The bladder and bladder tumors: imaging with three-dimensional display of helical CT data

Can CT Virtual Cystoscopy Replace Conventional Cystoscopy in Early Detection of Bladder Cancer?

Aim. To correlate findings of conventional cystoscopy with CT virtual cystoscopy (CTVC) in detecting bladder tumors and to evaluate accuracy of virtual cystoscopy in early detection of bladder cancer. Material and Method. From June 2013 to June 2014, 50 patients (46 males, four females) with history and investigations suggestive of urothelial cancer, with mean age 62.76 ± 10.45 years, underwent CTVC by a radiologist as per protocol and subsequently underwent conventional cystoscopy (CPE) the same day or the next day. One urologist and one radiologist, blinded to the findings of conventional cystoscopy, independently interpreted the images, and any discrepant readings were resolved with consensus. Result. CTVC detected 23 out of 25 patients with bladder tumor(s) correctly. Two patients were falsely detected as negative while two were falsely labeled as positive in CTVC. Virtual and conventional cystoscopy were comparable in detection of tumor growth in urinary bladder. The sensitivity, specificity, positive predictive value, and negative predictive value of virtual cystoscopy were 92% each. Conclusion. CTVC correlates closely with the findings of conventional cystoscopy. Bladder should be adequately distended and devoid of urine at the time of procedure. However, more studies are required to define the role of virtual cystoscopy in routine clinical practice.

Hsp74, a potential bladder cancer marker, has direct interaction with keratin 1

Early diagnosis and prognosis monitoring are very important for the survival of patients with bladder cancer. To identify candidate biomarkers of bladder cancer, we used a combination of techniques including 2-DE, co-IP, western blot, LC-MS/MS, and immunohistochemistry. Hsp74 was identified with high expression in bladder cancer. The cellular location of expression products of gene Hsp74 showed that they were distributed into cytoplasm and keratin 1 was found to be associated with Hsp74. The results provide a new idea to understand the molecular basis of bladder cancer progression and pinpoint new potential molecular target for early diagnosis and therapeutic monitoring of bladder cancer.

The Role of Virtual Cystoscopy, after Multidetector Computed Tomography Imaging Reconstruction without the Use of Contrast Medium, in the Diagnosis and Evaluations of Bladder Tumors: Preliminary Study

Introduction. Although conventional cystoscopy is considered to be the gold standard for diagnosis and follow-up of bladder tumors, it remains an invasive and costly procedure. With the advent of the multidetector CT (MDCT) scanners supported by specialized software virtual cystoscopy (VC) is possible. We assess the role of VC in diagnosing and evaluating bladder lesions. Materials and Methods. Between September 2010 and October 2011, 25 consecutive patients with cystoscopically confirmed bladder tumor underwent VC. The radiologists involved in this prospective study were blinded to the exact findings. After draining any residual urine with a catheter, the bladder was retrogradely insufflated with 200–600 cc of air. No intravenous or intravesical contrast was used. MDCT scan was performed in supine and prone positions and three-dimensional reconstruction of the urinary bladder was performed. Results. The examination was well tolerated by all patients with no complications. In total, 43 lesions were detected both with conventional cystoscopy and VC. Tumor size measured by CT ranged from 3 to 80 mm in diameter. The pathological report revealed noninvasive transitional cell carcinomas in all cases. Conclusion. VC has promising results in detecting exophytic bladder lesions. In the future it could be part of the diagnostic algorithm for bladder tumors.

Computed tomography-virtual cystoscopy in the evaluation of a bladder mass: Could it replace standard conventional cystoscopy?

Objective

To determine the role of computed tomography-virtual cystoscopy (CT-VC) in the detection and evaluation of bladder cancer, compared to standard conventional cystoscopy (CC).

Patients and methods

Twenty-five patients with a clinical presentation of a bladder mass(es) were selected from an outpatient urology clinic between May 2011 and August 2012. All patients were then assessed using multi-slice CT of the bladder, CT-VC and CC. The results were then compared amongst axial CT images, multiplanar reconstruction (MPR) images, CT-VC and CC, and compared with the pathological results.

