Virtual cystoscopy in the evaluation of bladder tumors

OBJECTIVE: The objective of this study was to investigate the value of contrast material-filled virtual cystoscopy in the detection of bladder tumors. MATERIALS AND METHODS: Thirty-nine patients who had recent diagnosis or were followed up due to priory history of bladder tumor underwent virtual cystoscopy. After the intravenous injection of contrast medium, the bladder was examined with helical computed tomography (CT) scan. The data were transferred to a workstation for interactive navigation using surface rendering. Two radiologists independently interpreted the axial and virtual images, and discrepancies were resolved by consensus. The results of virtual cystoscopy were compared with the findings of conventional cystoscopy. RESULTS: Forty-nine of 54 bladder lesions detected with conventional cystoscopy in 33 patients were also shown on virtual images. On virtual cystoscopy, three of the seven lesions 5 mm or smaller in diameter could be identified. There were no false-positive findings. The sensitivity of the technique was 96.2% for polypoid tumors and 88.9% for sessile lesions. When axial and virtual images were evaluated together, the sensitivity rate increased to 94.4%. CONCLUSION: Bladder tumors can be diagnosed noninvasively using contrast medium-filled virtual cystoscopy. Evaluation of both the axial and virtual images increases the sensitivity of the technique.     

Bladder tumor detection at virtual cystoscopy

PURPOSE: To investigate the utility of computed tomographic (CT) virtual cystoscopy in the detection of bladder tumors. MATERIALS AND METHODS: Twenty-six patients suspected or known to have bladder neoplasms underwent CT virtual and conventional cystoscopy. The bladder was insufflated with carbon dioxide through a Foley catheter. Helical CT of the bladder was then performed. The data were downloaded to a workstation for interactive intraluminal navigation. Two radiologists blinded to the results of conventional cystoscopy independently reviewed the transverse and virtual images, with consensus readings for cases with discrepant results. RESULTS: Thirty-six (90%) of 40 bladder lesions proved at conventional cystoscopy were detected with a combination of transverse and virtual images. Four (10%) of 40 bladder lesions, all smaller than 5 mm, were undetected. Transverse and virtual images were complementary, since six polypoid lesions smaller than 5 mm depicted on the virtual images were not seen on the transverse images. In contrast, areas of wall thickening were more readily appreciated on transverse images. CT with patients in both supine and prone positions was necessary, since seven (19%) and five (14%) of 36 lesions were seen only on supine and prone images, respectively. CONCLUSION: CT virtual cystoscopy is a promising technique for use in bladder tumor detection of lesions larger than 5 mm. Optimal evaluation requires adequate bladder distention with the patient in both supine and prone positions and interpretation of both transverse and virtual images.     

Virtual cystoscopy of the contrast material-filled bladder in patients with gross hematuria

OBJECTIVE: The objective of this study was to evaluate the usefulness of virtual cystoscopy of the contrast material-filled bladder in evaluating patients with gross hematuria. SUBJECTS AND METHODS: Seventy-three consecutive patients who had gross hematuria and whose upper urinary tracts had a normal appearance on single-detector helical CT scans were prospectively evaluated with virtual cystoscopy. Source CT data for virtual cystoscopy were obtained on a multidetector CT scanner with 1.25-mm slice thickness and transferred to a workstation for interactive navigation using volume rendering. Two radiologists independently interpreted the virtual cystoscopic images, and discrepancies were resolved by consensus. All patients also underwent conventional cystoscopy. We assessed the agreement between the findings on virtual and conventional cystoscopy. Using conventional cystoscopy as the gold standard, we evaluated the usefulness of virtual cystoscopy as an aid in identifying bladder lesions and detecting abnormal bladders. RESULTS: Virtual cystoscopy depicted 60 lesions in the bladders of 43 patients. Fifty-six lesions (in 41 bladders) revealed on virtual cystoscopy were true-positive findings. Four lesions in two bladders with abnormal findings were false-positive. On virtual cystoscopy, the radiologists missed three lesions in two abnormal bladders that were identified on conventional cystoscopy. On virtual cystoscopy, 15 (88%) of 17 lesions smaller than 0.5 cm were identified. The agreement between the findings of virtual and conventional cystoscopy was excellent in the reviewers' identification of bladder lesions (kappa = 0.83) and detection of abnormal bladders (kappa = 0.89). The sensitivity and specificity of virtual cystoscopy were 95% and 87% for identifying bladder lesions and 95% and 93% for detecting abnormal bladders. CONCLUSION: Virtual cystoscopy of the contrast material-filled bladder is useful for the evaluation of the bladder in patients with gross hematuria.     

