condition, presenting with a variety of clinical symptoms, especially when it involves multiple compartments. Clinical exam alone is often inadequate and requires a complementary imaging study. Magnetic resonance defecography (MRD) is an excellent noninvasive diagnostic study with its multiplanar capability, lack of ionizing radiation and excellent soft tissue resolution. It can identify both anatomic and functional abnormalities in the pelvic floor and specifically excels in its ability to simultaneously detect multicompartmental pathology and help with vital pre-operative assessment. This manuscript reviews the relevant anatomical landmarks, describes the optimal technique, highlights an approach to the interpretation of MRD, and provides an overview of the various pelvic floor disorders in the different anatomical compartments.

Anterior enterocele as an etiology for anterior vaginal wall prolapse: a magnetic resonance defecography case series

Pelvic floor hernias from the posterior cul-de-sac most often contain small bowel and are called enteroceles, however may contain sigmoid colon (sigmoidocele) or only peritoneal fat (peritoneocele). These cul-de-sac hernias typically cause bulging of the posterior vaginal wall, while anterior vaginal wall bulges are typically secondary to bladder prolapse in patients with pelvic floor deficiency. We report a series of seven patients who presented with anterior vaginal wall "mass" or bulge after cystectomy and were found on magnetic resonance defecography (MRD) to have enteroceles or sigmoidoceles in the anterior rather than posterior compartment. MRD was instrumental for diagnoses in these patients and to exclude local recurrence of bladder malignancy. We also report five additional patients that were found to have bowel herniation anterior to the vaginal apex, but without history of cystectomy.

Defecation versus pre- and post-defecation Valsalva maneuvers for dynamic MR assessment of pelvic floor dysfunction

PURPOSE

To compare prevalence and severity of multi-compartment pelvic floor dysfunction between supine magnetic resonance defecography with defecation (MRD) and supine dynamic MRI during Valsalva, both with and without rectal distention.

METHODS

This was an IRB-approved, HIPAA-compliant retrospective review of consecutive patients referred for MR Defecography. MRD protocol included imaging at rest, during pre-defecation Valsalva (Pre-DV), defecation (Def), and post-defecation Valsalva (Post-DV). The Post-DV images were performed after complete evacuation either during the defecation acquisition or, in cases where patient was unable to defecate during the examination, in a conventional toilet. Size of cystocele, vaginal prolapse, anorectal (AR) descent, and enterocele were measured on all acquisitions relative to the pubococcygeal line. Rectocele size was recorded in anteroposterior dimension. The presence or absence of rectal intussusception (RI) was documented. The prevalence, absolute size, and grades of prolapse, rectocele, and RI were compared between the acquisitions using pair-wise ANOVA, Friedman, Dunn pair-wise, and Cochran-Mantel-Haenszel tests.

RESULTS

30 patients were included in the final analysis. Higher prevalence of cystocele, vaginal prolapse, enterocele, AR descent grade 2 or higher, rectocele grade 2 or higher, and RI were seen on Def compared to Post-DV and Pre-DV. Cystocele, vaginal prolapse, enterocele, AR descent, and rectocele sizes were significantly larger on Def compared to Post-DV by 0.7-1.95 cm (p ≤ 0.007). Prolapse in all compartments and rectocele size were significantly larger on Def compared to Pre-DV (p < 0.0001). Cystocele, vaginal prolapse, and enterocele sizes were significantly larger on Post-DV compared to Pre-DV (p < 0.0001). There were significant differences in grading of all types of prolapse and rectocele between the various acquisitions of MRD (p < 0.0001). Cystocele, AR descent, and rectocele grades were significantly higher on Def compared to Post-DV (p range ≤ 0.0002). Grading of all types of prolapse and rectocele was significantly higher on Def compared to Pre-DV (p < 0.0001). Cystocele, vaginal prolapse, and enterocele grades were all significantly higher on Post-DV compared to Pre-DV (p  ≤ 0.0007).

CONCLUSION

Defecation images during supine MRD elicit higher prevalence and size of prolapse of all pelvic compartments in comparison to both pre- and post-defecation Valsalva images. Post-defecation Valsalva images show larger size of anterior and middle compartment prolapse than pre-defecation Valsalva images. Functional evaluation of pelvic floor dysfunction with MRI should include image acquisition during defecation. If Valsalva images are acquired, these should be performed after the defecation acquisition and without rectal distention.

Multimodality imaging of pelvic floor anatomy

The pelvic floor is composed of a network of muscles, ligaments, and fasciae, which provide active and passive support for the pelvic organs. Impairment of these pelvic floor elements can result in a variety of functional abnormalities and single or multicompartment organ prolapse. Knowledge of normal pelvic floor anatomy can aid the radiologist in understanding the complex nature of pelvic floor dysfunction and is important for comprehensive image interpretation. This article provides an overview of normal anatomy of the pelvic floor as seen on magnetic resonance imaging, ultrasound, and fluoroscopic studies performed in the evaluation of pelvic floor function.

