MRI comparative study of levator ani muscle changes in nulliparous and multiparous females

Background

Pelvic floor dysfunction is known to be among the principal factors influencing public health, regarding frequency, cost and effect on women’s quality of life. Radiographic assessment of the pelvic floor function and anatomy plays a vital role in the recognition of pelvic floor defects. The aim of this study is to detect the postpartum-related levator ani muscle changes thus defining the relationship between the vaginal deliveries and the etiology of pelvic floor dysfunction in order to provide guidelines to decrease the incidence of pelvic floor injuries during parturition and guide the treatment plan.

Results

There was a significant difference in the puborectalis muscle thickness between the case and control groups in the right puborectalis (P value ≤ 0.001) and in the left puborectalis (P value (≤ 0.001) as well as significant midpoint thickness (P value = 0.03) with 46.2% puborectalis muscle injury in the case group compared with none in the control group.

Conclusion

Pelvic floor MRI is highly recommended as it is a contrast-free modality that allows for both anatomical and functional analysis. Its incorporation in the routine postpartum assessment will allow early detection of abnormalities even in asymptomatic cases thus ensuring proper management and preventing the development of pelvic floor dysfunction predisposed to by repeated vaginal deliveries.

MRI of the Male Pelvic Floor

The pelvic floor is a complex structure that supports the pelvic organs and provides resting tone and voluntary control of the urethral and anal sphincters. Dysfunction of or injury to the pelvic floor can lead to gastrointestinal, urinary, and sexual dysfunction. The prevalence of pelvic floor disorders is much lower in men than in women, and because of this, the majority of the published literature pertaining to MRI of the pelvic floor is oriented toward evaluation of the female pelvic floor. The male pelvic floor has sex-specific differences in anatomy and pathophysiologic disorders. Despite these differences, static and dynamic MRI features of these disorders, specifically gastrointestinal disorders, are similar in both sexes. MRI and MR defecography can be used to evaluate anorectal disorders related to the pelvic floor. MRI can also be used after prostatectomy to help predict the risk of postsurgical incontinence, to evaluate postsurgical function by using dynamic voiding MR cystourethrography, and subsequently, to assess causes of incontinence treatment failure. Increased tone of the pelvic musculature in men secondary to chronic pain can lead to sexual dysfunction. This article reviews normal male pelvic floor anatomy and how it differs from the female pelvis; MRI techniques for imaging the male pelvis; and urinary, gastrointestinal, and sexual conditions related to abnormalities of pelvic floor structures in men.Online supplemental material is available for this article.^©RSNA, 2019.

Quantitative evaluation of age-related changes to pelvic floor muscles in magnetic resonance images from 369 patients

AIM

This study aimed to establish and validate a quantitative evaluation method for pelvic floor muscles using magnetic resonance images (MRI) and to examine the morphological change of pelvic floor muscles with aging.

METHODS

Data from 369 consecutive patients (163 men, 206 women; median age 58 years; range 17-92 years) who underwent coronal T2-weighted pelvic MRI at Osaka General Hospital between January 2016 and December 2016 were retrospectively examined. MRI of the levator ani muscle was evaluated. The MRI image blinded the patient information and was evaluated by a radiology specialist with 22 years of experience. In coronal T2-weighted MRI of the pelvis, the levator ani muscle was evaluated using the slice; it showed the most upward and downward convexity. We measured the thickness of the levator ani muscle, and the distance at the most convex part from a straight line connecting the origin and insertion of the levator ani muscle on both the left and right sides. Upward and downward convexity was recorded in positive and negative values, respectively.

RESULTS

The levator ani muscle was able to be evaluated quantitatively in all cases. Both men and women showed thinning (men: mean 3.316 mm, r = -0.388, P < 0.0001; women: mean 3.947 mm, r = -0.359, P < 0.0001) and concavity (men: mean 1.412 mm, r = -0.362, P < 0.0001; women: mean 4.979 mm, r = -0.630, P < 0.0001) of the levator ani muscle with aging.

CONCLUSIONS

A quantitative evaluation method for pelvic floor muscles using MRI was established. Aging was associated with morphological changes in the pelvic floor muscles in both men and women. Geriatr Gerontol Int 2019; 19: 834-837.

Multimodal imaging assessment and histologic correlation of the female rat pelvic floor muscles' anatomy

Pelvic floor disorders negatively impact millions of women worldwide. Although there is a strong epidemiological association with childbirth, the mechanisms leading to the dysfunction of the integral constituents of the female pelvic floor, including pelvic floor skeletal muscles, are not well understood. This is in part due to the constraints associated with directly probing these muscles, which are located deep in the pelvis. Thus, experimental models and non-invasive techniques are essential for advancing knowledge of various phenotypes of pelvic floor muscle injury and pathogenesis of muscle dysfunction, as well as developing minimally invasive approaches for the delivery of novel therapeutics. The most widely used animal model for pelvic floor disorders is the rat. However, the radiological anatomy of rat pelvic floor muscles has not been described. To remedy this gap, the current study provides the first detailed description of the female rat pelvic floor muscles' radiological appearance on MR and ultrasound images, validated by correlation with gross anatomy and histology. We also demonstrate that ultrasound guidance can be used to target rat pelvic floor muscles for possible interventional therapies.

