S. SCHUETTOFF*, D. BEYERSDORFF, A. GAURUDER-BURMESTER and R. TUNN

Transcription

1 ltrasound Obstet Gynecol 2006; 27: Published online in Wiley Intercience ( DOI: /uog.2781 isibility of the polypropylene tape after tension-free vaginal tape (TT) procedure in women with stress urinary incontinence: comparison of introital ultrasound and magnetic resonance imaging in vitro and in vivo. CHETTOFF, D. BEYERDORFF, A. GARDER-BRMETER and R. TNN Department of Obstetrics and Gynecology, Carl-Gustav-Carus-niversität Dresden, Department of Radiology, Charité Medical chool, Humboldt-niversität zu Berlin and Department of rogynecology, German Pelvic Floor Center, t. Hedwig Hospitals, Berlin, Germany KEYWORD: magnetic resonance imaging; tension-free vaginal tape; ultrasound; urinary incontinence surgery ABTRACT Objective To determine whether introital sonography and magnetic resonance imaging (MRI) after TT (tension-free vaginal tape) insertion can depict the polypropylene tape, and thus be used for patient follow-up. Methods The study comprised an experimental part, which investigated in-vitro visualization of the polypropylene tape in a model (phantom), and a clinical part, in which 20 women (mean age, 53.4 years) with clinically and urodynamically proven stress urinary incontinence without prolapse were investigated by introital ultrasound and MRI before and 13 months after the TT procedure. Results In the phantom, the polypropylene tape was depicted with a low signal intensity by MRI and as a highly echogenic structure by ultrasound. In the clinical study, introital ultrasound in a mediosagittal orientation depicted the vaginal tape in all patients: it was located under either the midurethra (n = 16) or the lower urethra (n = 4), and in either the muscular coat of the urethra (n = 8) or in the urethrovaginal space (n = 12), the tape was either flat (n = 6) or curled up (n = 14), and there was no retropubic visualization of the tape. Overall, depiction by MRI was limited, and was poorer in comparison with ultrasound, especially when the tape had a subor paraurethral location. Retropubically, however, MRI identified the tape near the periosteum of the pubic bone (55% of cases), in the retropubic space (37.5% of cases), or near the bladder wall (7.5% of cases). Conclusion onography is recommended for evaluation of the suburethral and paraurethral tape portions, while MRI is suitable for retropubic evaluation after the TT procedure. Copyright 2006 IOG. Published by John Wiley & ons, Ltd. INTRODCTION Tension-free vaginal tape (TT) insertion according to lmsten et al. 1 aims at stabilizing the midurethra during stress in women suffering from urinary stress incontinence. This theoretical concept is confirmed by long-term follow-up data and cure rates of 81.3% 2. It is generally accepted that positioning of the tape under the midurethra is important to the success of the procedure, although there is no evidence confirming that the polypropylene tape is located under the midurethra in patients who are cured, but not in patients with recurrence. Kaum and Wolff 3 even suggested that midurethral placement might not be as important for the success of the procedure as was previously thought. It has been suggested that complications may arise when the tape is misplaced relative to the urethra and urinary bladder, and such a correlation has been confirmed in initial studies 4. Kuuva and Nilsson 5 showed that complications can be reduced, but they cannot be prevented altogether, when the intervention is performed by an experienced operator. While postoperative voiding dysfunction may be attributable to misplacement of the polypropylene tape relative to the urethra 6, a tape too close to the urinary bladder is more likely to cause de novo urge. rge symptoms are a frequent problem after TT insertion but respond only poorly to symptomatic treatment. Thus postoperative imaging might be important to exclude Correspondence to: Dr R. Tunn, German Pelvic Floor Center, t. Hedwig Hospitals, Große Hamburger tr. 5-11, D Berlin, Germany ( r.tunn@alexius.de) Accepted: 12 March 2005 Copyright 2006 IOG. Published by John Wiley & ons, Ltd. ORIGINAL PAPER