Statistical shape modeling of the pelvic floor to evaluate women with obstructed defecation symptoms

Obstructed defecation (OD) is common and may be related to compromised pelvic floor integrity. Magnetic resonance (MR) defecography and statistical shape modeling were used to define pelvic floor shape variations, hypothesizing that State (rest vs peak evacuation) and Group (control vs case) would significantly influence shape. 16 women underwent MR defecography (9 cases vs 7 controls). Midsagittal, 2D pelvic floors were segmented and aligned by corresponding points. Principal component scores were compared using a Two-Way Mixed MANOVA. Three modes described differences between State (p < 0.001) and Group (p = 0.023). The pelvic floor shape differed significantly between women with and without OD and during evacuation.

Advances in MR Imaging of the Female Pelvis

This article focuses on advanced MR imaging techniques of the female pelvis and clinical applications for benign and malignant disease. General and abbreviated protocols for female pelvic MR imaging are reviewed. Diffusion-weighted imaging, dynamic contrast-enhanced MR imaging, and susceptibility-weighted imaging are discussed in the context of adnexal mass characterization using the ADNEx-MR scoring system, evaluation of endometriosis, local staging of cervical and endometrial cancers, assessment of nodal and peritoneal metastasis, and potential detection of leiomyosarcoma. MR defecography is also discussed regarding evaluation of multicompartmental pelvic floor disorders.

How to define pathologic pelvic floor descent in MR defecography during defecation?

OBJECTIVES

To assess the extents of pelvic floor descent both during the maximal straining phase and the defecation phase in healthy volunteers and in patients with pelvic floor disorders, studied with MR defecography (MRD), and to define specific threshold values for pelvic floor descent during the defecation phase.

MATERIAL AND METHODS

Twenty-two patients (mean age 51 ± 19.4) with obstructed defecation and 20 healthy volunteers (mean age 33.4 ± 11.5) underwent 3.0T MRD in supine position using midsagittal T2-weighted images. Two radiologists performed measurements in reference to PCL-lines in straining and during defecation. In order to identify cutoff values of pelvic floor measurements for diagnosis of pathologic pelvic floor descent [anterior, middle, and posterior compartments (AC, MC, PC)], receiver-operating characteristic (ROC) curves were plotted.

RESULTS

Pelvic floor descent of all three compartments was significantly larger during defecation than at straining in patients and healthy volunteers (p < 0.002). When grading pelvic floor descent in the straining phase, only two healthy volunteers showed moderate PC descent (10%), which is considered pathologic. However, when applying the grading system during defecation, PC descent was overestimated with 50% of the healthy volunteers (10 of 20) showing moderate PC descent. The AUC for PC measurements during defecation was 0.77 (p = 0.003) and suggests a cutoff value of 45 mm below the PCL to identify patients with pathologic PC descent. With the adapted cutoff, only 15% of healthy volunteers show pathologic PC descent during defecation.

CONCLUSION

MRD measurements during straining and defecation can be used to differentiate patients with pelvic floor dysfunction from healthy volunteers. However, different cutoff values should be used during straining and during defecation to define normal or pathologic PC descent.

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.

The usefulness of MR defecography in the evaluation of pelvic floor dysfunction: our experience using 3T MRI

PURPOSE

To assess the usefulness of MR defecography in evaluating pelvic floor dysfunction, and to correlate several pelvic organ abnormalities with each other and with patients' symptoms and characteristics.

METHODS

MR defecographic examinations performed in 3T MRI machine of 95 patients (70 females, 25 males; mean age 48) were retrospectively reviewed. Pelvic organ abnormalities from all three compartments were recorded, including the anorectal junction descent, anterior rectocele, and cystocele. These were graded according to the known HMO system in relation to the pubococcygeal line. The correlation between these different abnormalities and their relation to patient symptoms and characteristics were evaluated.

RESULTS

Anorectal junction descent and anterior rectocele were most commonly observed, predominantly manifesting in female patients. Both were associated with abnormalities from all compartments. The middle compartment was the least affected, and its abnormality of uterine/vaginal descent tended to occur in association with the anterior compartment abnormality (cystocele). Anismus was low in incidence, and was not associated with other compartments abnormalities. Both enterocele/peritoneocele and intussusception were uncommon.

CONCLUSION

MR defecography is the modality of choice in assessing pelvic floor dysfunction, because it can neatly show various pelvic organ abnormalities from all compartments in a dynamic fashion, which are frequently coexistent. It can even show clinically silent or unsuspected abnormalities which can impact the management of patients.

Diagnostic Evaluation of Chronic Pelvic Pain

Chronic pelvic pain can result from various intra- and extra-pelvic etiologies. Although patient history and physical examination may narrow the differential diagnosis, frequently, the different etiologies have overlapping presentations. Imaging examinations such as US and/or MR imaging may help delineate the cause of pain, particularly when related to intra-pelvic organs, pelvic floor dysfunction or prolapse, synthetic material such as pelvic mesh or slings, and in some cases of neuropathic pain. Etiologies of neuropathic pain can also be assessed with non-imaging tests such as nerve conduction studies, electromyography, and testing of sacral reflexes.

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.

Magnetic resonance imaging of pelvic floor dysfunction

Pelvic floor dysfunction is largely a complex problem of multiparous and postmenopausal women and is associated with pelvic floor or organ descent. Physical examination can underestimate the extent of the dysfunction and misdiagnose the disorders. Functional magnetic resonance (MR) imaging is emerging as a promising tool to evaluate the dynamics of the pelvic floor and use for surgical triage and operative planning. This article reviews the anatomy and pathology of pelvic floor dysfunction, typical imaging findings, and the current role of functional MR imaging.