Virtual CT-pneumocystoscopy: indications, advantages and limitations. Our experience

PURPOSE: The use of CT volume-rendering techniques allows the evaluation of visceral organs without the need for endoscopy. Conventional endoscopic evaluation of the bladder is limited by the invasiveness of the technique and the difficulty exploring the entire bladder. Virtual evaluation of the bladder by three-dimensional CT reconstruction offers potential advantages and can be used in place of endoscopy. This study investigates the sensitivity of virtual CT in assessing lesion of the bladder wall to compare it with that of conventional endoscopy, and outlines the indications, advantages and disadvantages of virtual CT-pneumocystography. MATERIALS AND METHODS: Between September 2001 and May 2002, 21 patients with haematuria and positive cystoscopic findings were studied. After an initial assessment by ultrasound, the patients underwent pelvic CT as a single volumetric scan after preliminary air distension of the bladder by means of 12 F Foley catheter. The images were processed on an independent workstation (Advantage 3.0 GE) running dedicated software for endoluminal navigation. The lesions detected by endoscopy were classified as sessile or pedunculated, and according to size (more or less than 5 mm). Finally, the results obtained at virtual cystoscopy were evaluated by two radiologists blinded to the conventional cystoscopy results. RESULTS: Thirty lesions (24 pedunculated, 6 sessile) were detected at conventional cystoscopy in 16 patients (multiple polyposis in 3 cases). Virtual cystoscopy identified 23 lesions (19 pedunculated and 4 sessile). The undetected lesions were pedunculated <5 mm (5 cases) and sessile (2 cases). One correctly identified pedunculated lesion was associated with a bladder stone. DISCUSSION: Good quality virtual images were obtained in all of the patients. In only one patient with multiple polyposis the quality of the virtual endoscopic evaluation was limited by the patient's intolerance to bladder distension, although identification of the lesions was not compromised. The overall sensitivity was 77%; this was higher for pedunculated lesions (79%) than for sessile lesions (50%). The virtual technique is less invasive and tends to be associated with fewer complications than is conventional cystoscopy. It also demonstrated a good sensitivity for evaluating pedunculated lesions, allowing evaluation of the bladder base and anterior wall, sites that are commonly poorly accessible at conventional cystoscopy. Further advantages of the virtual technique include the possibility of accurately measuring the extent of the lesion and obtaining virtual images even in patients with severe urethral obstruction and active bleeding. The limitations include the inability to obtain tissue for histologic examination or to perform endoscopic resection of pedunculated lesions. The technique is less sensitive than conventional cystoscopy in the detection of sessile lesions or very small polyps (<5 mm). Furthermore, diffuse wall thickening reduces bladder distension thereby preventing optimal evaluation. The most valuable indication appears to be the follow-up of treated wall lesions. CONCLUSIONS: Virtual CT-pneumocystoscopy can replace conventional cystoscopy in cases with pedunculated lesions when there is no need for biopsy, when the lesions are located at the bladder base or when cystoscopic instrumentation cannot be introduced into the bladder due to stenosis. Virtual pneumocystoscopy can also be used in the follow-up of treated polypoid lesions in association with pelvic CT-angiography.     