2 688 chuettoff et al. misplacement of the vaginal tape as a possible cause of these symptoms. Based on the experience gained so far and the wide availability of sonography, introital or perineal ultrasound seems to be the most suitable modality for this purpose. While good visualization of the polypropylene tape in suburethral and paraurethral positions has been confirmed 7 9, we are not aware of any investigations concerning the sonographic evaluation of the tape in the retropubic space and its topographic relationship to the urinary bladder. Only Krissi et al. 10, using magnetic resonance imaging (MRI), have evaluated the topography of TT relative to the bony pelvis and the pelvic vessels. The aim of this study, therefore, was to investigate whether the position of the polypropylene tape relative to the urethra and urinary bladder can be evaluated by means of introital sonography. MRI served as the reference method and to identify possible supplementary indications for both imaging modalities. MRI appeared to be a suitable candidate for assessing tape position as it enables excellent depiction of the muscular and connective tissue structures of the pelvic floor and urethra. Prior to the clinical study, a phantom experiment was performed to evaluate in vitro the appearance sonographically and on MRI of the polypropylene tape and its demarcation from surrounding tissue structures. Moreover, the phantom study served to optimize MR pulse sequence parameters, which was deemed necessary as no methodological data are available in the literature. METHOD Phantom study The carrier medium of the phantom consisted of a water fat mixture with signal characteristics similar to those of human fatty tissue on MRI. The polypropylene tape (original TT, Gynecare Division, Ethicon Inc., omerville, NJ, A) was placed in this mixture without tension. Before it was imaged, the phantom with the tape was placed in a vacuum chamber for 4.5 h at 38 Cto eliminate air bubbles, which would have caused artifacts on MRI. The phantom was examined with the same MRI pulse sequences and the same vaginal ultrasound scanner as were patients in the clinical study, as described below. Clinical study Twenty women with proven stress urinary incontinence were selected for stress urinary incontinence surgery (TT insertion under local anesthesia with analgesia and sedation). The diagnosis was based on history (Grade II), clinical findings (positive stress test), and urodynamic testing. ensory or motor urge symptoms were excluded in all women by means of cystometry performed using the Ellipse urodynamic measurement system (Andromeda, Taufkirchen/Potzham Germany) according to standards of the International Continence ociety. MRI was performed in all women as part of their preoperative diagnostic work-up, after informed consent had been obtained. Women who additionally had clinically relevant urogenital prolapse or had undergone prior urogynecological surgery were excluded from the study. The study was approved by the ethics committee of Charité Hospital, Humboldt-niversität, Berlin. All women underwent preoperative and postoperative introital ultrasound in the semisitting position (with standardized bladder filling of 300 ml) using a Cheetah 2000 (B-K Medical Medizinische ysteme GmbH, Quickborn, Germany) ultrasound machine equipped with a 5-MHz vaginal sector probe with an emission angle of at least 90. The position of the urethra at rest was determined by measuring the inclination angle, alpha (angle between urethral axis and body axis), and the posterior urethrovesical angle, beta (angle between urethral axis and floor of bladder). The mediosagittal scan served to evaluate the visibility of the polypropylene tape, and its width and thickness, configuration, and topographic position relative to the urethra (Figure 1a; for sonographic evaluation, the urethra is subdivided into distal, middle and proximal portions). In addition, the tape distance (from the intersection of longitudinal and transverse axes of the tape) was determined relative to the middle of the urethral lumen and the lower border of the pubic symphysis. MRI was performed with the patient supine and her legs supported in a slightly elevated position. Images were acquired at 1.5 Tesla, without contrast medium administration, using a body phased-array coil (Magnetom ision, iemens, Erlangen, Germany). A standardized protocol with the following sequences and parameters was used: proton-density-weighted turbo spinecho (TE) sequence with a repetition time (TR) of 2200 ms, an echo time (TE) of 15 ms, right left phase encoding, an axial slice orientation with a field of view of mm, an image matrix of , a slice thickness of 4 mm, and an interslice gap of 0.8 mm (distance factor, 0.2); sagittal T2-weighted TE sequence (TR, 4500; TE, 112) with a matrix (Figure 1b). Axial, coronal and sagittal images were used for evaluation of the periurethral and perivesical portions of the vaginal tape. To