MR defecography technique: recommendations of the society of abdominal radiology's disease-focused panel on pelvic floor imaging

[Dynamic magnetic resonance imaging of the pelvic floor: clinical application]

BACKGROUND

Dynamic magnetic resonance imaging (MRI) of the pelvic floor plays a key role in imaging complex pelvic floor dysfunction. The simultaneous detection of multiple findings in a complex anatomic setting renders correct analysis and clinical interpretation challenging.

OBJECTIVES

The most important aspects (anatomy of the pelvic floor, three compartment model, morphological and functional analysis, reporting) for a successful clinical use of 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 panel of ESUR/ESGAR in 2016.

RESULTS

The pelvic floor is a complex anatomic structure, mainly formed by the levator ani muscle, the urethral support system and the endopelvic fascia. Firstly, morphological changes of these structures are analysed on the static sequences. Secondly, the functional analysis using the three compartment model is performed on the dynamic sequences during squeezing, straining and defecation. Pelvic organ mobility, pelvic organ prolapse, the anorectal angle and pelvic floor relaxation are measured and graded. The diagnosis of cystoceles, enteroceles, rectoceles, the uterovaginal as well as anorectal decent, intussusceptions and dyssynergic defecation should be reported using a structured report form.

CONCLUSIONS

A comprehensive analysis of all morphological and functional findings during dynamic MRI of the pelvic floor can provide information missed by other imaging modalities and hence alter therapeutic strategies.

[Imaging of the pelvic floor (MR defecography) : The surgeon's perspective]

BACKGROUND

Magnetic resonance defecography (MRD) plays a central role in diagnosing pelvic floor functional disorders by visualizing the entire pelvic floor along with pelvic organs and providing functional assessment of the defecation process. A shared understanding between radiology and surgery regarding indications and interpretation of findings is crucial for optimal utilization of MRD.

OBJECTIVES

This review aims to explain the indications for MRD from a surgical perspective and elucidate the significance of radiological findings for treatment. It intends to clarify for which symptoms MRD is appropriate and which criteria should be followed for standardized results. This is prerequisite to develop interdisciplinary therapeutic approaches.

MATERIALS AND METHODS

A comprehensive literature search was conducted, including current consensus guidelines.

RESULTS

MRD can provide relevant findings in the diagnosis of fecal incontinence and obstructed defecation syndrome, particularly in cases of pelvic floor descent, enterocele, intussusception, and pelvic floor dyssynergia. However, rectocele findings in MRD should be interpreted with caution in order to avoid overdiagnosis.

CONCLUSION

MRD findings should never be considered in isolation but rather in conjunction with patient history, clinical examination, and symptomatology since morphology and functional complaints may not always correlate, and there is wide variance of normal values. Interdisciplinary interpretation of MRD results involving radiology, surgery, gynecology, and urology, preferably in the context of pelvic floor conferences, is recommended.

[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.

[Radiological imaging following pelvic prolapse surgery]

CLINICAL/METHODICAL ISSUE

Pelvic organ prolapse is a common condition in women, for which both conservative and surgical interventions are available. Knowledge of the different surgical procedures and the materials used is essential for adequate radiological diagnosis after prolapse surgery in order to differentiate potential complications from normal postoperative changes.

STANDARD RADIOLOGICAL METHODS

In the immediate postoperative period, computed tomography (CT) is often the modality of choice for evaluating acute complications such as bleeding or organ injuries. Magnetic resonance imaging (MRI) provides excellent soft tissue contrast and is therefore generally preferred for assessing subacute and chronic complications.

METHODICAL INNOVATIONS

Innovative techniques such as dynamic MRI protocols can improve the radiological assessment after prolapse surgery by enabling the evaluation of organ mobility.

PERFORMANCE

Radiological standard procedures such as computed tomography (CT) and MRI provide detailed and reliable information about the postoperative site and potential complications following prolapse surgery.

ACHIEVEMENTS

Radiological imaging plays an important role in the evaluation of patients after prolapse surgery, particularly when complications are suspected. Accurate radiological diagnosis can guide further appropriate therapeutic measures.

Investigating anorectal function using postoperative MRI-based fibrosis score in patients with locally advanced rectal cancer receiving neoadjuvant chemoradiotherapy: a two-center study

PURPOSE

This study aimed to develop a postoperative MRI-based fibrosis scoring system and to assess its correlation with anorectal function in locally advanced rectal cancer (LARC) cases administered neoadjuvant chemoradiotherapy (nCRT).

METHODS

Pathologically confirmed LARC cases administered nCRT and radical resection were assessed retrospectively. Based on postoperative magnetic resonance imaging (MRI) findings, anastomotic fibrosis score (AFS) and perirectal fibrosis score (PFS) were determined to evaluate the extent of fibrosis. The Wexner continence score for anorectal function was obtained 2 years postoperatively and assessed for correlation with MRI fibrosis scores. The cases were divided into 2 groups by the median Wexner score. Univariable and multivariable analyses were adopted for building a nomogram model, whose diagnostic performance was estimated by receiver operating characteristic (ROC) and decision curve analyses (DCA).