Comparison of virtual cystoscopy, multiplanar reformation, and source CT images with contrast material-filled bladder for detecting lesions

OBJECTIVE: The objective of our study was to compare the diagnostic accuracy of virtual cystoscopy, multiplanar reformation, and source CT images for lesion detection in the contrast material-filled bladder. SUBJECTS AND METHODS: Two observers independently evaluated 47 patients (28 men and 19 women; mean age +/- SD, 59 +/- 16 years) with virtual cystoscopy, multiplanar reconstruction, and source CT images acquired with contrast material-filled bladder using an MDCT scanner (detector array, 4 x 1.25 mm; beam pitch, 0.75). Agreement between the two observers was evaluated for the three reconstruction methods using kappa statistics. Using the conventional cystoscopic findings as a reference, we compared the results of the three reconstruction techniques both by bladder site and by patient using the McNemar test. RESULTS: The interobserver agreement for the number of positive sites was excellent for virtual cystoscopy (kappa = 0.816), fair for multiplanar reconstruction (kappa = 0.461), and good for source CT images kappa = 0.676). For both observers, the sensitivity for lesion detection by bladder site was significantly greater with virtual cystoscopy (observer 1, 95%; observer 2, 90%) than with multiplanar reconstruction (78% and 60%) and source CT (68% and 65%) images (p < 0.05), whereas the specificity by bladder site and the sensitivity and specificity by patient did not differ with the three methods (p > 0.05). For determining the presence or absence of lesion at each site, virtual cystoscopy was more accurate than multiplanar reconstruction and source CT images for both observers (p < 0.05). CONCLUSION: Virtual cystoscopy is more accurate than multiplanar reconstruction and source CT images for the detection of lesions in the bladder.     

Optimal technique of virtual cystoscopy on single-detector helical CT, and clinical application

The optimal technique of virtual cystoscopy (VC) was determined on single-detector helical CT using a bladder phantom, and its clinical utility was evaluated. A phantom simulating the urinary bladder with 2 dome-shaped polyps (diameters 5 and 10 mm) was constructed. Imaging specifications were as follows: collimation, 3 and 5 mm; pitch 1; reconstruction interval, 1 and 2 mm. The polyps were positioned parallel and perpendicular to the scanning direction. Using these data sets, virtual cystoscopic images were generated by a voxel transmission technique. The threshold values were changed from -950 HU to -250 HU. Three radiologists evaluated visualization of the polyps in terms of proportion and shape on different collimations, threshold values, and location, for each size of polyp. Results indicated that the optimal technique of VC was as follows: collimation 3 mm, pitch 1:1, reconstruction interval 1 mm, and threshold value from -550 HU to -500 HU. VC depicted 13 (81.3%) of 16 lesions on the urinary bladder and prostate diseases noted on conventional cystoscopy using the optimal scanning technique. VC enabled evaluation of the accurate shape of lesions and their relation to adjacent mucosa.     

Detectability of small and flat polyps in MDCT colonography using 2D and 3D imaging tools: results from a phantom study

OBJECTIVE: The objective of this phantom study was to determine the performance of MDCT colonography for the detection of small polyps under ideal imaging conditions and to determine the added value of 3D imaging when used as an adjunct to 2D imaging. MATERIALS AND METHODS: Thirty-six polypoid and 39 flat polyps (44 lesions, 2-5 mm; 31 lesions, 6-8 mm) were placed in three explanted segments of a thoroughly cleaned porcine colon (overall length, 4.5 m) that was distended with air and submerged in a water phantom. MDCT data sets with 4 x 1 mm collimation and 6-mm table feed were reconstructed every 0.7 mm with 1.25-mm effective slice width. The data were reviewed by three radiologists using 2D images in all three projections and with 3D volume-rendered images available as an adjunct to the 2D images. RESULTS: Additional 3D as a problem-solving tool significantly increased the overall sensitivity (96% vs 90%), decreased the total number of false-positive calls (n = 9 vs n = 5), and increased the diagnostic confidence level (p < 0.03) compared with 2D images alone. Small polyps less than or equal to 5 mm (89% vs 95%, p = 0.004) and flat polyps (82% vs 94%, p = 0.001) especially benefited from 3D. Sensitivity was generally higher for polypoid than for flat polyps (99% vs 94%, p = 0.041). CONCLUSION: Under phantom conditions, simulating an ideal clinical setup, MDCT colonography is not limited by spatial resolution and detects polyps less than or equal to 5 mm in size with high sensitivity and specificity. Additional 3D image tools improve diagnostic accuracy and reviewer confidence, especially for the detection of flat and small polyps.     