detect edema as an indirect sign of inflammation, an additional turbo inversion recovery magnitude sequence (TIRM) with a short inversion delay of 150 ms was used (TR/TE, 4000/30; slice thickness/gap, 5/5 mm). This sequence emphasizes tissue fluid. In order to confirm the reproducibility of the criteria used for evaluation,.. and D.B. interpreted the images by consensus without knowledge of the initial interpretation by.. The observers evaluated the topography of the vaginal tape relative to the urethra and urinary bladder in all three orientations (axial, coronal and sagittal), as well as tissue reactions to the vaginal tape (TIRM images). tatistical analysis The data were recorded using Excel 97 (Micorsoft Corp., Redmond, WA, A). tatistical analysis, including Copyright 2006 IOG. Published by John Wiley & ons, Ltd. ltrasound Obstet Gynecol 2006; 27:

3 ltrasound vs. MRI after TT insertion 689 Table 1 aginal tape dimensions measured by introital ultrasound and magnetic resonance imaging (MRI) in the phantom experiment Tape width (mm) Tape thickness (mm) In-vitro measurement Phantom (ultrasound) Phantom (MRI) Figure 1 Mediosagittal view by introital ultrasound (a) and magnetic resonance imaging (MRI) (b) of the polypropylene tape (arrows) with a flat configuration. The tape is located under the midurethra and is parallel to the urethral axis within the urethrovaginal space, appearing hyperechoic on ultrasound and with low signal intensity on MRI. Assignment of the vaginal tape to the upper, middle, or lower third of the urethra is indicated by the dottedlines.,vesicalneck;,urethra;,symphysis. tudent s t-test, correlation z-test and chi 2 -test for categorical data, was performed with P 9.0 for Windows (P, Chicago, IL, A). The probability of error was α = 0.05, yielding a significance level of P < α. RELT Phantom study Introital ultrasound depicted the tape in the carrier medium as an echodense mesh-like structure with the dimensions measured sonographically exceeding the manufacturer s specifications (Table 1; Figure 2a). Figure 2 Phantom experiment for investigating in vitro visualization by sonography (transverse view) (a) and magnetic resonance imaging (b) of the polypropylene vaginal tape in a water fat mixture. On sonography the structure appears hyperechoic (a). In both cases the longitudinal course and thickness (calipers/arrows) of the tape are evident. MRI depicted the polypropylene tape in the phantom as a smooth-edged, homogeneous structure of low signal intensity against the hyperintense water fat mixture. The measured dimensions corresponded to the manufacturer s specifications (Table 1; Figure 2b). Copyright 2006 IOG. Published by John Wiley & ons, Ltd. ltrasound Obstet Gynecol 2006; 27:

4 690 chuettoff et al. Clinical study The 20 women included in the prospective study had a mean age of 53.4 ± 10.5 (range, 35 75) years and underwent follow-up after a mean of 13 (range, 9 17) months. All 20 women considered themselves cured of stress urinary incontinence after the procedure. The stress test and pad tests were negative in all cases. Fifteen of the women could void without postvoid residual urine on the day of surgery and the other five could do so within the first 6 postoperative days. Four of these five women reported protracted voiding when they presented for follow-up. Postvoid residual urine of over 50 ml was excluded in all cases. With the urethra at rest, introital sonography identified the polypropylene tape under the midurethra in 16 women and under the distal urethra in four women. The vaginal tape was located in the urethrovaginal space in 12 women and at the level of the muscular layer in eight women. The tape was flat in six women and curled up slightly in another six; in the other eight, the tape was completely curled up, with a horseshoe configuration (Figure 3). The tape was seen parallel to the urethra in six women and at an angle relative to the urethra in eight women; in the other six, the tape was too curled for adequate assessment. The flat vaginal tapes were parallel to the urethra in 66% of cases, compared with only 33% of cases for the curled tapes. The measured vaginal tape width was 8.7 ± 1.8 (range, ) mm and the thickness was 2.3 ± 0.7 (range, ) mm. The distance of the tape (from the intersection of longitudinal and transverse axes) was 6.1 ± 1.5 (range, ) mm from the middle of the urethral lumen and 15.9 ± 2.1 (range, ) mm from the lower edge of the pubic symphysis. Introital ultrasound did not allow evaluation of the topographic relationship of the retropubic