Results

Forty lesions were found at CC in the 25 patients. MPR images had a greater sensitivity for detecting small masses of ⩽5 mm, and for identifying the location of the masses, especially basal (100%), than had axial images. The diagnostic results varied significantly (P = 0.031 and 0.039) between CC and axial images. The difference was slightly significant (P = 0.063) for MPR images and was not significant (P = 0.99) for virtual images.

Conclusions

Compared to CC, CT-VC was much less invasive, but it was not possible to take a biopsy and provide tissue for histopathology, and it could not depict flat lesions or mucosal colour changes. Therefore, CT-VC could be considered for bladder mapping before CC, in the follow-up of patients with superficial transitional cell carcinoma after transurethral resection of the tumour, in combination with urine cytology, and for patients in whom CC is difficult or contraindicated.

Laparoscopic transvesical excision and reconstruction in the management of mid-urethral tape mesh erosion and stones around the bladder neck: initial experiences

Study Type--Prevalence (prospective cohort) Level of Evidence 1b. What's known on the subject? and What does the study add? Managing foreign bodies, including mesh and stones, after anti-incontinence surgery is important because complete removal is necessary to prevent infection and recurrence of stone formation. Traditionally, surgical management of such complications has involved excision using a transurethral approach, with or without a laparoscopic transvesical procedure. The study shows that mesh complications, including exposure and adherent stones, can be successfully treated and a fast recovery can be achieved using transvesical laparoscopic excision and reconstruction. Transvesical laparoscopy is especially suitable for cases that have a restricted visual field with cystoscopy; the technique allows complete removal of mesh/stones and reconstruction with the help of an excellent visual field.

OBJECTIVES

• To evaluate laparoscopic transvesical excision and reconstruction for the management of vesical mesh or stones around the bladder neck as complications of anti-incontinence intervention. • To compare the techniques, outcomes and recurrence rates of laparoscopic transvesical excision and reconstruction with published results from studies using laparoscopic transvesical procedures.

PATIENTS AND METHODS

• We conducted a retrospective review of three patients who underwent laparoscopic transvesical excision and reconstruction for vesical mesh and stones around the bladder neck. • Patients were identified from operating records including recorded video and electronic data records. • We also conducted a literature review of the available evidence on transvesical laparoscopy for lower urinary tract complications of anti-incontinence procedures.

RESULTS

• Between March 2005 and May 2011, three women underwent laparoscopic transvesical excision and reconstruction. All presented with storage symptoms and gross haematuria. The interval between surgery and the diagnosis of presence of a foreign body was 1-3 years. • Two women had previously undergone transobturator tape procedures and one had undergone a retropubic procedure. • Complete excision including the mucosa and muscle layer and reconstruction with intravesical sutures was achieved in all cases. • Storage symptoms were resolved within 3 days and haematuria was not observed. • None of the women had recurrent erosion at follow-up.

CONCLUSIONS

• Laparoscopic transvesical excision and reconstruction is a technically feasible method. • This procedure offers excellent visualization of mesh materials and stones, especially in cases of location near the anterior bladder neck. • In selected patients, laparoscopic transvesical excision and reconstruction is an acceptable technique for first-line treatment of complications of anti-incontinence procedures.

Detection of bladder cancer recurrence with real-time three-dimensional ultrasonography-based virtual cystoscopy

This prospective study evaluated the accuracy of grey-scale two-dimensional (2D) ultrasonography and real-time threedimensional (3D) ultrasonography-based virtual cystoscopy for detecting early recurrence of bladder cancer in previously treated patients (n = 40). Real-time 3D ultrasonography-based virtual cystoscopy images were compared with both 2D ultrasonography and interval conventional cystoscopy pathology results. Ultrasound examinations were performed before routine follow-up with conventional cystoscopy. Overall sensitivity for real-time 3D ultrasonography-based virtual cystoscopy was lower than for 2D ultrasonography, indicating it did not provide additional information. The results of combined (2D and 3D) ultrasonography and conventional cystoscopy differed significantly. Where lesions were detected with combined ultrasonography, the number of previous cystoscopies was lower and the tumour stage was significantly higher at initial diagnosis, compared with cases where no lesions were detected. The results suggest that ultrasonography before cystoscopy can be performed more frequently - or, if no lesions are detected by ultrasonography, the interval between cystoscopies can be prolonged - in patients at high risk of bladder cancer recurrence.

