The Egyptian Journal of and (2015) 46, 199–204

Egyptian Society of Radiology and Nuclear Medicine The Egyptian Journal of Radiology and Nuclear Medicine

www.elsevier.com/locate/ejrnm www.sciencedirect.com

ORIGINAL ARTICLE Magnetic resonance urethrography versus conventional retrograde urethrography in the evaluation of : Comparison with surgical findings

Tarek Khalaf Fath El-Bab a, Ehab Mohamad Galal a, Amr Mohamad Abdelhamid a, Mohammed Farghally Amin b,* a Department of Urology, Minia University, Minia, Egypt b Department of Radiology, Minia University, Egypt

Received 8 January 2014; accepted 25 October 2014 Available online 6 December 2014

KEYWORDS Abstract Back ground: Urethral stricture means fibrous scarring of the caused by collagen Urethral stricture; and fibroblast proliferation. Magnetic resonance urethrography was emerging as a new modality for MR urethrogaphy; imaging the male urethra. Conventional retrograde Objectives: To evaluate the accuracy of MR urethrography in comparison to the conventional ret- urethrography rograde urethrography (RUG) in the evaluation of urethral stricture in comparison with surgical findings. Design, setting and participants: This prospective study was done in the period from Jan- uary 2010 to March 2012 including 20 male patients with initial diagnosis of anterior urethral stric- ture (diagnosed by RUG). Both newly diagnosed and recurrent cases were included regardless of the etiology of stricture. The mean age was 49.6 ± 16.4 years (ranged from 19 to 70). All patients were evaluated by conventional retrograde urethrography (RUG) and magnetic resonance urethrogra- phy (MR urethrography). Outcome measurements and statistical analysis: Magnetic resonance urethrography images were analyzed, focusing on the signal intensity, location and length of the stricture. Additionally, MR findings were evaluated regarding the urethra proximal to the stricture, the corpora spongiosa sur- rounding the stricture, adjacent organ injuries, and the associated complications. Data obtained were compared with operative findings in all patients. Results and limitations: The mean stricture length as measured by MR urethrography and RGU was 1.32 ± 0.85 and 1.75 ± 1.02 respectively with a significant difference (p < 0.001). The mean intra-operative stricture length was 1.29 ± 0.83. MR urethrography was accurate in 19 patients

Abbreviations: RUG, retrograde urethrography; MR urethrography, magnetic resonance urethrography * Corresponding author. E-mail address: [email protected] (M.F. Amin). Peer review under responsibility of Egyptian Society of Radiology and Nuclear Medicine. http://dx.doi.org/10.1016/j.ejrnm.2014.10.008 0378-603X 2014 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier B.V. All rights reserved. 200 T.K. Fath El-Bab et al.

(95%) while RUG was accurate in 15 patients (75%). This study has some limitations, firstly, a small number of patients are involved in this study, secondly, a 1 T magnet is used and finally, inter- observer agreement was not obtained. Conclusion: MR urethrography has a higher diagnostic accuracy in the detection of urethral stric- ture length than conventional RUG, that is crucial for proper selection of treatment modality. 2014 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier B.V. All rights reserved.