RESULTS

Finally, 144 patients with LARC were included in cohort 1 (training set). 52 patients were enrolled in cohort 2 (external validation set). Spearman correlation analysis indicated that AFS and PFS were positively correlated with the Wexner score. Univariable and multivariable analyses revealed age, tumor height, AFS, and PFS were independent predictors of anorectal function. The nomogram model achieved a good diagnostic performance, with AUCs of 0.800 and 0.827 in the training and validation sets, respectively; its predicting value was also confirmed by DCA.

CONCLUSION

The present study showed AFS and PFS derived from postoperative MRI are positively correlated with Wexner score. In addition, the new scoring system was effective in predicting anorectal function in LARC cases administered nCRT.

Future directions in imaging pouches

The sections of this special issue on the ileal pouch demonstrate that in the nearly 45 years since the ileal pouch has been utilized to treat patients with colitis and familial adenomatous polyposis, a substantial number of patients experience both short- and long-term morbidity and that imaging plays an important role in their management. Further, referral centers are encountering an increasing number of patients with pouch and peri-pouch complications and dysfunction. Many of these patients have had their pouches for years, and many have experienced a reduced quality of life as a result of their symptoms.As we look to the future, what are the specific questions that arise from this compilation of experience from institutions that see large numbers of patients with an ileal pouch? In what areas are we deficient? In what areas are we using the wrong methods? What should we be doing differently?

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.

MRI defecography revisited. At-rest pelvic floor measurements with and without rectal gel. Is there a difference?

PURPOSE

The authors sought to test if there was a difference in key pelvic floor measurements obtained during MR defecography at-rest, i.e., H-line, M-line and anorectal angle (ARA), before and after rectal gel administration. The authors also sought to determine if any observed differences would affect the interpretation of the defecography studies.

METHODS

Institutional Review Board approval was obtained. An abdominal fellow retrospectively reviewed the images of all patients who underwent MRI defecography at our institution from January 2018 through June 2021. The H-line, M-line and ARA values were remeasured on T2-weighted sagittal images, with and without rectal gel for each patient.

RESULTS

One hundred and eleven (111) studies were included in the analysis. 18% (N = 20) of patients satisfied the criterion for pelvic floor widening before gel administration based on H-line measurement. This increased to 27% (N = 30) after rectal gel (p = 0.08). 14.4% (N = 16) met the M-line measurement criterion for pelvic floor descent before gel administration. This increased to 38.7% after rectal gel (N = 43) (p < 0.001). 67.6% (N = 75) demonstrated an abnormal ARA prior to administration of rectal gel. This decreased to 58.6% (N = 65) after rectal gel administration (p = 0.07). The overall reporting discrepancies incurred by the presence or absence of rectal gel were 16.2%, 29.7% and 23.4% for H-line, M-line and ARA, respectively.

CONCLUSION

The instillation of gel during MR defecography can cause significant changes to the observed pelvic floor measurements at-rest. This in turn can influence the interpretation of defecography studies.

Complications of Mesh Sacrocolpopexy and Rectopexy: Imaging Review

Sacrocolpopexy and rectopexy are commonly used surgical options for treatment of patients with pelvic organ and rectal prolapse, respectively. These procedures involve surgical fixation of the vaginal vault or the rectum to the sacral promontory with mesh material and can be performed independently of each other or in a combined fashion and by using an open abdominal approach or laparoscopy with or without robotic assistance. Radiologists can be particularly helpful in cases where patients' surgical histories are unclear by identifying normal sacrocolpopexy or rectopexy mesh material and any associated complications. Acute complications such as bleeding or urinary tract injury or stricture are generally evaluated with CT. More chronic complications such as mesh extrusion or exposure with or without fistulization to surrounding structures are generally evaluated with MRI. Other complications can have a variable time of onset after surgery. Patients with suspected bowel obstruction are generally evaluated with CT. Those with suspected infection, abscess formation, and discitis or osteomyelitis may be evaluated with MRI, although CT evaluation may be appropriate in certain scenarios. The authors review the sacrocolpopexy and rectopexy surgical techniques, discuss appropriate imaging protocols for evaluation of patients with suspected complications, and illustrate the normal appearance and common complications of these procedures. ^© RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Tailoring surgery for obstructed defecation syndrome to the 'iceberg diagram': Long-term results

BACKGROUND

Patients with obstructed defecation syndrome may present with a wide spectrum of disorders. The iceberg diagram, which focuses on the underlying occult diseases, has been proposed for an accurate diagnosis. The iceberg diagram deals with lesions, which, if neglected, may worsen the prognosis. The aim of this study was to evaluate the effect of using the iceberg diagram on the clinical results.

