Morphology and dynamics of the male pelvic floor before and after retrourethral transobturator sling placement: first insight using MRI

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.

Mechanism of Action of the Transobturator Sling for Post-Radical Prostatectomy Incontinence: A Multi-institutional Prospective Study Using Dynamic Magnetic Resonance Imaging

OBJECTIVE

To compare the length of the membranous (functional) urethra in male patients who underwent the male transobturator sling (TOS) for postradical prostatectomy urinary incontinence (PPI). The TOS is in established use for treatment of PPI; however, the precise mechanism of action is unknown.

MATERIALS AND METHODS

This is a prospective case-controlled study on men undergoing male TOS surgery from 2008 to 2014. The comparison arm included patients without incontinence after radical prostatectomy. All participants underwent dynamic magnetic resonance imaging (MRI) at baseline and this was repeated after TOS placement for those who underwent the procedure. Three standardized points were measured using MRI and compared in both groups in addition to clinical measures.

RESULTS

Thirty-nine patients were enrolled and 31 patients completed the protocols. The controls (N = 14) had a longer vesicourethral anastomosis to urethra measured at the penile bulb (functional urethral length) distance compared to the pre-TOS group at rest (1.92 cm controls vs 1.27 cm pre-TOS, P = .0018) and at Valsalva (2.13 cm controls vs 1.72 cm pre-TOS, P = .0371). Placement of the sling (N = 17) increased the functional urethral length distance at rest (1.92 cm control vs 1.53 cm post-TOS, P = .09) and at Valsalva (1.94 cm post-TOS vs 2.13 cm control, P = .61), so that the difference was no longer statistically significant.

CONCLUSION

We identified that one possible mechanism in improvement in stress urinary incontinence post-TOS placement is the lengthening of the vesicourethral anastomosis to bulbar-urethra distance. This is the first such study utilizing dynamics MRI in post prostatectomy controls, incontinent pre-TOS, and post-TOS to assess and show these findings.

[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.

[Diagnosis and surgical treatment of postprostatectomy stress incontinence: recommendation of the working group Urologische Funktionsdiagnostik und Urologie der Frau]

Today, for the surgical treatment of postprostatectomy incontinence, several treatment options are available, e.g., adjustable and functional sling systems, artificial sphincter, bulking agents, and balloons. However, no recommendations in terms of specific diagnostic tools and differentiated treatment options for everyday life are available. Our aim is to provide some clinically relevant recommendations for the necessary diagnostic workup and different treatment options of postprostatetectomy incontinence to support clinical decisions in everyday life. Treatment selection should be based on contraindications. However, there is a broad overlap of the various surgical options.

Slings in the management of male stress urinary incontinence

PURPOSE OF REVIEW

The use of synthetic slings for the treatment of male stress urinary incontinence (SUI) has increased over the last decade. Several sling designs and techniques are now available. The purpose of this review is to summarize the past literature with a focus on more recent contributions.

RECENT FINDINGS

The recent literature focusses on the retrourethral transobturator sling (RTS), which is considered noncompressive. MRI of patients undergoing RTS has shown an increase in membranous urethral length and elevation of the external urethral sphincter, whereas a recent large series demonstrated approximately a half and a quarter of patients are cured or improved, respectively, at 1 year after RTS implantation, with results sustained through to 3 years. Serious complications such as urethral erosion occur rarely.

SUMMARY

The available evidence suggests that male slings can be an efficacious and well tolerated treatment modality for men with SUI. Nevertheless, important questions remain with regard to the durability of repair, device safety and comparative efficacy. The mechanism of action and factors that predict failure remain to be fully elucidated.

Could the sling position influence the clinical outcome in male patients treated for urinary incontinence? A magnetic resonance imaging study with a 3 tesla system

OBJECTIVE

To analyze the morphologic changes visible on magnetic resonance imaging (MRI) after sling procedure in continent patients and to compare MRI findings with the incontinent ones, to detect possible factors explaining the different clinical outcomes.

METHODS

Twenty-seven male patients who were treated with Advance sling for urinary stress incontinence after prostate surgery were enrolled: 16 had clinical recovery, whereas 11 had persistent incontinence. Patients after sling were defined as continent if used 0-1 dry "security pad" or incontinent >1 pad. Magnetic Resonance examinations were performed with a 3 Tesla system and included 3-dimensional T2-weighted sequence. Three readers performed a qualitative (representation of the bulb and indentation of the sling) and a quantitative analysis (length of the bulb posterior to the sling and distance of the sling from a line bisecting the pubic symphysis).

RESULTS

The sling was clearly recognizable in all 16 continent patients but only in 2 of 11 incontinent ones. The length of the bulb posterior to the sling was >10 mm (range, 10-28) in all continent patients and in 2 of the incontinent ones. The sling was coincident with a line drawn through the long axis of the pubic bone in 9 of 16 continent patients. A statistically significant association was found between MRI qualitative findings and continence status (P <.0001).

CONCLUSION

On the basis of our MRI results, the position of the sling and, in particular, the length of the urethral bulb posterior to the sling seem to be correlated with continence and must be considered in case of treatment failure.