1. Introduction leg) bent from the knee and flexed toward the abdomen. The penis was placed laterally over the proximal thigh with moder- Generally, the term urethral stricture means fibrous scarring of ate traction. The entire length of the urethra was assessed for the urethra caused by collagen and fibroblast proliferation (1). any narrowing or abnormal fistulous communications. After The causes of anterior urethral strictures are mostly inflamma- gland sterilization, the urethra was filled by a 50 ml syringe tory (infectious urethritis, balanitis xerotica obliterans), trau- using 25 ml of contrast material (Telebrix 300 Meglumine; matic (straddle injury, iatrogenic) and less commonly Guerbet, Aulnay-sous-Bois, France) mixed with 25 ml of nor- congenital (2). mal saline. Images were obtained with the patient in the obli- Several diagnostic tools are available for imaging of the que position during maximum urethral distention. Also A-P urethra, of which retrograde urethrography (RUG) is the pri- films are obtained. mary imaging modality for evaluating urethral stricture dis- eases, however it has certain limitations like being invasive, 2.2. MR urethrography poorly detecting the accurate length of stricture and the extent of spongiofibrosis (3). Magnetic resonance (MR) urethrography and sonoureth- It was performed 4–10 days after RUG. rography were introduced as newer modalities for imaging the male urethra (4). Sonourethrography has proved to be 2.2.1. Technique accurate in the diagnosis of anterior urethral stricture, but it has certain limitations such as its small field of view and diffi- We used the technique of Schulam et al. (6). All patients were culty in urethral lumen delineation (5). instructed to remove all metallic articles, e.g. coins and keys. On the other hand, MR has the ability to delineate clear ana- They were asked about the presence of metallic prosthesis, tomical details regarding the urethra and periurethral tissue with coils or implants or any other articles interfering with MRI three dimensional orientation of the lesion (6). However, very examination. The examination was done with the patient in few studies evaluated the accuracy and diagnostic capability of supine position; the penis was positioned anteriorly and taped MR urethrography in the anterior urethral stricture. to the abdominal wall beneath the surface coil after injection The aim of this study is to evaluate the diagnostic capability of sterile gel into the urethra. MR images were obtained by of MR urethrography in comparison to the conventional RUG using a 1.0-T MR imaging device (Gyroscan, Intera, Philips, in anterior urethral stricture, using surgical findings as a gold Netherlands) and a pelvic phased-array coil. The MR imaging standard. protocol consisted of a sagittal T1 (TR msec/TE msec 400/20) and T2-weighted fast spin-echo sequence (TR msec/TE msec 3000/99) and axial T2-weighted fast spin-echo sequence 2. Materials and methods (3200/99; field of view, 24 cm; matrix, 512 · 264; section thick- ness, 3 mm; and section gap, 0.1 mm). This prospective study was done in the period from January 2010 to March 2012 and included 20 patients with anterior urethral stricture (diagnosed by RUG). Both newly diagnosed 2.3. Image analysis and recurrent cases were included regardless of the etiology of stricture. Patients were informed about the nature of different MR urethrography images were analyzed, focusing on the sig- diagnostic modalities used to diagnose their strictures. All nal intensity, location and length of the stricture. Additionally, patients gave a written consent for intervention. MR findings were evaluated regarding the urethra proximal to RUG and MR urethrogram were performed for all patients the stricture, the corpora spongiosa surrounding the stricture, prior to the intervention and results were interpreted by one adjacent organ injuries, and the associated complications. radiologist who has 15 years of experience in doing RUG Stricture length was measured along the long axis of the and 10 years of experience in interpreting MR urethrogram. fibrotic segment shown as low signal intensity on the sagittal Institutional Review Board approval was obtained prior to T2-weighted images. the start of the study by the research committee for Ethics. Open was performed in all patients (end to end anastomosis in 15 and augmented urethroplasty in 5 2.1. Technique of RUG patients). The strictured segments were adequately measured intra-operatively. The patient was positioned on a fluoroscopy table in a right or Radiologic data obtained were compared with operative left oblique position, with the right or left leg (the underside findings in all patients. Magnetic resonance urethrography versus conventional retrograde urethrography 201

