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Genitourinary Imaging |
1 From the Department of Radiology, Asan Medical Center, University of Ulsan, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea (S.B.P., J.K.K., H.J.L., K.S.C.); and Department of Radiology, National Cancer Center, Goyang, South Korea (H.J.C.). Received June 18, 2006; revision requested August 21; revision received November 7; accepted December 18; final version accepted April 9, 2007. Address correspondence to J.K.K. (e-mail: rialto{at}amc.seoul.kr).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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Materials and Methods: The study was approved by the institutional review board for human investigation, and informed consent was obtained from all patients. This study included 118 patients (91 male, 27 female; age range, 15–87 years; mean age ± standard deviation, 62 years ± 14) who underwent portal venous phase multi–detector row CT (scanning delay, 70 seconds; section thickness, 2 mm) and conventional cystoscopy because of painless gross hematuria or recurrent microscopic hematuria. Two reviewers with different experience levels independently evaluated the bladder for lesions at CT in a prospective fashion. The 
statistic was used to determine the per lesion and per patient agreement between the two reviewers and between the CT and cystoscopic findings. The sensitivity and specificity of multi–detector row CT for bladder lesion detection were analyzed for numbers of lesions and for numbers of patients.
Results: Multi–detector row CT showed excellent per lesion ( = 0.839) and per patient ( = 0.881) agreement between the two reviewers. Respective per lesion and per patient agreement between the CT and cystoscopic findings was also excellent in the first ( = 0.866 and = 0.881) and second ( = 0.802 and = 0.863) reviewers. The sensitivity and specificity of multi–detector row CT were 89%–92% and 88%–97%, respectively, in the per lesion analysis and 95% and 91%–93%, respectively, in the per patient analysis for both reviewers. All statistical parameters of diagnostic accuracy were similar between the two reviewers (P > .05).
Conclusion: Portal venous phase multi–detector row CT can provide high accuracy and reader agreement for bladder lesion detection in patients with painless gross hematuria and recurrent microscopic hematuria; these results indicate that multi–detector row CT can be used as the initial bladder examination in such patients.
© RSNA, 2007
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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In patients at high risk for bladder lesions, conventional cystoscopy has been used as the primary examination. However, this examination has drawbacks, including patient discomfort, equipment requirements, and relatively high cost. In addition, conventional cystoscopic examination can be used to evaluate only mucosal lesions but not the muscular layer or surrounding structures (2–6).
Multi–detector row computed tomography (CT) is an accurate examination for bladder lesion detection. Results of several studies show that CT has satisfactory accuracy for bladder lesion detection (3,7–13); authors of a recent study (7) reported the sensitivity and positive predictive value of multi–detector row CT to be 97% and 95%, respectively.
Multi–detector row CT has advantages over conventional cystoscopy, such as the higher level of patient tolerance for CT and the ability to allow evaluation of the entire urinary tract and surrounding structures (14–17). Therefore, if multi–detector row CT could provide accuracy and reliability comparable to those of conventional cystoscopy, it would be beneficial for use as a primary bladder examination to provide a guideline for establishing the ensuing diagnostic and therapeutic strategies. Previous studies seem to be limited in proving the usefulness of multi–detector row CT as a primary bladder examination because they retrospectively evaluated patients with bladder cancer already diagnosed (3,9,10). Moreover, because the detection of bladder lesions may vary according to the observer's experience level, the reliability of multi–detector row CT also should be evaluated. Thus, the purpose of our study was to prospectively determine the accuracy of portal venous phase multi–detector row helical CT for bladder lesion evaluation in patients with hematuria by using cystoscopy as the reference standard.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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Patients
Between December 2004 and June 2005, 471 patients underwent CT owing to single or multiple episodes of painless gross hematuria or recurrent microscopic hematuria that had occurred more than three times in 1 month. All CT examinations were performed according to a dedicated scanning protocol.
Of the 471 patients, 31 who underwent conventional cystoscopy before CT were enrolled in our study. Three of these 31 patients were excluded because they had undergone transurethral resection for bladder tumor before the CT examination. Consequently, the remaining 28 patients were enrolled in our study.