tape portion to the urinary bladder. MRI depicted the polypropylene tape under the midurethra in 15 women and under the lower urethra in the other five women. It was found to be located in the urethrovaginal space in 18 women and at the level of the muscular tunic in one instance. In one case topographic evaluation was precluded because of poor visualization of the tape. MRI did not allow evaluation of the configuration of the suburethral tape portions or of the topographic relationship of the tape to the urethra. The assessability of the retropubic tape portion is summarized in Table 2. Figure 4 shows the course of the vaginal tape at the periosteum of the posterior aspect of the pubic bone, in the retropubic space, and at the wall of the urinary bladder. The TIRM images excluded edema around the vaginal tape in all cases. Comparing introital ultrasound and MRI, both depicted the polypropylene tape under the middle urethra in 13 patients and at the lower urethra in two. Three vaginal tapes were depicted at the middle urethra by introital ultrasound and at the distal urethra by MRI and vice versa in another two cases. Figure 3 Mediosagittal introital ultrasound images of different tape configurations, with the tape flat (a), slightly curled up (b) and completely curled up (c). The arrows indicate the polypropylene tape., symphysis;, urethra;, bladder. Disturbed postoperative voiding and urge symptoms without incontinence correlated with the sonographic depiction of a curled up vaginal tape in the suburethral Copyright 2006 IOG. Published by John Wiley & ons, Ltd. ltrasound Obstet Gynecol 2006; 27:

5 ltrasound vs. MRI after TT insertion 691 Figure 4 Depiction of the retropubic portion of the vaginal tape ends (arrows) by magnetic resonance imaging (coronal proton-density-weighted images): (a) in a 61-year-old patient, showing the left end in the retropubic space and the right end extending up to the bladder wall; (b) in a 49-year-old patient, showing the right end just above the periosteum (left end not visible); (c) in a 36-year-old patient, showing the tape along the bladder wall on both sides; (d) in a 56-year-old patient, showing both ends of the tape within the retropubic space., retropubic space;, bladder. Table 2 Location by magnetic resonance imaging of the ends of the retropubic tape portion in 20 patients Right end of tape position in our study population (6/7 women). The visualization of the tape by ultrasound and MRI did not vary with patient age. Left end of tape at periosteum of pubic bone in retropubic space near bladder wall DICION At periosteum of n = 6 n = 5 n = 1 pubic bone Retropubic space n = 3 n = 3 n = 1 Near bladder wall n = 1 n = 0 n = 0 The TT procedure according to lmsten is a standardized minimally invasive surgical approach that aims at stabilizing the midurethra during stress. In our phantom experiment, the polypropylene tape was found to have Copyright 2006 IOG. Published by John Wiley & ons, Ltd. ltrasound Obstet Gynecol 2006; 27:

6 692 chuettoff et al. expected echogenicity at ultrasound, and low signal intensity at MRI. The same echogenicity and signal intensity confirmed that the surrounding connective tissue in vivo did not change the sonographic and MRI properties of the vaginal tape. This is also corroborated by histology 11, which excludes excessive connective tissue reactions along the tape. The TIRM images did not show hyperemia or edema in the vicinity of the vaginal tape, thereby providing indirect evidence for the absence of an inflammatory reaction. Our findings show that introital ultrasound is superior for evaluation of the periurethral tape position, while MRI is more suitable to depict the retropubic tape portion. The two diagnostic modalities thus have complementary indications in postoperative follow-up after a TT procedure. Prompt evaluation of the periurethral tape position by ultrasound is indicated in patients with disturbed postoperative bladder voiding, urge symptoms or dysuria. Identification of the vaginal tape near the bladder neck or in an intramural position or demonstration of a strongly curled up tape may provide clues as to the cause of the dysfunction and can thus help to establish the indication for vaginal tape revision. Published case reports suggest that there is a clinical association between disturbed postinterventional function and misplacement of the tape 6,12. Kociszewski and Bagci 4 discuss a possible relationship between a changed configuration of the TT and functional disturbances. It must be emphasized that the focus of our study