CT仿真内镜在膀胱病变的临床应用初步研究

目的：评价CT仿真膀胱镜在检测膀胱病变中的作用。材料和方法：30例怀疑膀胱异常病例经膀胱镜和CT仿真膀胱镜检查，采用常规增强CT扫描后30min—1h，膀胱充盈高密度造影剂后，再行膀胱区扫描，层厚3mm，Pitch＝1．5，并在工作站重建；分别由两位有经验的放射科专家独立观察CT仿真膀胱镜结果，并与病理对照。结果：传统膀胱镜检查发现异常病变27例，其中膀胱肿瘤20例，膀胱炎症6例，膀胱憩室3例，神经源性膀胱1例。在CT仿真膀胱镜中发现24例，其中6例膀胱炎症未发现。所有病人均能很好耐受CT仿真膀胱镜检查，没有并发症出现。结论：CT仿真膀胱镜检查是一种比较准确的检测膀胱病变的方法，相对于传统的膀胱镜，它没有任何并发症。     

MR cystography for bladder tumor detection

The purpose of the study was to assess the diagnostic performance of MR cystography with virtual cystoscopic and multiplanar reconstructions for detection of malignant bladder tumors. Thirty-two patients with 43 bladder tumors previously confirmed by cystoscopy (mean size 2.5 cm; 0.4–9.1 cm;) were examined at 1.5 T with a three-dimensional T2-weighted turbo spin echo sequence (TR=2911 ms, TE=500 ms, echo train length 256). Virtual cystoscopic reconstructions (VC) and multiplanar reconstructions (MPR) were obtained and analyzed separately by three radiologists without knowledge of the tumor location. Intraoperative or cystoscopic findings served as standard of reference. Sensitivities and specificities were calculated using a receiver-operating characteristic analysis with five levels of confidence. Area-under-curve values were similar for MPRs (0.952), VC (0.932) and the combination of both methods (0.954). Optimal sensitivity was 92.3% for MPR and 90.7% for VC, respectively, with a specificity of 91.1% for MPR and 90.4% for VC. The combination of MPR and VC resulted in a sensitivity of 90.7% and specificity of 94.0%. MR cystography is a promising, completely non-invasive technique for the detection of bladder lesions with a high diagnostic performance.     

螺旋CT仿真膀胱镜的临床应用价值

目的　探讨螺旋CT仿真膀胱镜 (CTVC)的临床应用价值及限度。方法　 3 6例临床怀疑膀胱病变的患者 ,都经纤维膀胱镜检查 ,并有病理证实。应用螺旋CT采集排泄期的图像做CTVC成像 ,双盲法与轴位、纤维膀胱镜所见对照分析。结果　CTVC能清楚地显示膀胱腔内的各种正常解剖结构 ,8例正常膀胱中 7例可见 11侧输尿管开口 ;CTVC对膀胱腔内病变的部位、大小、数目、形态及侵犯范围的显示均与纤维膀胱镜基本一致 ;膀胱癌的检出率为 94.7% ,2个 <5mm的肿瘤CTVC显示清楚 ,而轴位图像未显示 ;CTVC检测膀胱壁增厚及膀胱外侵犯的状况不如轴位和MPR图像 ,CTVC上假性病灶 1例。结论　CTVC对膀胱病变的显示和诊断是一种较可靠的、非侵袭性的方法 ,但需要膀胱内造影剂充盈良好 ,且必须结合轴位和MPR图像才能对膀胱病变做出全面、准确的评价。     

泌尿道螺旋CT仿真内窥镜的临床应用价值

目的 探讨泌尿道螺旋CT仿真内窥镜的临床应用价值。方法 53例临床泌尿道病变的患者，都经纤维膀胱镜或／和手术证实。应用螺旋CT采集排泄期的图像作CTVE成像，双盲法与轴位，多平面重组（MPR），三维重建（3D）图像及纤维膀胱镜所见对照分析。结果 CTVE能清楚地显示泌尿道腔内的各种正常解剖结构，CTVE对膀胱腔内病变的部位，大小，数目，形态及侵犯范围的显示均与纤维膀胱镜基本一致，膀胱癌的检出率为94．7％，2个＜5mm的肿瘤CTVE显示清楚，而轴位图像未显示，CTVE检测膀胱壁增厚和膀胱外侵犯的状况，显示肾盂，输尿管病变的效果明显不如轴位，MPR及3D图像。结论 CTVE对膀胱病变的显示和诊断是一种较可靠的，非侵袭性的方法，但对肾盂，输尿管病变的诊断价值不大，必须结合轴位和MPR图像才能作出全面，准确的评价。     

64-detector row CT cystography with virtual cystoscopy in the detection of bladder carcinoma: preliminary experience in selected patients

Purpose

This study was conducted to evaluate the role of computed tomography cystography (CTC) and virtual cystoscopy (VC) with 64-slice CT in diagnosing bladder lesions using flexible cystoscopy as the reference standard.