In the other 440 patients who underwent the CT examination first, conventional cystoscopy was performed except in patients who: (a) had urolithiasis and normal bladder at multi–detector row CT; (b) had renal parenchymal tumors other than urothelial tumors but normal bladder at multi–detector row CT; (c) had normal bladder at multi–detector row CT and clinical or laboratory signs suggestive of renal parenchymal disease; or (d) had a contraindication for conventional cystoscopy, such as bacteriuria, acute cystitis, urethritis, prostatitis, or obstructive prostatic hypertrophy with normal upper urinary tract at multi–detector row CT. According to these criteria, conventional cystoscopy was performed after CT in 90 patients who were enrolled in our study. Consequently, 118 patients (91 male, 27 female; age range, 15–87 years; mean age ± standard deviation, 62 years ± 14) were included in the final study group (Fig 1).
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Conventional Cystoscopy
Conventional cystoscopy was performed by four staff urologists in our institution (Asan Medical Center) who had 10–12 years of experience in cystoscopy. In patients who underwent CT before conventional cystoscopy, urologists were aware of CT results. Bladder lesions were considered present when conventional cystoscopy revealed papillary or sessile lesions from the bladder wall, color change on the bladder mucosa, or ulcerative lesions. In each patient with positive cystoscopic findings, we recorded the location, maximum diameter, and number of bladder lesions.
CT Examination
All CT data were obtained by using a 16-section CT scanner (SOMATOM Sensation 16; Siemens Medical Systems, Erlangen, Germany). Patients were instructed not to void for at least hours before the examination to obtain adequate bladder distension. All patients received 600–900 mL of 2% barium sulfate suspension (E-Z CAT; E-Z-Em, Westbury, NY) orally 1 hour before CT scanning.
The CT protocol of our institution for evaluating patients with hematuria includes unenhanced scanning, corticomedullary phase scanning, portal venous phase scanning for the bladder, and early excretory phase scanning. During unenhanced scanning, adequate bladder distension was monitored by a radiologist (H.J.L.) with 3 years of experience in pelvic CT; adequate bladder distension was indicated when the bladder was spherical and had a minimum diameter greater than 8 cm. After the unenhanced CT images were obtained, iopromide (Ultravist 300; Schering, Berlin, Germany) or iopamidol (Iopamiro 300; Bracco, Milan, Italy) was administered intravenously into an antecubital vein by using a power injector at a dose of 2 mL per kilogram of body weight at a rate of 3 mL/sec to a maximum of 160 mL. Portal venous phase CT for the bladder covered the entire bladder at the 70-second scanning delay, which was determined on the basis of the data from our previous study, which indicated the optimal scanning delay for bladder tumor detection (7).
The CT parameters for bladder scanning were a beam pitch of 3, an x-ray tube voltage of 120 kV, a tube current of 130–150 mAs, a gantry rotation speed of 0.5 second, a beam collimation of 16 x 0.75 mm, a table feed per rotation of 12.0 mm per rotation, an effective section thickness of 2 mm, and a reconstruction interval of 2 mm.
Image Analysis
All CT images were interpreted for patient care. However, to eliminate any possible bias that awareness of the upper urinary tract findings might affect the bladder evaluation, the presence of a bladder lesion was determined by using only bladder CT images for the purposes of our study. Bladder CT images were saved separately and were displayed on a picture archiving and communication system (Petavision; Asan Medical Center, Seoul, South Korea). Two genitourinary radiologists, including an experienced reviewer (J.K.K.) and a less-experienced reviewer (S.B.P.), both of whom were unaware of any patient information, the cystoscopic findings, and the CT findings of the upper urinary tract, independently evaluated the bladder CT images. The first reviewer (experienced reviewer) was a staff radiologist who had worked for 7 years in the genitourinary division, whereas the second reviewer (less-experienced reviewer) was a radiology fellow who had worked for 4 months in the genitourinary division at the start of our study. We differentiated observer performance according to experience by restricting the time spent on CT image interpretation to 3 minutes per patient.
Bladder lesions were considered present when the CT images revealed hyperenhanced lesions that protruded into the bladder lumen or hyperenhanced wall thickening in comparison with the rest of the bladder wall. In each patient, the presence or absence of a bladder lesion was recorded independently by the two reviewers. In patients with positive CT findings, the location and number of bladder lesions were also independently recorded. For the location of the bladder lesion, we performed lesion-by-lesion correlation between portal venous phase CT and cystoscopy.