METHODS

Patients operated for obstructed defecation syndrome based on the iceberg diagram between 2008 and 2018 were evaluated pre- and postsurgery. All patients underwent psychosomatic assessment, abdominal and perineal examination, proctoscopy, vaginoscopy, transanal ultrasound, and defecography. Postoperative complications were also evaluated.

RESULTS

Of the 80 operated patients, 73 were females; median age was 47 (range 26-78) years. All had a rectal internal mucosal prolapse and 85% had a rectocele. The most frequent occult diseases were functional (mental distress [46%]) or organic (colpo-cysto-enterocele [44%]). Surgery was tailored according to the iceberg diagram with prolapsectomy and rectocele repair the most commonly used among 8 different procedures. A total of 14% of patients had a postoperative complication. Median follow-up was 72 months. Obstructed defecation syndrome score significantly decreased from 10.5 ± 4.8 (mean + standard deviation) to 3.4 ± 3.6 (P < .01) and 68% of patients reported to be either improved or cured.

CONCLUSION

The use of the iceberg diagram in obstructed defecation syndrome patients assists in identifying latent "submerged lesions' that may negatively impact the functional outcome of surgery. A clinical approach to patients with obstructed defecation syndrome tailored according to the iceberg diagram allows the identification of occult lesions and to achieve good long-term results.

Imaging Review of Gastrointestinal Motility Disorders

The motor function of the gastrointestinal tract relies on the enteric nervous system, which includes neurons spanning from the esophagus to the internal anal sphincter. Disorders of gastrointestinal motility arise as a result of disease within the affected portion of the enteric nervous system and may be caused by a wide array of underlying diseases. The etiology of motility disorders may be primary or due to secondary causes related to infection or inflammation, congenital abnormalities, metabolic disturbances, systemic illness, or medication-related side effects. The symptoms of gastrointestinal dysmotility tend to be nonspecific and may cause diagnostic difficulty. Therefore, evaluation of motility disorders requires a combination of clinical, radiologic, and endoscopic or manometric testing. Radiologic studies including fluoroscopy, CT, MRI, and nuclear scintigraphy allow exclusion of alternative pathologic conditions and serve as adjuncts to endoscopy and manometry to determine the appropriate diagnosis. Additionally, radiologist understanding of clinical evaluation of motility disorders is necessary for guiding referring clinicians and appropriately imaging patients. New developments and advances in imaging techniques have allowed improved assessment and diagnosis of motility disorders, which will continue to improve patient treatment options. Online supplemental material is available for this article. ^©RSNA, 2022.

X-ray video defaecography is superior to magnetic resonance defaecography in the imaging of defaecation disorders

AIM

The aim of this work was to study the technical success and diagnostic capability of magnetic resonance defaecography (MRD) compared with video defaecography (VD).

METHOD

Sixty four women with defaecation disorders underwent both MRD and x-ray VD over 1 year. The assessment by two radiologists in consensus was retrospective and blinded. The technical success of straining and evacuation was evaluated subjectively. The presence of enterocele, intussusception, rectocele and dyssynergic defaecation was analysed according to established criteria, with VD as the standard of reference.

RESULTS

It was found that 62/64 (96.9%) VD studies were technically fully diagnostic compared with 29/64 (45.3%) for MRD. The number of partially diagnostic studies was 1/64 (1.6%) for VD versus 21/64 (32.8%) for MRD, with 1/64 (1.6%) (VD) and 14/64 (21.9%) (MRD) being nondiagnostic. Thirty enteroceles were observed by VD compared with seven in MRD with moderate agreement (κ = 0.41). Altogether 53 intussusceptions were observed by VD compared with 27 by MRD with poor agreement (κ = -0.10 and κ = 0.02 in recto-rectal and recto-anal intussusception, respectively). Moderate agreement (κ = 0.47) was observed in diagnosing rectocele, with 47 cases by VD and 29 by MRD. Dyssynergic defaecation was observed in three patients by VD and in 11 patients by MRD, with slight agreement (κ = 0.14).

CONCLUSION

The technical success and diagnostic capabilities of VD are better than those of MRD. VD remains the method of choice in the imaging of defaecation disorders.

Inadequate Rectal Pressure and Insufficient Relaxation and Abdominopelvic Coordination in Defecatory Disorders

BACKGROUND & AIMS

Diagnostic tests for defecatory disorders (DDs) asynchronously measure anorectal pressures and evacuation and show limited agreement; thus, abdominopelvic-rectoanal coordination in normal defecation and DDs is poorly characterized. We aimed to investigate anorectal pressures, anorectal and abdominal motion, and evacuation simultaneously in healthy and constipated women.

