Magnetic Resonance Imaging Study Of Female With Stress Urinary Incontinence

Objective:Stress urinary incontinence (SUI) is due to pelvic floor disfunction, most found in women. On the pathogenesis of SUI have many theories, including the pressure transmission theory, "hammock" hypothesis,and the integral theory. These theories consider that SUI occurs because of the urethra supporting structure defects. Urethral support ligaments and the ani levator muscles control urine, urethral mobility connects with urethral support ligaments and the levator ani muscles. The composition of the urethral support ligaments is still controversial. MRI can show the urethral support structures well. Using dynamic MRI we observe the composition, morphology and courses of the urethral support ligaments and ani levator muscles, and then compare with the patients with SUI. In addition, the SUI patients who accepeted TOT treatment before and. after operation 1 week had given MRI examination to understand the value of MRI in evaluating postoperative effect. Materials and Methods:28 healthy volunteers and 16 SUI patients in which 7 cases with POP accepted static and dynamic pelvic MRI examination. Static MRI observes urethral ligaments, dynamic MRI observes urethral activity and morphological changes of levator ani muscle, and under two states measure H line, M line, diameter of pelvic diaphragm, urethral length, urethral tilt angle, posterior urethrovesical angle, retropubic space, the distance from urethrovesical junction to the PCL and levator plate angle. The measurement results of groups were statistically analyzed. The datas according with normality using mean±standard deviation descriptions, between two groups using paired t test and two independent sample t test. Non-normal data using the M, P25 and P75 for the statistical description, between two groups using two independent sample rank sum test. All hypothesis testing standards were a= 0.05.Results:1. Normal static MRI performance of urethral support structures The urethral support ligaments in T2WI are slightly low signal. Periurethral ligament originating from the inner side of puborectalis, running close to the ventral urethra; paraurethral ligament connecting the lateral wall of urethra to the periurethral ligament; pubourethral ligament originating from the ventral urethra to the posterior aspect of the pubic bone, was suspended with sample; suburethral ligament lying dorsal urethra hammock-like structure, connecting the urethra and pelvic arcus tendinous fasciae. The urethral support ligaments fix urethra and prevent SUI. Ani levator muscles compose of puborectalis, pubococcygeus and iliococcygeal muscle, in T2WI muscles showed a moderate signal. Levator ani muscle contraction can resist the increased abdominal pressure and maintain normal organ function and location.2. Normal dynamic MRI changes of urethral support structures Healthy women ani levator muscles had no significant morphological changes, diameter of pelvic diaphragm, the H line, M line, posterior urethrovesical angle, retropubic space and the distance from bladder neck to the PCL increased slightly after force, urethral tilt angle, after force increase lightly. Levator plate always parallel to PCL.3. Urethral support structures in static and dynamic MRI in patients with SUI SUI patients urethral support ligament changes, including laxity or rupture.Morphological changes of the levator ani is obviously, diameter of pelvic diaphragm increases, diaphragmatic hiatus was "O" shape in SUI with POP. H line> 6cm, M line> 2cm, levator plate caudal tilt average 20°. In SUI patients after force urethral length shorten, most or all of the urethra below the inferior edge of symphysis pubis; urethral inclination angle and posterior urethrovesical angle increase.4. SUI patients before and after TOT 1 week MRI imaging examination results The modality of urethra support ligaments did not change, postoperative urethral activity improved, but the difference was not statistically significant. Conclusion: 1. MRI can better show the morphology of four urethral support ligaments and levator ani muscles,and can objectively evaluate the functionality status of the levator ani and urethral activity degree, and thus supply imaging evidence for preoperative diagnosis of SUI.2. MRI can reflect the changes of urethral support structure and urethral activity of post-operative patients with SUI. MRI has a role in evaluation of curative effect of surgery. By increasing the number of cases and extending follow-up observation period, MRI is expected to give an objective image evaluation in surgical effect.