Statistical Analysis
The weighted statistic was used to evaluate interobserver agreement between the two reviewers with regard to identifying bladder lesions by using both per lesion and per patient analysis.
The results of the CT image interpretation and the conventional cystoscopic findings were also compared for the two reviewers by using the weighted statistic; their agreement was also evaluated by using both per lesion and per patient methods. A weighted value of less than 0.20 was considered poor; 0.21–0.40, fair; 0.41–0.60, moderate; 0.61–0.80, good; and 0.81–1.00, excellent.
By using the conventional cystoscopic findings as a standard of reference, we analyzed the sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of portal venous phase multi–detector row CT for bladder lesion detection for each reviewer; all statistical parameters were evaluated by using both per lesion and per patient methods. Then each statistical parameter was compared for the two reviewers by using the McNemar test after adjusting for the clustering effect (18).
All statistical analyses were performed by using statistical software (SPSS, version 12.0.0; SPSS, Chicago, IL), and significance was indicated when the P value was less than .05.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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The final diagnosis of these bladder lesions was transitional cell carcinoma in 96 lesions, cystitis in seven lesions, and metastasis from gastric cancer in one lesion; three of 96 transitional cell carcinomas were carcinoma in situ. All cases of transitional cell carcinoma and metastasis were histologically confirmed by means of transurethral biopsy. Six of seven cases of cystitis were histologically confirmed by means of transurethral biopsy, and the remaining case was confirmed by means of visual inspection at conventional cystoscopy.
Agreement between CT and Cystoscopic Findings and between Reviewers
Per lesion analysis.—Agreement between CT image interpretation and cystoscopic findings was noted in 108 (92%) of the 118 patients by the first reviewer and in 103 (87%) of the 118 patients by the second reviewer (Table 1). The agreement between CT image interpretation and cystoscopic findings was excellent for both the first ( = 0.866 ± 0.041) and second ( = 0.802 ± 0.047) reviewers. The two reviewers agreed on the number of lesions in 106 (90%) of the 118 patients, so the interobserver agreement was excellent ( = 0.839 ± 0.043) (Fig 2).
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= 0.881 ± 0.043 for the first reviewer and = 0.863 ± 0.047 for the second reviewer). The interobserver agreement for the presence of bladder lesions in each patient was noted in 111 (94%) of the 118 patients, thereby indicating excellent agreement ( = 0.881 ± 0.043).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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value was 0.863–0.881 for both reviewers. In addition, the per patient negative predictive value, which indicates the risk of missing a disease and thereby causing delayed diagnosis or treatment, was 94% for both reviewers. These data suggest that portal venous phase multi–detector row CT offers high accuracy for bladder lesion detection.
In terms of reader agreement for bladder lesion detection, in our study the agreement between the two reviewers with different experience level was excellent; the weighted value was 0.839 in per lesion analysis and 0.881 in the per patient analysis.
A major criticism of portal venous phase multi–detector row CT is its undeniable limitation for detecting small bladder lesions, as noted in previous studies (7–10). The results of our study were also unsatisfactory from the perspective that the sensitivity of multi–detector row CT was 80%–83% in detecting lesions less than 10 mm in diameter.
There are benefits to using multi–detector row CT as the initial bladder examination. First, multi–detector row CT can be used to evaluate both the upper and lower urinary tracts in one session (14–16,19). Second, performing multi–detector row CT before conventional cystoscopy or transurethral biopsy can improve the local staging of bladder cancer because multi–detector row CT does not induce tissue edema and perivesical changes that can mimic perivesical tumor extension.
There are disadvantages of using multi–detector row CT compared with conventional cystoscopy. First, patients with impaired renal function cannot receive contrast material. Second, in patients with metal artifacts such as a metallic prosthesis in the pelvis as noted in our study, multi–detector row CT may be limited in bladder lesion detection. Third, in patients with previous transurethral resection or anticancer drug instillation, procedure-related inflammation may interfere with interpretation of CT images, thereby leading to the false-positive diagnosis of lesions (7). Last, a bladder lesion adjacent to the prostate may be mistaken for the prostate, as occurred once in this series.