METHODS

Abdominal wall and anorectal motion, anorectal pressures, and rectal evacuation were measured simultaneously with supine magnetic resonance defecography and anorectal manometry. Evacuators were defined as those who attained at least 25% rectal evacuation. Supervised (logistic regression and random forest algorithm) and unsupervised (k-means cluster) analyses identified abdominal and anorectal variables that predicted evacuation.

RESULTS

We evaluated 28 healthy and 26 constipated women (evacuators comprised 19 healthy participants and 8 patients). Defecation was initiated by abdominal wall expansion that was coordinated with anorectal descent, increased rectal and anal pressure, and then anal relaxation and rectal evacuation. Compared with evacuators, nonevacuators had lower anal diameters during simulated defecation, rectal pressure, anorectal junction descent, and abdominopelvic-rectoanal coordination (P < .05). Unsupervised cluster analysis identified 3 clusters that were associated with evacuator status (P < .01), that is, 10 evacuators (83%), 16 evacuators (73%), and 1 evacuator (5%) in clusters 1, 2, and 3, respectively. Each cluster had distinct characteristics (eg, maximum abdominosacral distance, rectal pressure, anorectal junction descent, anal diameter) and correlates that were more (clusters 1-2) or less (cluster 3) conducive to evacuation. Cluster 2 had 16 evacuators (73%) and intermediate characteristics (eg, lower anal resting pressure and relaxation during evacuation; P < .05).

CONCLUSIONS

Women with DDs and a modest proportion of healthy women had specific patterns of anorectal dysfunction, including inadequate rectal pressurization, anal relaxation, and abdominopelvic-rectoanal coordination. These observations may guide individualized therapy for DDs in the future.

Mini-review: Modern Concept of Pelvic Organ Prolapse

Symptomatic pelvic organ prolapse (POP) has been increasing in recent years for both developed and developing countries. By 2050, as the adult population grows, the number of women with symptomatic POP will increase by 46%. Due to the increasing number of complications after surgery among women with POP, the current understanding of treatment has become extremely important for researchers and practitioners. There are many novel conservative and surgical treatment approaches under investigation. However, some primary surgical treatments show an approximate 30–50% risk of repeated pelvic floor reconstruction. Therefore, the review aims to summarize several conservative treatment options and identify critical areas of need for future research.

Consensus Definitions and Interpretation Templates for Magnetic Resonance Imaging of Defecatory Pelvic Floor Disorders: Proceedings of the Consensus Meeting of the Pelvic Floor Disorders Consortium of the American Society of Colon and Rectal Surgeons, the Society of Abdominal Radiology, the International Continence Society, the American Urogynecologic Society, the International Urogynecological Association, and the Society of Gynecologic Surgeons

The Pelvic Floor Disorders Consortium (PFDC) is a multidisciplinary organization of colorectal surgeons, urogynecologists, urologists, gynecologists, gastroenterologists, radiologists, physiotherapists, and other advanced care practitioners. Specialists from these fields are all dedicated to the diagnosis and management of patients with pelvic floor conditions, but they approach, evaluate, and treat such patients with their own unique perspectives given the differences in their respective training. The PFDC was formed to bridge gaps and enable collaboration between these specialties. The goal of the PFDC is to develop and evaluate educational programs, create clinical guidelines and algorithms, and promote high quality of care in this unique patient population. The recommendations included in this article represent the work of the PFDC Working Group on Magnetic Resonance Imaging of Pelvic Floor Disorders (members listed alphabetically in Table 1). The objective was to generate inclusive, rather than prescriptive, guidance for all practitioners, irrespective of discipline, involved in the evaluation and treatment of patients with pelvic floor disorders.

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.

Variability in utilization and techniques of pelvic floor imaging: findings of the SAR pelvic floor dysfunction disease-focused panel

Pelvic floor disorders are common and can negatively impact quality of life. Imaging of patients with pelvic floor disorders has been extremely heterogeneous between institutions due in part to variations in clinical expectations, technical considerations, and radiologist experience. In order to assess variations in utilization and technique of pelvic floor imaging across practices, the society of abdominal radiology (SAR) disease-focused panel on pelvic floor dysfunction developed and administered an online survey to radiologists including the SAR membership. Results of the survey were compared with published recommendations for pelvic floor imaging to identify areas in need of further standardization. MRI was the most commonly reported imaging technique for pelvic floor imaging followed by fluoroscopic defecography. Ultrasound was only used by a small minority of responding radiologists. The survey responses demonstrated variability in imaging utilization, patient referral patterns, imaging protocols, patient education, and interpretation and reporting of pelvic floor imaging examinations. This survey highlighted inconsistencies in technique between institutions as well as potential gaps in knowledge that should be addressed to standardize evaluation of patients with pelvic floor dysfunction.