Investigating the relationship between virtual cystoscopy image quality and CT slice thickness

OBJECTIVE

To investigate the effect of reconstruction slice thickness on image quality at CT virtual cystoscopy (VC).

METHODS

Pelvic CT examinations in bladder cancer patients were reconstructed at different slice thicknesses (0.6-5 mm) and intervals, and resulting VC images assessed. Quality indicators were ridging, holes, floaters and dimpling artefacts, tumour definition, and an overall score, ranked 1 (best) to 7 (worst). CT number and standard deviation (SD) for bladder contents and bladder wall were recorded. The mean SD was used as a measure of noise, and the contrast-to-noise ratio (CNR) was calculated as the CT number difference between them divided by the average image noise. The mean CNR across the three levels was used for analysis. Each qualitative image quality measure was compared with CT number, noise and CNR measurements.

RESULTS

Dimpling artefacts increased with thinner slice reconstruction and correlated with increased noise, often resulting in poor tumour definition. The best overall image quality score was seen for VC images reconstructed at 1.2 mm slice thickness, probably because of the competing effects of spatial resolution and CNR.

CONCLUSION

A slice thickness reconstruction <1.2 mm does not provide for better image quality at VC owing to the presence of increased noise.

Virtual cystoscopy: the evaluation of bladder lesions with computed tomographic virtual cystoscopy

PURPOSE

Our objective was to assess the accuracy of computed tomographic virtual cystoscopy (CTVC) in the detection of urinary bladder lesions.

METHODS

Twenty-five patients were examined using CTVC. Bladder scanned using multislice CT at a slice thickness of 1 mm. The data were transferred to a workstation for interactive navigation using surface rendering. Findings obtained from CTVC were compared with results from conventional cystoscopy and with pathological findings.

RESULTS

Thirty-eight lesions were identified. The smallest was 0.2 × 0.3 cm; the largest was 7 × 4.5 cm. Both CTVC and conventional cystoscopy were used. Conventional cystoscopy detected the same number of lesions that were detected by CTVC. On morphological examination, 26 of the lesions were polypoid, 7 were sessile and 5 were bladder wall-thickening. While one of the polypoid lesions was reported as an inverted papilloma, 2 of the 5 lesions that were identified as wall-thickening were malignant and 3 were benign. The sensitivity of using CTVC to identify neoplasias was 100%; the accuracy was 89%.

CONCLUSION

Although the definitive diagnosis of some suspected urinary bladder tumours is only possible with conventional cystoscopy and biopsy, CTVC is a minimally invasive technique which provides beneficial information about urinary bladder lesions.

MDCT Urography: Exploring a new paradigm for imaging of bladder cancer

OBJECTIVE

The purpose of this article is to review the epidemiology, staging, and treatment of bladder cancer; to discuss the role of MDCT urography for the evaluation of patients with known or suspected bladder cancer; and to address the role of MDCT urography in patients who require follow-up imaging after a diagnosis of bladder cancer has been made.

CONCLUSION

MDCT urography now has a large role in the evaluation of patients with known and suspected bladder cancer. However, its precise role has not been established. Because many bladder neoplasms will not be detected by MDCT urography and more research is needed to determine the optimal technique for diagnosing bladder cancer, we think that MDCT urography cannot replace cystoscopy at present.

Detection of bladder tumors with 3-dimensional sonography and virtual sonographic cystoscopy

OBJECTIVE

Bladder tumors are among the most common types of malignant neoplasms of the urinary tract. The purpose of this study was to evaluate the potential value of 3-dimensional (3D) sonography and sonographic cystoscopy in detection of bladder tumors.