We believe our study has a number of positive features. First, the criteria of patient enrollment in our study were close to the actual indications for conventional cystoscopy in daily practice. Our study included patients with painless gross hematuria or recurrent microscopic hematuria, whereas most previous studies included patients who had already had bladder cancer diagnosed. Second, because our portal venous phase multi–detector row CT images were interpreted independently by two reviewers with different levels of clinical experience, we minimized a possible bias related to their different levels of experience. Third, our study was performed in a prospective fashion, whereas most previous studies were performed in a retrospective fashion. Last, our study included 118 patients, whereas most previous studies included 40 or fewer patients.
There are, however, limitations to our study. First, although portal venous phase multi–detector row CT and conventional cystoscopy were performed prospectively, the timing of each examination was not strictly controlled because we performed the examinations according to scheduling availability—in some patients, as many as 29 days lapsed between multi–detector row CT and cystoscopy. Second, there might have been a training effect for the less-experienced reviewer during the 7 months of the study. Third, there might have been a mismatch for counting the number of bladder lesions in patients with multiple small lesions crowded into a particular focal area. Last, the scanning delay in our study was fixed in all patients by referring to the results of a previous study with four-detector row CT (7). Because the maximum contrast material enhancement time of a bladder lesion may vary according to various factors, such as a patient's cardiovascular function and the injection rate of the contrast material, our scanning delay may have been suboptimal in some patients. Moreover, the maximum contrast material enhancement time of cystitis may be different from that of bladder cancer. This limitation may reduce the diagnostic performance.
There may be an argument about administration of oral contrast material in our CT protocol because oral administration can make assessment of stones in the calyces, ureters, and bladder more difficult. Our routine CT urography protocol is aimed at evaluating all possible disease in the urinary tract. Consequently, to achieve accurate interpretation of lymph node status or other retroperitoneal changes, our routine CT urography protocol requires oral administration of contrast material.
There may be a concern about the reader agreement on the degree of contrast enhancement in the bladder lesion. This study would have been more robust if readers had estimated the degree of contrast enhancement and extracted the threshold level for determining the presence of bladder lesions. However, we did not quantify the amount of the contrast enhancement in each bladder lesion for two reasons. First, it was impossible to estimate the degree of contrast enhancement in small or flat lesions because the 2-mm effective section thickness of our CT protocol could not obviate partial volume averaging in lesions with a height or a diameter less than 4 mm. Second, before beginning our study, observers reached agreement on abnormal contrast enhancement by means of visual inspection in several cases.
There may be a criticism about a possible patient selection bias because only 25% (118 of 471) of patients who underwent multi–detector row CT underwent cystoscopy. Our study was prospectively designed, but patients in whom our urologist could not find a reasonable indication for conventional cystoscopy did not undergo it. We believe that patients who had a possibility of a bladder lesion underwent conventional cystoscopy in our study, so the effect of patient selection bias was not severe.
In our study, we analyzed data only in patients with gross hematuria or recurrent microscopic hematuria. Therefore, our results may not be fully applicable to patients with transient or episodic microscopic hematuria.
In conclusion, portal venous phase multi–detector row CT can provide high accuracy and reader agreement for bladder lesion detection in patients with painless gross hematuria and recurrent microscopic hematuria. We believe portal venous phase multi–detector row CT can be used as the initial bladder examination in such patients.
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ADVANCE IN KNOWLEDGE |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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= 0.802–0.881 in two reviewers at both per lesion and per patient analysis) for bladder lesion detection. |
IMPLICATION FOR PATIENT CARE |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Author contributions:Guarantor of integrity of entire study, J.K.K.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, S.B.P., J.K.K., H.J.L., K.S.C.; clinical studies, S.B.P., J.K.K., K.S.C.; experimental studies, J.K.K.; statistical analysis, J.K.K.; and manuscript editing, all authors
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References |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONADVANCE IN KNOWLEDGEIMPLICATION FOR PATIENT CAREReferences |
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 N Bharwani, N J Stephens, and S D Heenan Imaging of bladder cancer Imaging, June 1, 2008; 20(2): 97 - 111. [Abstract] [Full Text] [PDF]
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