Materials and methods

Twenty-eight patients with suspected bladder cancer and ten patients who had undergone transurethral resection of the bladder were studied by CTC and VC in both the supine and prone positions after distending the bladder with air. The patient population was divided into three groups based on lesion size at flexible cystoscopy. Results of the CT study were compared with those of flexible cystoscopy.

Results

Flexible cystoscopy depicted 88 bladder lesions in the 38 patients examined. Sensitivity and specificity values of CTC and VC alone were constantly lower than those of the combined-approach (group 1: 93.10% and 92.31%; group 2: 100% and 100%; group 3: 100% and 100%, respectively). Receiver operating characteristic (ROC) curve analysis showed that the combined approach decreases the lower dimensional threshold for lesion detection (1.4 mm).

Conclusions

VC and CTC with 64-slice CT are promising diagnostic techniques for bladder cancers measuring 1–5 mm. Further studies on larger patient populations are required to validate our results.     

Diagnostic potential of virtual cystoscopy of the bladder: MRI vs CT. Preliminary report

The aim of the study was to evaluate the diagnostic potential of the half-Fourier acquired single-shot turbo spin echo (HASTE) sequence for MRI cystoscopy compared with CT cystoscopy and the gold standard conventional cystoscopy. The MRI- and CT cystoscopy was performed in 29 patients with bladder tumors documented at cystoscopy and a control group using a 1.5-T unit (6-mm slice thickness) and a helical CT (3-mm collimation, pitch 1) after filling the bladder with air. Axial MRI and CT images were transferred to a workstation for application of virtual cystoscopy and compared with routine cystoscopy. Axial images and virtual cystoscopies were read by three readers for size and location of tumors. Forty-seven tumors were diagnosed at cystoscopy (12<1 cm, 35≥1 cm). The sensitivity for detection of tumors smaller than 1 cm was 88.9% at MRI cystoscopy and 100% for tumors of 1 cm or larger. These results were not statistically different from the other modalities. Three tumors smaller than 1 cm were not detected at CT cystoscopy, four not all identical at MRI cystoscopy. One tumor with a wall thickening was detected on axial CT and MR images and CT cystoscopy by all observers, but only by two at MRI cystoscopy. The MRI cystoscopy is a diagnostic modality with results comparable to conventional and CT cystoscopy. Electronic Publication     

螺旋CT仿真内窥镜对早期诊断膀胱肿瘤价值的探讨

目的:研究螺旋CT仿真内窥镜技术(CTVE)在早期诊断膀胱肿瘤中的价值。方法:通过导尿管抽出尿液后向膀胱内注入气体行螺旋CT扫描,图像传至工作站行三维仿真膀胱镜重建。盲法评价CTVE和横轴位图像显示膀胱内肿瘤结节病变检出数量的差异,以及两种方法提供的信息情况。结果:20例中CTVE发现膀胱肿瘤18例,而轴位像仅发现14例。横断面图像检出26个结节,CTVE检出31个结节,两者有差异(P<0.05)。CTVE的敏感性和阴性预测值均为100％;横断面图像的敏感性和阴性预测值仅为77.8％和33.3％。5个直径≤5mm的结节轴位像均漏诊。结论:CTVE为一种无创检查,无盲区,可准确显示直径≤5mm的膀胱肿瘤;膀胱充气状态螺旋CT横断面图像可准确显示膀胱壁的增厚等异常;两者结合可为膀胱肿瘤的早期发现和合理治疗提供准确信息。     

Detection of flat colorectal polyps at screening CT colonography in comparison with conventional polypoid lesions

Background Although the screening of small, flat polyps is clinically important, the role of CT colonography (CTC) screening in their detection has not been thoroughly investigated. Purpose To evaluate the detection capability and usefulness of CTC in the screening of flat and polypoid lesions by comparing CTC with optic colonoscopy findings as the gold standard. Material and Methods We evaluated the CTC detection capability for flat colorectal polyps with a flat surface and a height not exceeding 3 mm (n = 42) by comparing to conventional polypoid lesions (n = 418) according to the polyp diameter. Four types of reconstruction images including multiplanar reconstruction, volume rendering, virtual gross pathology, and virtual endoscopic images were used for visual analysis. We compared the abilities of the four reconstructions for polyp visualization. Results Detection sensitivity for flat polyps was 31.3%, 44.4%, and 87.5% for lesions measuring 2-3 mm, 4-5 mm, and ≥6 mm, respectively; the corresponding sensitivity for polypoid lesions was 47.6%, 79.0%, and 91.7%. The overall sensitivity for flat lesions (47.6%) was significantly lower than polypoid lesions (64.1%). Virtual endoscopic imaging showed best visualization among the four reconstructions. Colon cancers were detected in eight patients by optic colonoscopy, and CTC detected colon cancers in all eight patients. Conclusion CTC using 64-row multidetector CT is useful for colon cancer screening to detect colorectal polyps while the detection of small, flat lesions is still challenging.     

Virtual cystoscopy of bladder neoplasms. Preliminary experience]

PURPOSE: We investigated the comparative sensitivity of virtual and conventional cystoscopy in patients with urinary bladder cancer. MATERIAL AND METHODS: Twelve patients (8 men and 4 women; mean age: 61 years, range: 49-73) with findings of bladder cancer at conventional cystoscopy were submitted to volumetric spiral CT of the urinary bladder. Before the examination, the urinary bladder was distended with 180-200 mL of air. CT findings were then sent to an independent workstation to generate interactive intraluminal views of the bladder. The findings of virtual cystoscopy were compared with those of conventional cystoscopy in 11 patients and with the findings of transurethral resection after urethrotomy in one patient. All lesions had pathologic confirmation. RESULTS: Eighteen (90%) of 20 masses detected on conventional cystoscopy were visualized with virtual cystoscopy. The latter allowed readers to identify 13 of 13 masses (100%) > 1 cm and only 5 of 7 (71%) < 1 cm; three 4-mm masses were missed. Although only a subjective evaluation of lesion size was possible on conventional cystoscopy, there seemed to be good agreement on mass size and site with both techniques. DISCUSSION: Cystoscopy plays a key role in the diagnosis of urinary bladder carcinoma. However cystoscopy is invasive, has a limited field of view and lacks an objective scale; moreover, it is not indicated in patients with severe urethral strictures or active vesical bleeding. In our study, virtual cystoscopy depicted all the masses > 1 cm, and a lesion in a diverticulum with a small opening. Virtual cystoscopy was also very useful in a patient with urethral stricture (who could no be submitted to conventional cystoscopy) where it showed the lesion before transurethral resection after urethrotomy. The virtual technique could also be complementary to conventional cystoscopy in evaluation of bladder base and anterior bladder neck, as well as for postchemotherapy follow-up. Unfortunately virtual cystoscopy does not allow biopsy of suspicious lesions.     

Flat colorectal lesions in asymptomatic adults: implications for screening with CT virtual colonoscopy