Diagnostic accuracy of the two techniques was defined as phy, with the difference found to be significant (p < 0.001). the sum of positive and negative cases divided by total number The mean intra-operative stricture length was 1.29 ± 0.83 of cases. (Figs. 1–3). RUG was combined with a micturition study to measure In comparing the mean intra-operative stricture length with the defect. Measuring of urethral stricture length at ascending the mean length measured by RUG, the difference was found urethrography was done using the Magic View Picture Archiv- to be significant (p 0.02), while it was non significant (p 0.23) ing and Communicating System (PACS; General Electric, Mil- when compared with that measured by MR urethrography waukee, WI) after measurement calibration. Processing of the (Tables 1 and 2). images was done at a separate work station using the CT data MRU detected extensive spongiofibrosis in 5 cases (4 cases as Digital Imaging and Communications in Medicine with short segment and one with long segment stricture) (DICOM) files, three-dimensional reconstructed images were (Fig. 4). made using the V-works (version 3.0) program. The basic func- On the basis of MR findings, a stricture of 1.5 cm or less tions of V-works are as follows: was considered as short stricture, while a stricture of more than 1.5 cm was considered as long stricture. We have 15 (1) The system can reconstruct three-dimensional models of patients with short stricture and five patients with long stric- human organs from various data sources, such as CT ture (Fig. 5). The accuracy of MR and conventional RUG and MRI. was 95% and 75% respectively. (2) Users can manipulate the models using a variety of interactive functions. For example, a user can browse 4. Discussion a model using a mouse, navigate inside the model, or examine a cross-sectional view by registering and over- Sung et al., were the first to use the term MR urethrography, lapping a 2D image on a three dimensional model. that is sterile lubricating jelly instilled retrograde into the distal (3) Using the V-works simulation module, a user can create portion of the urethra through the external urethral meatus to operation plans using a marking, measurement, cutting, allow MR depiction of the distal end of a urethral stricture (7). and movement functions. We performed various mea- Urethral stricture is generally defined as any obstructive surements on three-dimensional reconstructed images fibrous scarring of the urethra (1). There are many treatment using V-works 3.0 program. options for the urethral stricture disease however; the choice

of the best one should be done according to many factors. Statistical analysis of data was done using SPSS , version As the stricture length is the most critical of these factors, great 12. effort should be taken to preoperatively clarify it (8,9). Other factors that also contribute to the surgical decision are the eti- 3. Results ology of current pathology, presence of spongiofibrosis and its extent, recurrent cases, surgeon’s experience and preference Twenty male patients, with anterior urethral stricture were (10,11). included. The age of patients ranged from 19 to 70 years, with However accurate estimation of the stricture length may be a mean age of 49.6 ± 16.4. affected by certain factors such as patient positioning, degree The mean stricture length measured by conventional RUG of penile traction and force of contrast injection which may was 1.75 ± 1.02, while it was 1.32 ± 0.85 by MR urethrogra- lead to a false diagnosis of urethral stricture (12–14). Even

Fig. 1 (a) Anterior RUG of a 60 year old male showing about 2 cm stricture of anterior urethra. (b) Sagittal T2-weighted MR image with ST = 4 mm demonstrates more than 2 cm anterior urethral stricture (black arrow head) surrounded by area of low signal intensity. 202 T.K. Fath El-Bab et al.

Fig. 2 (a) Images obtained in a 63-year-old man showing right anterior oblique RGU long segment anterior urethral stricture. A urethral diverticulum is seen bulging from the membranous urethra. (b) Sagittal T2 weighted image of male (55 years) showing urethral diverticulum (white arrow).

Fig. 3 Sagittal T2 weighted image of a male (24 years) showing well delineated urethra proximal to the dilated distal urethra compared with completely obliterated bulbous urethra (white arrows) (a) at conventional RGU (b).

Table 1 Comparison between RUG and intraoperative stric- ture length in centimeters. Variables Mean ± SD P-value Stricture length in RUG 1.75 ± 1.02 0.02* Intraoperative stricture length 1.29 ± 0.83 * Significant.

Table 2 Comparison between MR urethrography and intra- operative stricture length in centimeters. Variables Mean ± SD P-value Stricture length in MR urethrography 1.32 ± 0.85 0.23** Intraoperative stricture length 1.29 ± 0.83 ** Non significant.