Dynamic magnetic resonance imaging of the female pelvic floor-a pictorial review

Pelvic floor dysfunctions represent a range of functional disorders that frequently occur in adult women, carrying a significant burden on the quality of life, and its incidence tends to increase attending to the expected aging of the population. Pelvic floor dysfunctions can manifest as incontinence, constipation, and prolapsed pelvic organs. Since pelvic floor weakness is frequently generalized and clinically underdiagnosed, imaging evaluation is of major importance, especially prior to surgical correction. Given some interobserver variability of soft-tissue measurements, MR defecography allows a noninvasive, radiation-free, multiplanar dynamic evaluation of the three pelvic compartments simultaneously and with high spatial and temporal resolution. Both static/anatomic and dynamic/functional findings are important, since pelvic disorders can manifest as whole pelvic floor weakness/dysfunction or as an isolated or single compartment disorder. Imaging has a preponderant role in accessing pelvic floor disorders, and dynamic MR defecography presents as a reliable option, being able to evaluate the entire pelvic floor for optimal patient management before surgery. The purpose of this article is to address the female pelvic anatomy and explain the appropriate MR Defecography protocol, along with all the anatomic points, lines, angles, and measurements needed for a correct interpretation, to later focus on the different disorders of the female pelvic floor, illustrated with MR defecography images, highlighting the role of this technique in accessing these pathologic conditions.

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.

Translabial US and Dynamic MR Imaging of the Pelvic Floor: Normal Anatomy and Dysfunction

Pelvic floor dysfunction (PFD) is a common condition that typically affects women older than 50 years and decreases the quality of life. Weakening of support structures can involve all three pelvic compartments and cause a combination of symptoms, including constipation, urinary and fecal incontinence, obstructed defecation, pelvic pain, perineal bulging, and sexual dysfunction. The causes of PFD are complex and multifactorial; however, vaginal delivery is considered a major predisposing factor. Physical examination alone is limited in the evaluation of PFD; it frequently leads to an underestimation of the involved compartments. Imaging has an important role in the clinical evaluation, yielding invaluable information for patient counseling and surgical planning. Three- and four-dimensional translabial ultrasonography (US) is a relatively new imaging modality with high accuracy in the evaluation of PFD such as urinary incontinence, pelvic organ prolapse, and puborectalis avulsion. Evaluation of mesh implants is another important indication for this modality. Dynamic magnetic resonance (MR) imaging of the pelvic floor is a well-established modality for pelvic floor evaluation, with high-resolution images yielding detailed anatomic information and dynamic sequences yielding functional data. Specific protocols and dedicated image interpretation are required with both of these imaging methods. In this article, the authors review the normal anatomy of the female pelvic floor by using a practical approach, discuss the roles of translabial US and MR imaging in the investigation of PFD, describe the most appropriate imaging protocols, and illustrate the most common imaging findings of PFD in the anterior, middle, and posterior compartments of the pelvis. Online supplemental material is available for this article. ^©RSNA, 2018.

Pelvic MRI: Is Endovaginal or Rectal Filling Needed?

Magnetic resonance imaging is the optimal modality for pelvic imaging. It is based on T2-weighted magnetic resonance (MR) sequences allowing uterine and vaginal cavity assessment as well as rectal evaluation. Anatomical depiction of these structures may benefit from distension, and conditions either developing inside the lumen of cavities or coming from the outside may then be better delineated and localized. The need for distension, either rectal or vaginal, and the way to conduct it are matters of debate, depending on indication for which the MR examination is being conducted. In this review, we discuss advantages and potential drawbacks of this technique, based on literature and our experience, in the evaluation of various gynecological and rectal diseases.

Practical guide to dynamic pelvic floor MRI

Pelvic floor dysfunction encompasses a spectrum of functional disorders that result from impairment of the ligaments, fasciae, and muscles supporting the pelvic organs. It is a prevalent disorder that carries a lifetime risk over 10% for undergoing a surgical repair. Pelvic floor weakness presents as a wide range of symptoms, including pain, pelvic pressure or bulging, urinary and fecal incontinence, constipation, and sexual dysfunction. A correct diagnosis by clinical examination alone can be challenging, particularly in cases involving multiple compartments. Magnetic resonance imaging (MRI) allows noninvasive, radiation-free, high soft-tissue resolution evaluation of all three pelvic compartments, and has proved a reliable technique for accurate diagnosis of pelvic floor dysfunction. MR defecography with steady-state sequences allows detailed anatomic and functional evaluation of the pelvic floor. This article provides an overview of normal anatomy and function of the pelvic floor and discusses a practical approach to the evaluation of imaging findings of pelvic floor relaxation, pelvic organ prolapse, fecal incontinence, and obstructed defecation.

LEVEL OF EVIDENCE

5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1155-1170.

Vaginal delivery-related changes in the pelvic organ position and vaginal cross-sectional area in the general population

PURPOSE

Evaluate the effect of vaginal delivery on pelvic organ positions and vaginal cross-sectional areas.

METHODS

MRI of 119 premenopausal women were grouped according to the number of deliveries. The distances from the three 3-reference points (bladder, uterus, and rectum) to two 2-lines (pubococcygeal-line (PCL) and midpubic-line (MPL)), length of H- and M-lines and vaginal cross-sectional area were compared between the groups.

RESULTS

With increasing parity, distance from the rectum to PCL tended to increase (nullipara vs. bipara; p<0.01). Vaginal cross-sectional area was larger in bipara and tripara than in nullipara (p<0.01).

CONCLUSIONS

Rectal position is more caudally located and vaginal cross-sectional area is larger in bipara than in nullipara.