A Study Of MRI In Traumatic Posterior Urethral Stricture

Objective:Nowdays,traffic accident and trauma grow in number ,especially the probability of pelvic fracture and urethral injury increases in war.Accord to the documents there is 10% urethral injury appeared after pelvics fracture,most of the posterior urethral injury will come into urethral stricture.Posttraumatic pelvic anatomy can be distorted.The length,location of the posterior urethral stricture or oblieration,the depth of periurethral scar involved and duplicating features,all of which are important factors for determining appropriate therapy and ultimate prognosis.Standard evaluation before urethaoplasty includes urethrography with combined antegrade and retrograde,sonography.However they can not accurately define the length of urethral stricture/obliteration.Little information about prostate postion or pelvic fibrosis is obtained.It is important to the treatment.This study is to assess the role of MRI in the diagnosis,choice of treatment and the outcome about surgery of traumatic posterior urethral stricture or obliteration.Our objectives are:1. Patients with posterior urethral sticture underwent MRI of the pelvis. Determine the location,length of posterior urethral stricture and the depth of scar involved.Sagittal views can define the degree of prostatic dislocation in the superinferior and the relatoinship of prostatic apex and symphysis pubis.Compare theappearances among MRI and conventional cystourethrography and the findings in surgery;2. To assess the role of MRI in defining the surgical approach ,Determine the most appropriate surgical approach for reconstruction by MRI,and compare it with the real surgical approach;3. To evaluate the role of MRI in determining the outcome of operation.Patients underwent MRI at one month after surgery .That detects if there are relic posterior urethral scar,and compare it with the finding through urethrography.Methods:17 patients with stricture or obliteration of prostatomembranous urethral from pelvic crush injury underwent MRI of pelvis before and post open urethroplasty to evaluate the lengthen of the stricture the depth of periurethral scar involved . One volunteer with no urologic symptoms underwent MR imaging to illustrate normal pelvic anatomy.All patients underwent cystography and retrogrde urethrography.Of the MRI scaning 17 patients were performed with a Siemens 1.5 Tesla unitThe scaning included transaxial continuous 5mm.slices with Tl-weighted spin-echo imaging (repetition time mesec/echo time mesec=654/10),T2-weighted imaging (2500/70),and sagittal T2-weighted spin-echo imaging(2500/70),as well as sagittal ,coronal and transaxial Tl-weighted spin-echo imaging(592/ll) after injected.All the patients underwent voiding crystourethrgraphy and retrograde urethrography before and after operation. Result:The volunteer with no urologic symptoms underwent MR imaging can reveal normal pelvic anatomy .Pelvic MRI can accurately define the pelvic anatomy after crush injury MRI can determined prostate position and the relationship to symphysis pubis ,MRI correctly revealed the length of the urethral stricture and displace ofprostatic apex .The correlation coefficients of finding at MRI and surgery for measurement of the length of urethral stricture is 0.96. The correlation coefficients of finding at urethrgraphy and surgery for measurement of the length of urethral stricture is 0.90.At the same time conventional radiographic study can not demonstrate pelvic anatomy and posterior urethral fibrosis.lt can not define the location of prostatic apex.Pelvic MRI can provide useful preoperative information that can not be obtained by conventional radiographic study. The finding at MRI can determine the most appropriate surgical approach.Post operation MRI can reveal if the urethral scar was completely ablated,and the location of the relic scar. Conclusion:MRI can accurately define the pelvic anatomy > the length of the urethrostenosis and the depth of periurethral scar involved after crush injury as well as the location of prostatic apex and the relation with symphysis pubis.MRI is not painfuLAlougth it is expenseful,but MRI tian assess posttraumatic pelvic anatomy that provide better plan for the surgical reconstruction of complex posterior urethral stricture.At the same time MRI at postoperation can detect the urethral pattern and the relic scar of urethral wall.The appearance of MRI is very useful to evaluate postoperative effect objectively.