METHODS

Thirty-one patients with suspected or known bladder tumors were included this study. All patients underwent 3D sonography and conventional cystoscopy within 15 days. The number, size, location, and morphologic features of the lesions were evaluated on gray scale, 3D virtual, and multiplanar reconstruction images obtained from the patients. The results of 3D sonographic cystoscopy were compared with the findings from conventional cystoscopy, which was considered the reference standard.

RESULTS

Twenty-eight (90.3%) of 31 3D virtual sonographic cystoscopic studies had good or excellent image quality. Conventional cystoscopy revealed 47 lesions in 22 of 28 patients; 3D sonographic virtual cystoscopy showed 41 (87.2%) of 47 lesions. Three-dimensional virtual sonography alone had sensitivity of 96.2%, specificity of 70.6%, a positive predictive value of 93.9%, and a negative predictive value of 80% for tumor detection. The combination of gray scale sonography, multiplanar reconstruction, and 3D virtual sonography had sensitivity of 96.4%, specificity of 88.8%, a positive predictive value of 97.6%, and a negative predictive value of 84.2% for tumor detection.

CONCLUSIONS

Three-dimensional sonography is a promising alternative noninvasive technique for use in detection of bladder tumors, their localization, and perivesical spreading. The location, size, and morphologic features of the tumors shown on 3D sonography agreed well with the findings of conventional cystoscopy.

Detection of bladder tumors with dynamic contrast-enhanced MDCT

OBJECTIVE

In a small pilot study, we assessed whether early-phase dynamic contrast-enhanced MDCT can be used to detect bladder tumors and whether thin reconstruction improves the detection rate.

SUBJECTS AND METHODS

Thirty-six patients (30 with 59 cystoscopy-proven bladder cancers and six with normal bladders) underwent dynamic contrast-enhanced MDCT of the pelvis and abdomen. Images were obtained from the symphysis pubis to the diaphragm 70 seconds after injection of 100 mL of contrast medium. McNemar test was used to compare sensitivity per patient, segment, and tumor and specificity per patient and segment for each of three reconstruction methods: 5-mm sections with no overlap (i.e., 5-mm axial images), 2.5-mm sections with 1.25-mm overlap (i.e., thin-section axial images), and 2.5-mm sections with 1.25-mm overlap and multiplanar reformation (MPR) (i.e., thin-section axial images with MPR).

RESULTS

MDCT with a combination of thin, overlapped sections and MPR depicted all but one of 47 bladder tumors larger than 5 mm but only five of 12 tumors 5 mm or smaller. There were no false-positive findings. Per-tumor sensitivity was significantly better with thin-section images with MPR (90%) and thin-section images alone (86%) than with 5-mm axial images (80%) (p < 0.05). Per-segment sensitivity was significantly better with thin-section images with MPR (95%) and thin-section axial images alone (87%) than with 5-mm axial images (79%) (p < 0.05). Per-patient sensitivity and per-patient and per-segment specificity did not differ with the three methods.

CONCLUSION

Dynamic contrast-enhanced MDCT of the pelvis shows promise for the detection of bladder tumors. Use of thin-section images with MPR and thin-section axial images alone had a significantly better rate of detection of bladder tumors than use of 5-mm axial images.

Virtual Cystoscopy by Intravesical Instillation of Dilute Contrast Medium: Preliminary Experience

PURPOSE

We determined whether virtual cystoscopy based on helical data sets can yield urinary capabilities similar to those achieved by fiber-optic cystoscopy.

MATERIALS AND METHODS

A total of 11 patients with ultrasound detected bladder tumors underwent pelvic CT as a single volumetric scan after preliminary bladder distention with saline mixed with contrast medium using a 6Fr infant feeding tube. Cystoscopy was simulated based on a 3-dimensional helical CT data set in real time. Source raw CT data for virtual cystoscopy were reconstructed and navigation was done in real time using surface rendering navigation software. These images and findings were then compared with conventional cystoscopy findings.