was on investigating the potential of two imaging modalities, ultrasound and MRI, in the postoperative evaluation of the TT procedure, and that the number of patients investigated was much too small to establish any correlations between imaging findings and clinical symptoms. The MRI findings did not provide additional information on the periurethral course of the vaginal tape as compared with ultrasound. In this situation, sonographic evaluation was superior to MRI because the latter was impaired by partial volume effects and the fact that the tape and muscular coat of the urethra have similar signal intensities. In contrast, MRI enabled adequate evaluation of the position of the retropubic/paravesical portion of the vaginal tape, which is not accessible to evaluation by introital ultrasound. However, the results presented here do not justify the routine use of MRI for the evaluation of patients with disturbed bladder voiding function after a TT procedure. tudies with larger numbers of symptomatic patients are needed to establish definitive correlations between tape position and clinical symptoms (especially urge symptoms). Comparison of introital ultrasound and MRI showed an agreement of 75% in evaluating the tape position relative to the urethra (distal, middle or proximal third). This may be attributable to the technical limitations of MRI in depicting the polypropylene tape, which further corroborates the role of introital ultrasound in assessing the outcome of the TT procedure. A critical issue is the fact that not all vaginal tapes come to lie under the midurethra despite the use of a standardized surgical approach. The different tape positions could be due to the fact that in all women the vaginal incision is made at a predefined distance from the external urethral orifice, despite interindividual variation in urethral length. Therefore, it may be advantageous to determine the position of the bladder neck by means of balloon catheterization and to thus identify the midurethra for placement of the vaginal incision on an individual basis. On the other hand, Kaum and Wolff s 3 suggestion that correct midurethral tape positioning is not decisive for the success of the TT procedure also requires further investigation. REFERENCE 1. lmsten, Henriksson L, Johnson P, arhos G. An ambulatory surgical procedure under local anaesthesia for treatment of female urinary incontinence. Int rogynecol J Pelvic Floor Dysfunct 1996; 7: Nilsson CG, Falconer C, Rezapour M. even-year follow-up of the tension-free vaginal tape procedure for treatment of urinary incontinence. Obstet Gynecol 2004; 104: Kaum HJ, Wolff F. TT: On midurethral tape positioning and its influence on continence. Int rogynecol J Pelvic Floor Dysfunct 2002; 13: Kociszewski J, Bagci. TT sonographische beobachtungen im hinblick auf die korrekte lage und funktion des TTbandes unter berücksichtigung der individuellen urethralänge. Geburtshilfe Frauenheilkd 2003; 63: Kuuva N, Nilsson CG. A nationwide analysis of complications associated with the tension-free vaginal tape (TT) procedure. Acta Obstet Gynecol cand 2002; 81: Tunn R, Gauruder-Burmester A, Kölle D. ltrasound diagnosis of intra-urethral tension-free vaginal tape (TT) position as a cause of postoperative voiding dysfunction and retropubic pain. ltrasound Obstet Gynecol 2004; 23: Dietz HP, Barry C, Lim YN, Rane A. Two-dimensional and three-dimensional ultrasound imaging of suburethral slings. ltrasound Obstet Gynecol 2005; 26: Ng CC, Lee LC, Han WH. se of three-dimensional ultrasound scan to assess the clinical importance of midurethral placement of the tension-free vaginal tape (TT) for treatment of incontinence. Int rogynecol J Pelvic Floor Dysfunct 2005; 16: Tunn R, Petri E. Introital and transvaginal ultrasound as the main tool in the assessment of urogenital and pelvic floor dysfunction: an imaging panel and practical approach. ltrasound Obstet Gynecol 2003; 22: Krissi H, Adam JE, tanton L. MRI visualization of the female pelvis in the plane of the tension-free vaginal tape (TT) procedure. Int rogynecol J Pelvic Floor Dysfunct 2003; 14: Falconer C, öderberg M, Blombren B, lmsten. Influence of different sling materials on connective tissue metabolism in stress urinary incontinent women. Int rogynecol J Pelvic Floor Dysfunct 2001; 12 (uppl 2): Yang JM, Huang WC. onographic findings in a case of voiding dysfunction secondary to the tension-free vaginal tape (TT) procedure. ltrasound Obstet Gynecol 2004; 23: Copyright 2006 IOG. Published by John Wiley & ons, Ltd. ltrasound Obstet Gynecol 2006; 27: