CT Cystography with Multiplanar Reformation for Suspected Bladder Rupture: Experience in 234 Cases

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1 han et al. T ystography for Suspected ladder Rupture Genitourinary Imaging Original Research M E D E N T U R I L I M G I N G David P. N. han 1 Hani H. bujudeh 2 George L. ushing, Jr. 2 Robert. Novelline 2 JR 2006; 187: X/06/ merican Roentgen Ray Society Y O F han DPN, bujudeh HH, ushing GL Jr, Novelline R Keywords: bladder trauma, T cystography, multiplanar reformation DOI: /JR Received June 7, 2005; accepted after revision September 18, Presented at the 2005 annual meeting of the Radiological Society of North merica, hicago, IL. 1 Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Shatin, Hong Kong. ddress correspondence to D. P. N. han (chanponin@gmail.com). 2 Department of Radiology, Massachusetts General Hospital, oston, M T ystography with Multiplanar Reformation for Suspected ladder Rupture: Experience in 234 ases OJETIVE. T cystography has replaced conventional cystography in the evaluation of patients with suspected bladder rupture in most trauma centers. We performed this retrospective review to determine the accuracy of T cystography and the role of multiplanar reformation in the diagnosis of bladder injury. MTERILS ND METHODS. The patient cohort was composed of trauma patients with clinically or T-suspected bladder ruptures who were evaluated with T cystography using two different MDT scanners at our level 1 trauma center. The patients were identified through Folio, a radiology research tool software system. The T cystography results were compared with the findings at surgery, clinical follow-up, or both. RESULTS. etween January 1, 2000, and December 31, 2004, 234 patients were examined in our level 1 trauma center with T cystography. From the total of 234 examinations, 216 (92.3%) were interpreted as negative and 18 examinations (7.7%) were interpreted as positive. On the 18 positive examinations, 11 were extraperitoneal bladder rupture, five were intraperitoneal bladder rupture, and two were combined intraperitoneal and extraperitoneal bladder rupture. Surgical bladder exploration and repair were performed in nine of the 18 cases. Seven (77.8%) of the nine cases had operative findings consistent with the T cystogram findings. The overall sensitivity and specificity of T cystography in diagnosing bladder rupture were each 100%. For extraperitoneal bladder rupture, the sensitivity and specificity were 92.8% and 100%, respectively. For intraperitoneal rupture, the sensitivity and specificity were 100% and 99%, respectively. ONLUSION. T cystography is accurate for diagnosing bladder rupture. Sagittal and coronal multiplanar reformations may be helpful in identifying most sites of bladder rupture. ladder rupture is an uncommon injury, occurring in 10% of patients with pelvic fractures. However, 83% of patients with bladder rupture have a pelvic fracture [1]. ladder injuries can be categorized into several types: contusions, intraperitoneal rupture, extraperitoneal rupture, and combined intraperitoneal and extraperitoneal rupture. ontusion represents an intramural injury, with hematoma within the bladder wall. Extraperitoneal bladder rupture is more common, with an 80 90% frequency rate, whereas intraperitoneal bladder rupture occurs in 15 20% of patients. ombined rupture occurs in as many as 12% [2]. ccurate identification of bladder injury is of paramount importance for proper management. Surgical repair is required for intraperitoneal rupture and combined intraperitoneal and extraperitoneal rupture. atheter drainage is required for extraperitoneal rupture, whereas contusion can be managed conservatively. Delay in the diagnosis and treatment of bladder trauma may increase patient morbidity and mortality. Therefore, rapid diagnosis is essential for optimal patient management [3]. In the past, conventional cystography was considered the standard procedure for evaluating patients with suspected bladder injury [4 6]. However, it is time-consuming, cannot provide information regarding other pelvic structures, and is sometimes limited by the presence of overlying fracture fragments or fixation devices. T is now considered to be a diagnostic procedure of choice in the evaluation of abdominal and pelvic injury after blunt trauma. The conventional T protocol for abdominal trauma may or may not show the presence of bladder trauma because visualization of bladder rupture on T requires the bladder to be filled with fluid and under pressure. Therefore, if a conventional abdominal trauma T examination fails to show bladder rupture and 1296 JR:187, November 2006

2 T ystography for Suspected ladder Rupture bladder rupture is suspected, especially when water-dense fluid is seen in the peritoneal cavity, T cystography is indicated. The value of T cystography has been evaluated by other investigators [4, 5] who concluded that it was as accurate as conventional cystography in diagnosing bladder trauma. MDT was introduced in ompared with helical T, it can improve temporal and spatial resolution, decrease image noise, and provide longer anatomic coverage. Multiplanar reformation (MPR) is a planar recording of voxels used to provide alternate reformations for better anatomic delineation. The thin-section scanning in MDT allows the production of higher quality MPR images [7]. Prior investigations of T cystography had not emphasized the role of MPR. We hypothesize a better anatomic understanding of bladder injury can be achieved with sagittal and coronal images from MPR. We retrospectively evaluated the role of MPR in the diagnosis of bladder injury using MDT. The accuracy of MDT cystography was also evaluated. Materials and Methods pproval for this investigation was granted by our institutional human studies review board. Using Folio Views, version 4.2 (Folio Division of Open Market), a radiology research tool software system, Fig year-old man with extraperitoneal bladder rupture after motor vehicle collision., T cystography images (, axial;, coronal;, sagittal) show site of bladder rupture at right lateral wall (arrows) with contrast extravasation into extraperitoneal space (arrowheads). we identified 234 patients (142 males and 92 females; age range, years; mean age, 42.3 years) admitted to our level 1 trauma center between January 1, 2000, and December 31, 2004, for whom bladder ruptures were suspected and T cystography was performed. The mechanisms of injury included motor vehicle collision, n = 133; pedestrian stuck by motor vehicle, n = 49; fall, n =47; bicycle accident, n = 2; and gunshot injury, n =3. The medical records and T cystography images were reviewed. Variables recorded from medical records included patient age, sex, mechanism of injury, hematuria (gross or microscopic) at presentation, associated pelvic fractures, operative findings, and progress at clinical follow-up. JR:187, November

3 han et al. Fig year-old woman with intraperitoneal bladder rupture after motor vehicle collision., T cystography images (, axial;, coronal;, sagittal) show site of bladder rupture at dome (arrows) with contrast extravasation into peritoneal space (arrowheads). Note enlarged uterus with fibroids (F). Our standard T protocol for abdominal and pelvic trauma was as follows. efore the T examination, 3 cups of 1/4 oz meglumine diatrizoate (Gastrografin, ristol-myers Squibb) in 10 oz of water was given as an oral contrast agent. The Foley catheter was clamped to assist bladder filling. Scanning was performed after the power injection of 135 ml of IV contrast agent at a rate of 3 ml/s at 70 seconds delay from the level of diaphragm to the iliac crest, then from the iliac crest to the ischial tuberosities at a 120- second delay. Scanning parameters were detector configuration, mm; slice thickness, 5 mm; image spacing, 5 mm; and pitch, 6 for 4-MDT (Light- Speed Plus, GE Healthcare); and detector configuration, mm; slice thickness, 5 mm; image spacing, 5 mm; pitch, 0.938; and table speed, for 16-MDT (LightSpeed Pro16, GE Healthcare). T cystography proceeded afterward if there was suspicion of bladder trauma, for example, presence of pelvic fracture, low-density pelvic fluid, and clinically detected blood in the meatus. T cystography was performed by using a low-gravity drip infusion of ml of diluted water-soluble contrast agent (sterile injection of 40 ml of 60% water-soluble contrast agent into a 1-L bag of saline; the height of the reservoir was about 1.5 m) through the Foley catheter to the urinary bladder. fter complete filling of the bladder, scanning was performed from above the top of the iliac crest through the ischial tuberosities to include the entire bladder. The axial data were reconstructed with 2.5-mm slices at 2-mm intervals in the standard algorithm for the reformation. The axial T images and MPR images, including sagittal and coronal reformatted images of all cases, were retrospectively analyzed by one of the authors using a PS workstation (IMPX, gfa) JR:187, November 2006

4 T ystography for Suspected ladder Rupture Fig year-old man with intraperitoneal bladder rupture who was struck by motor vehicle., xial T cystography image shows contrast extravasation into peritoneal space (arrowheads), but exact site of rupture cannot be determined. and, oronal () and sagittal () T cystography images show site of bladder rupture at dome (arrows) with contrast extravasation into peritoneal space (arrowheads). D, Retrospective review of axial T cystography image at corresponding level shows possible location of rupture at bladder dome (arrow) with contrast extravasation into peritoneal space (arrowhead), but rupture is not well seen because scanning plane is parallel to bladder dome. The images were evaluated to assess the types of bladder injury (extraperitoneal rupture, intraperitoneal rupture, combined intraperitoneal and extraperitoneal rupture) and also the sites of bladder injury in different planes. These findings were compared with the operative findings and the progress of the patient s clinical condition during the hospital stay for example, any persistent hematuria, abdominal pain, and follow-up imaging (T or conventional cystography). Results total of 234 patients with suspected bladder trauma were examined on T cystography in this 5-year period. Eighteen (7.7%) of the 234 T cystograms were interpreted as positive for bladder rupture; 11 of those 18 were extraperitoneal ruptures (Fig. 1), five were intraperitoneal ruptures (Figs. 2 and 3), and two were combined intraperitoneal and extraperitoneal ruptures. There was no bladder contusion reported in this investigation. The mechanisms of injury were motor vehicle collision, n = 11; pedestrian stuck by motor D JR:187, November

5 han et al. vehicle, n =6; and fall, n = 1. Two patients (one extraperitoneal rupture and one intraperitoneal rupture) died shortly after admission because of multiorgan injury. The remaining 216 patients had negative T cystography results. Ten died afterward due to multiorgan injury. The remaining 206 patients had subsequent clinical follow-up that did not show evidence of bladder injury. Pelvic fractures were noted in 163 (70%) of the 234 cases in our study series. mong the positive cases on T, 14 (77.8%) of 18 had pelvic fracture; 11 patients had extraperitoneal bladder rupture, one patient had intraperitoneal rupture, and two patients had combined intraperitoneal and extraperitoneal rupture. ll of them had more than one fracture site. Twelve of the 18 cases had pubic rami fractures, 11 had sacral fractures, three had pubic symphysis diastasis, five had sacroiliac diastasis, two had iliac fractures, and five had acetabular fractures. No fracture was seen in three patients with intraperitoneal rupture and one patient with Fig year-old woman who was struck by motor vehicle., xial T cystography image shows site of bladder rupture at anterior wall (arrow) with contrast extravasation into extraperitoneal space (black arrowhead). Extravasated contrast agent posterior to bladder wall (white arrowhead) was thought to be intraperitoneal rupture component. Initial interpretation was combined intraperitoneal and extraperitoneal rupture. and, oronal () and sagittal () T cystography images show site of intraperitoneal bladder rupture (arrow) and extraperitoneal rupture (black arrowheads). Note extravasated contrast agent was underneath peritoneal reflection as shown in (white arrowheads), and there was no extravasated urine surrounding loops of bowel. combined intraperitoneal and extraperitoneal rupture. Gross hematuria was present in 46 of the 234 patients, including all 18 patients with bladder rupture. Microscopic hematuria was seen in 111 of the 234 patients and no hematuria in 77. No bladder injury was seen in these two groups of patients. ladder exploration and repair were performed in nine patients with positive T cystography results (three extraperitoneal rupture, four intraperitoneal rupture, two combined 1300 JR:187, November 2006

6 T ystography for Suspected ladder Rupture Fig year-old woman after motor vehicle collision., xial T cystography image superior to bladder level shows contrast extravasation into peritoneal space (arrowheads) outlined by adjacent bowel loops., xial T cystography image at bladder level shows a small amount of fluid lateral to bladder but no contrast extravasation is seen (arrows). T cystogram was interpreted as intraperitoneal rupture with probability of extraperitoneal rupture. Injury was confirmed to be combined intraperitoneal and extraperitoneal rupture by surgical bladder exploration. intraperitoneal and extraperitoneal rupture). The operative findings were consistent with the T cystogram findings in seven of the nine cases. In one of those cases, T was interpreted initially as combined intraperitoneal and extraperitoneal rupture but on surgical exploration was found to be extraperitoneal rupture only. However, on retrospective review only extraperitoneal rupture was seen on T (Fig. 4). In one of the nine cases, T was interpreted as intraperitoneal bladder rupture with contrast extravasation into the peritoneal space. small amount of fluid was seen in the extraperitoneal space lateral to the bladder wall but no contrast extravasation to the extraperitoneal space was seen. Operative exploration revealed combined intraperitoneal and extraperitoneal rupture (Fig. 5). The specific type of bladder rupture was therefore correctly identified on T cystography in seven of nine patients (77.8%). In the seven of 11 patients with extraperitoneal rupture, the treatment was conservative. Follow-up imaging performed 7 38 days after initial injury in six of the seven (three T cystography and three conventional cystography) did not show further rupture (Fig. 2D). The overall sensitivity and specificity of T cystography in diagnosing bladder rupture were both 100%. For detection of extraperitoneal bladder rupture, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of T cystography were 92.9%, 100%, 100%, and 99.5%, respectively. For detection of intraperitoneal bladder rupture, the sensitivity, specificity, PPV, and NPV of T cystography were 100%, 99.6%, 85.7%, and 100%, respectively. The axial images were retrospectively compared with coronal and sagittal images from MPR. One case (Fig. 4) with an initial diagnosis of combined intraperitoneal and extraperitoneal rupture was found to have only extraperitoneal rupture on exploration. The MPR images were retrospectively reviewed and showed no contrast extravasation in the peritoneal space. For the case with a T cystography diagnosis of intraperitoneal rupture but an operative diagnosis of combined intraperitoneal rupture and extraperitoneal rupture, the axial and MPR images were retrospectively reviewed (Fig. 5), but again no contrast extravasation was seen in the extraperitoneal space in any of the three planes. Through the axial images, we could identify the sites of bladder rupture in 14 of the 18 patients (11, extraperitoneal rupture; 1, intraperitoneal rupture; and 2, combined intraperitoneal and extraperitoneal rupture). In the remaining four patients with intraperitoneal rupture, the site of rupture was at the bladder dome but could not be well shown in axial images (Fig. 3). However, through the coronal and sagittal images from MPR we could identify all the bladder sites, including the four cases not seen in the axial images. Discussion One of the advantages of MDT is its MPR ability [8]. The coronal plane images may serve as a useful adjunct to the axial plane images. Images in the coronal plane are particularly appealing to surgeons because the orientation of structures is analogous to that encountered during exploratory laparotomy. Given such advantages, we think MDT with MPR may better delineate the bladder injury. onventional cystography has been regarded as the standard for the evaluation of bladder trauma. However, conventional cystography is sometimes difficult in a trauma setting, particularly if the patient is on a spinal board, and turning a patient with pelvic trauma may be not be possible. In addition, conventional cystography is time-consuming, cannot provide information on surrounding structures, and is sometimes limited by the presence of the overlying fracture fragment or fixation devices in pelvic fracture. JR:187, November

7 han et al. T is generally accepted as an imaging technique of choice for the evaluation of patients with multiple injuries, and the concept of integrating T scanners into the context of the emergency department has contributed to increasing the use of T for evaluation of multitrauma patients [2, 9]. T is therefore considered essential for bladder trauma assessment. In addition to the high level of diagnostic certainty, there is the further advantage of performing the entire examination at one location. The patient does not have to be transported from T room to fluoroscopy room for conventional cystography. The accuracy of T for evaluation of bladder trauma has been assessed. Mee et al. [10] reported two cases of missed bladder rupture by T in which the bladder was filled by the contrast agent in an antegrade fashion by clamping the Foley catheter while the delayed scan was taken. It was concluded that inadequate bladder distention was a limitation of T, and retrograde infusion of contrast agent was advocated. subsequent study by Lis and ohen [5] showed that T cystography is at least as accurate as conventional cystography in assessing bladder injury. In a prospective study by Peng et al. [4], which used T cystography to screen 55 patients with hematuria and blunt abdominal trauma, five patients were identified as having bladder rupture and the diagnoses were confirmed intraoperatively. There were no false-positive results. Diagnoses for the remaining 50 patients with negative T cystography results were confirmed on conventional cystography. In a retrospective review by Deck et al. [6], 44 of 316 patients had bladder rupture, and T cystography was used to identify 42 cases. The sensitivity, specificity, PPV, and NPV for T cystography in diagnosing extraperitoneal rupture were 97%, 100%, 100%, and 99%. The sensitivity, specificity, PPV, and NPV for T cystography in diagnosing intraperitoneal rupture were 78%, 99%, 70%, and 99%. In our study using MDT, the results were comparable with the study by Deck et al. [6] using helical T. There were no false-negative results in our study. The sensitivity of T cystography in diagnosing intraperitoneal rupture in our study was higher than that found by Deck et al. (100% vs 78%), whereas the specificity remained the same (both 99%). We postulated the use of MDT may increase sensitivity with no change in specificity in diagnosing intraperitoneal bladder rupture. The diagnosis of intraperitoneal bladder rupture is important because surgical repair is required, and delay in diagnosis or treatment may increase morbidity and mortality. There were two cases with discrepancy in the type of bladder rupture. The first case was interpreted as combined intraperitoneal and extraperitoneal rupture but exploration found both to be extraperitoneal rupture. The images were retrospectively reviewed. They were initially misinterpreted because there was extravasated contrast agent posterior to the bladder. However, on sagittal MPR images, the extravasated contrast agent was confined to the extraperitoneal space because all the contrast agent was underneath the peritoneal surface (Fig. 4). nother difficult case showed extravasated contrast agent in the intraperitoneal space, and a small amount of fluid lateral to the bladder that was not opacified on the T cystogram (Fig. 5). The finding was interpreted as intraperitoneal rupture with a probable extraperitoneal rupture component. ladder exploration showed a large defect in the bladder dome involving the peritoneal reflection and confirmed the combined intraperitoneal and extraperitoneal rupture. Our investigation also showed that better delineation of the site of the bladder rupture can be achieved with the use of MPR. The site of the bladder rupture was identified in 14 of 18 patients in axial images. In the remaining four cases of intraperitoneal rupture, the sites of rupture were at the bladder domes, which were parallel to the scanning plane of the axial scan. They were only detected by either coronal or sagittal images in MPR. One intraperitoneal bladder rupture with laceration at the dome could be identified on the axial image (Fig. 2). We think this was related to the large size of the laceration because the intraoperative finding of the laceration was 5 cm. Our investigation had several limitations. There was no comparative study to prove the accuracy of T cystography. The results were obtained retrospectively from medical records, and therefore small extraperitoneal bladder ruptures may be missed on T cystography and regarded as negative cases. Similarly, only nine of 18 patients with positive T cystography results had surgical proof of bladder rupture. The exact site of injury of the bladder rupture in the remaining nine patients (two died and the remaining seven were diagnosed as having extraperitoneal rupture) could not be compared because bladder exploration was not performed in these patients. T cystography, however, has several pitfalls that may lead to false-negative results. The Foley catheter tip may abut the small tear site, which may occlude the contrast extravasation. The presence of pelvic hematoma may result in incomplete bladder distention. In addition, the diagnosis of combined intraperitoneal and extraperitoneal rupture may be missed if the rupture site is large because full bladder distention cannot be achieved, and most of the contrast agent is extravasated into the extraperitoneal component but not into the intraperitoneal component [11]. In conclusion, we recommend the use of T cystography in the evaluation of patients with suspected bladder rupture. dditional sagittal and coronal images from MPR may be highly informative for identification of the site of the bladder rupture, particularly in intraperitoneal rupture when the site of perforation is at the bladder dome, which may be difficult to detect on axial images. References 1. ass S. Diagnostic studies in bladder rupture: indication and technique. Urol lin North m 1989; 16: Novelline R, Rhea JT, ell T. Helical T of abdominal trauma. Radiol lin North m 1999; 37: Vaccaro JP, rody JM. T cystography in the evaluation of major bladder trauma. RadioGraphics 2000; 20: Peng MY, Parisky YP, ornwell E, Radin R, ragin S. T cystography versus conventional cystography in evaluation of bladder injury. JR 1999; 173: Lis LL, ohen J. T cystography in the evaluation of bladder trauma. 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