Fig. 4 Sagittal T2 weighted image of a male (35 years) showing when following the standard technique, there are still fallacies an evident low signal intensity area of spongiofibrosis at the in stricture length estimation (15). The limitations of RGU proximal part of the anterior urethra extending to the membra- with VCUG have been reported frequently. It often cannot nous urethra. Magnetic resonance urethrography versus conventional retrograde urethrography 203

MR urethrography provided extra, clinically valuable data on some patients. The cause of the different results may be that the strictures in their cases were mainly partial and relatively short. The major role of MR urethrography is in revealing a com- plete or long defect because estimating a complete or long defect not uncommonly results from poor filling of the pros- tatic urethra with contrast medium when using RGU with VCUG. MR urethrography also has the problem of possibly not depicting the urethral portion proximal to the stricture, as noted with conventional RGU combined with VCUG (16). However, this may be overcome because T2-weighted images after injection of gel into the urethra provide high con- trast resolution with good depiction of the stricture proximal to the distended distal urethra and the intact surrounding structures, such as the corpora spongiosa or prostate. Spongiofibrosis is another critical determinant of appropri- ate therapy and ultimate prognosis. Treatment selections have been reported according to the degree of spongiofibrosis in patients with full-thickness spongy tissue fibrosis (16). The great advantage of MR urethrography over RGU with VCUG Fig. 5 Sagittal T2-weighted MR image with ST = 4 mm show- is assessment of periurethral and extraluminal changes. In this ing stricture to be about 2 cm and to have low signal intensity study we have five patients with spongiofibrosis in which MR involving the anterior urethra (white arrows). urethrography allows an accurate evaluation of fibrosis with actual depth and location. provide an accurate determination of the defect length because Sung et al. (19) in their series reported that, MR urethrog- of poor prostatic urethral filling and it provides little informa- raphy has a significantly lower incidence of fallacies in urethral tion on the extent of corpus spongiosal fibrosis or prostatic dis- stricture length than conventional RGU either alone or in placement. (3). combination with voiding . Sung et al., stated that the anterior and proximal portions Also, Oh et al. reported that MR findings can cause a of the posterior urethra are rarely shown on MR images. To change in the surgical procedure in 11 of 25 patients due to overcome the limitation of conventional MR imaging and bet- defect length and spongiofibrosis. The surgical procedure ter define the extent of the urethral stricture disease the urethra had previously been determined by findings on conventional can be distended with sterile lubricating jelly instillation. This RGU. It was useful for selecting the most appropriate surgical method was easy to perform and well tolerated by all patients. procedure (20). (7). This study has some limitations, firstly, a small number of In this study, the method as described by Schulam et al. (6) patients involved in this study, secondly, a 1 T magnet is used was used. Moreover, we measured the stricture length using and finally, interobserver agreement was not obtained. computed (with the aid of the Picture Archiving and Communicating System) to get the most accurate mea- 5. Conclusion surements possible. MR urethrography was suggested to be an extra radiolog- ical diagnostic tool for the urethral stricture disease (5,6).In MR urethrography has a higher diagnostic accuracy in the this study sterile gel was used to distend the urethra which is detection of urethral stricture length than conventional the same technique used by Osman et al. and El ghar et al. RUG, that is crucial for proper selection of treatment (17,18). This can give an easier and more comfortable disten- modality. sion of the urethra in comparison to saline that was previously used by Pavlica et al. (5). Conflict of Interest In this study we compared the stricture length measured by RUG and MR urethrography with the intra-operative stricture All authors state that there are no conflicts of interest in the length. MR urethrography allows an accurate estimation of manuscript, including financial, consultant, institutional and urethral stricture length, in great agreement with that mea- other relationships that might lead to bias. sured intraoperatively (95% accuracy). El-ghar et al. stated that MR allows an accurate estimation of urethral length in their study in good agreement with that measured by endos- References copy (18). Narumi and colleagues in 1993 reported that the stricture length was accurately measured in 85% of patients (1) Gallentine ML, Morey AF. Imaging of the male urethra for stricture disease. Urol Clin North Am 2002;29:361–72. at MR urethrography. (2) Pansadoro V, Emiliozzi P. 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