[Diagnosis of urinary stress incontinence in men]

Male lower urinary tract symptoms (LUTS) occur more frequently with increasing age. LUTS can either be caused by benign prostatic syndrome (BPS) and consecutive subvesical obstruction as well as detrusor hyperactivity. On the other hand, stress urinary incontinence is mostly seen after surgical intervention in the pelvis like radical prostatectomy. Also high volume centers report persisting incontinence rates of 2-4 % after radical prostatectomy.The diagnostic procedure in men with LUTS is divided in two steps: basic diagnostics, followed by a conservative treatment option, and extended diagnostic procedures including measurement of bladder pressure during filling and voiding. In addition, radiologic examinations, including voiding cystouretherogram, retrograde cystogram, CT scan, MRI scan, are added according to the severity of the symptoms and the scheduled surgical procedure. According to the guidelines of the DGU, EAU, AUA, and ICS, this extended examination is also mandatory prior to any surgical procedure like suburethral tapes, artificial sphincters, and sacral foramen neuronal stimulators.

Is a wider angle of the membranous urethra associated with incontinence after radical prostatectomy?

PURPOSE

To investigate whether differences in the anatomy and dynamics of the pelvic floor (PF) in patients after radical prostatectomy (RP) depicted on magnetic resonance imaging (MRI) are associated with continence status.

METHODS

In the prospective designed study, 24 patients with post-prostatectomy stress urinary incontinence were enrolled. Additionally, 10 continent patients after RP were matched for age, body mass index and perioperative parameters. All patients underwent continence assessment and MRI (TrueFISP sequence; TR 4.57 ms; TE 2.29 ms; slice thickness 7 mm; FOV 270 mm) 12 months after RP. Images were analyzed for membranous urethra length (MUL), angle of the membranous urethra (AMU), severity of periurethral/urethral fibrosis, lifting of the levator ani muscle, lowering of the posterior bladder wall (BPW), bladder neck (BN) and external urinary sphincter (EUS), and symphyseal rotation of these structures during the Valsalva maneuver and voiding.

RESULTS

Compared to continent controls, incontinent patients showed a significant wider AMU during voiding (p = 0.002) and more pronounced lowering of the BN and EUS (p < 0.001). No differences between the groups were found in symphyseal rotation of the analyzed structures, MUL and severity of periurethral/urethral fibrosis.

CONCLUSIONS

The angle of the membranous urethra as a result of anchoring of the BN and EUS in the PF appears to be an important functional factor with an essential impact on continence after RP. Functional MRI seems to be a helpful imaging tool for morphologic and dynamic evaluation of the PF.

MRI findings of radiation-induced changes in the urethra and periurethral tissues after treatment for prostate cancer

PURPOSE

To assess radiotherapy (RT)-induced changes in the urethra and periurethral tissues after treatment for prostate cancer (PCa).

METHODS AND MATERIALS

This retrospective study included 108 men (median age, 64 years; range, 43-87 years) who received external-beam radiotherapy (EBRT) and/or brachytherapy for PCa and underwent endorectal-coil MRI of the prostate within 180 days before RT and a median of 20 months (range, 2-62 months) after RT. On all MRIs, two readers independently measured the urethral length (UL) and graded the margin definition (MD) of the urethral wall and the signal intensities (SIs) of the urethral wall and pelvic muscles on 4-point scales.

RESULTS

The mean urethral length decreased significantly from pre- to post-RT MRI (from 15.2 to 12.6mm and from 14.4 to 12.9 mm for readers 1 and 2, respectively; both p-values <0.0001). Brachytherapy resulted in greater urethral shortening than EBRT. After RT, SI in the urethral wall increased in 57% (62/108) and 35% (38/108) of patients (readers 1 and 2, respectively). The frequency and magnitude of SI increase in pelvic muscles depended on muscle location. In the obturator internus muscle, SI increased more often after EBRT than after brachytherapy, while in the periurethral levator ani muscle SI increased more often after brachytherapy than after EBRT.

CONCLUSION

After RT for PCa, MRI shows urethral shortening and increased SI of the urethral wall and pelvic muscles in substantial percentages of patients.

Pelvic floor musculature and bladder neck changes before and after continence recovery after radical prostatectomy in pelvic MRI

PURPOSE

To evaluate the changes in pelvic floor anatomy using MRI before and after continence recovery after radical prostatectomy (RP).

MATERIALS AND METHODS

Thirteen men with prostate cancer who underwent RP (mean age, 67.4 ± 8.8 years) volunteered for this study. Prostate MRIs were performed during the preoperative (i), incontinent (ii), and continent (iii) periods. The membranous urethra length (MUL), puborectalis muscle (PRM) thickness, and the position of the bladder neck in relation to the pubic bone (Dx) and the pubococcygeous line (Dy) were measured. We compared all parameters in the preoperative, incontinent, and continent periods.

RESULTS

MUL2 and MUL3 was significantly longer compared with MUL1, although no difference was found between MUL2 and MUL3. PRM3 thickness was significantly increased compared with PRM2 thickness. The Dx of the continence period was shorter than that of the incontinence period. The Dy of the continence period was longer than that of the incontinence period.

CONCLUSION

The PRM thickened and the bladder neck moved upward and forward during the continence period. The changes in PRM thickness and the position of bladder neck may play an important role in the recovery of continence after RP.