OBJECTIVE: The clinical significance of flat lesions in colorectal cancer screening remains uncertain. The purpose of this study was to investigate the frequency, histology, and virtual colonoscopy detection of flat lesions in an asymptomatic screening population. SUBJECTS AND METHODS: The morphology of all detected polyps was prospectively recorded as flat or polypoid (sessile or pedunculated) in 1,233 consecutive asymptomatic adults who underwent same-day virtual colonoscopy and optical colonoscopy. A flat morphology was defined as a shallow plaquelike broad-based lesion with a height of less than one half of its width. RESULTS: Of 344 polyps of 6 mm or greater confirmed at optical colonoscopy, 17 (4.9%) were labeled as flat at both virtual colonoscopy and optical colonoscopy; 17 (4.9%), at optical colonoscopy only; and 25 (7.3%), at virtual colonoscopy only, yielding 59 total lesions in 52 (4.2%) of 1,233 patients. Twenty-nine (49.2%) of 59 flat lesions were adenomatous, of which four measured 10 mm or greater and one 6- to 9-mm lesion was histologically advanced. None of the 148 diminutive flat lesions (< or = 5 mm) detected at optical colonoscopy was histologically advanced. Virtual colonoscopy prospectively detected 24 (82.8%) of 29 flat adenomas and 47 (80.0%) of all 59 flat lesions 6 mm or greater. In comparison, the sensitivity of virtual colonoscopy for the detection of polypoid adenomas and all polypoid lesions of 6 mm or greater was 86.2% (156/181, p = 0.58) and 81.0% (231/285, p = 0.86), respectively. CONCLUSION: Flat adenomas measuring 6 mm or greater are uncommon in a typical Western screening population, and advanced flat neoplasms are rare. The sensitivity of virtual colonoscopy for detecting flat lesions was similar to that of polypoid lesions. These results indicate that flat lesions are not a significant drawback for virtual colonoscopy screening.     

Virtual CT cystoscopy: color mapping of bladder wall thickness

RATIONALE AND OBJECTIVES: To improve the conspicuity of bladder tumors in a virtual environment, we developed an algorithm for color mapping the thickness of the bladder wall. The purpose of this study was to demonstrate the feasibility of this algorithm as a component of virtual CT cystoscopy. METHODS: Five subjects with a history of superficial transitional-cell carcinoma of the bladder underwent helical CT scanning after insufflation of the bladder with air. Source images were transformed into three-dimensional models, and the thickness of the bladder wall was demarcated by using a new computer algorithm and a fixed color scale. Results were compared with those obtained by conventional cystoscopy. RESULTS: Three tumors, one site of benign wall thickening, and normal wall thickness were correctly identified by using axial source images and virtual cystoscopy with color mapping. CONCLUSIONS: Color mapping of bladder wall thickness is feasible and demonstrates both normal and thickened urothelium. Its value in identification of small or sessile tumors will require further trials.     

CT仿真膀胱镜临床应用价值探讨

目的：总结螺旋CT仿真膀胱内镜（CTVC）临床应用结果，探索其在临床应用中的意义。资料与方法：对临床具备指征的一组患者，在膀胱排空后静脉推注碘对比剂，待膀胱充盈后行膀胱区域的薄层螺旋CT扫描，将采集的数据转至工作站行后期处理。应用三维导航软件（Navigator Smooth)重建仿真内镜图像，供诊断观察。全部病例均有双盲纤维膀胱内镜（FC）对照检查资料，并将两种检查结果部分手术、病理结果作对照分析。结果：本组56例CTVC，其中未见异常7例，FC发现1例为膀胱结石，余6例正常，符合率85．7％（6／7）；CTVC诊断膀胱肿瘤29例，FC及／或手术证实28例，另1例系前列腺肥大，符合率96．5％（28／29）；CTVC诊断良性改变（憩室、结石、囊肿、外压等）20例均与FC相符，符合率100％（20／20）。结论：CTVC在显示膀胱腔内累及膀胱壁的改变方面具有较高的敏感性，不失为一种非侵入性诊断方法，具有较好的临床应用价值。     

CT仿真膀胱镜的临床应用研究

目的 研究CT仿真膀胱镜（CTVC）的检查方法,成像技术,镜下表现及临床应用价值。方法 用螺旋CT对26 例患者膀胱行容积扫描,利用Navigator软件对容积扫描数据进行三维重建,形成仿真膀胱内窥镜（CTVC）的影像,应用Fly Through软件多角度观察膀胱,全部病例均行纤维膀胱镜检查。结果 CTVC诊断膀胱癌13例,其中直径大于1cm10例,直径小于1cm3例,最小者直径5mm,;膀胱憩室2例;输尿管囊肿3例,前列腺增生3例,正常5例,除1例前列腺增生误诊为膀胱癌外,其余与纤维膀胱镜检查结果均符合。结论 CTVC对膀胱肿瘤,膀胱憩室及输尿管囊肿等膀胱疾病的诊断是一种较可靠的非侵入性检查手段。