RESULTS

An attenuation gradient of 350 HU between the vesical mucosa and urine was noted. Two of the 14 tumors (11 patients) were missed and each was 0.7 cm. All tumors greater than 0.9 cm were detected. Overall sensitivity was 85.7%. There were no false-positive findings. There was good correlation with tumor location and size. The ureteral orifices and their relationship to the tumor were also well appreciated. Subtle mucosal changes on conventional cystoscopy were not delineated by virtual cystoscopy.

CONCLUSIONS

Our method of instilling dilute contrast medium in the bladder offers an excellent attenuation gradient. The overall sensitivity of tumor detection is better than that reported for intravenous contrast medium and pneumocystoscopy.

Virtual endoscopy of the urinary tract

Technological breakthroughs have advanced the temporal and spatial resolutions of diagnostic imaging, and 3 dimensional (3-D) reconstruction techniques have been introduced into everyday clinical practice. Virtual endoscopy (VE) is a non-invasive technique that amplifies the perception of cross-sectional images in the 3-D space, providing precise spatial relationships of pathological regions and their surrounding structures. A variety of computer algorithms can be used to generate 3-D images, taking advantage of the information inherent in either spiral computed tomography or magnetic resonance imaging (MRI). VE images enable endoluminal navigation through hollow organs, thus simulating conventional endoscopy. Several clinical studies have validated the diagnostic utility of virtual cystoscopy, which has high sensitivity and specificity rates in the detection of bladder tumor. Published experience in the virtual exploration of the renal pelvis, ureter and urethra is encouraging but still scarce. VE is a safe, non-invasive method that could be applied in the long-term follow-up of patients with ureteropelvic junction obstruction, urinary bladder tumors and ureteral and/or urethral strictures. Its principal limitations are the inability to provide biopsy tissue specimens for histopathologic examination and the associated ionizing radiation hazards (unless MRI is used). However, in the case of endoluminal stenosis or obstruction, VE permits virtual endoluminal navigation both cephalad and caudal to the stenotic segment. To conclude, VE provides a less invasive method of evaluating the urinary tract, especially for clinicians who are less familiar with cross-sectional imaging than radiologists.

[Virtual multislice computed tomography cystoscopy for evaluation of urinary bladder lesions]

The introduction of multislice computed tomography (MDCT) with the possibility of acquiring isotropic datasets has been an ideal prerequisite for development of virtual MDCT cystoscopy. Remarkable technical progress regarding post-processing of high-resolution 3D datasets as well as a considerable reduction of the time required for post-processing made it possible to introduce virtual MDCT cystoscopy into the clinical routine. 3D post-processing that often required 7-8 h when virtual endoscopy techniques were first developed can now be performed in less than 5 min after transfer of data to the 3D workstation. With the limitations and contraindications of conventional cystoscopy in mind, virtual MDCT cystoscopy may be seen as a valuable alternative to conventional cystoscopy for evaluation of hematuria.

Three-Dimensional CT Virtual Endoscopy in the Detection of Simulated Tumors in a Novel Phantom Bladder and Ureter Model

BACKGROUND AND PURPOSE

Cystoscopy and ureteroscopy have limitations in the evaluation for urothelial tumors, and both are invasive. We studied the utility of three-dimensional (3D) CT virtual endoscopy in phantom models.

MATERIALS AND METHODS

A phantom pelvis was constructed of Plexiglas, porcine pelvic bones, and processed animal fat and scanned at various table speeds in a four detector-row CT machine for ability to detect "tumors" of Solidwater plastic polymer. Images were reconstructed at slice thicknesses of 2.5 to 5.0 mm and reconstructed in 3D for evaluation by two radiologists with no knowledge of the scanning parameters or tumor location. Similar studies were performed with a ureter model.

RESULTS

With 5-mm slices, the sensitivity for bladder tumors ranged from 67% for 2-mm tumors to 100% for 4-mm tumors, with 12 false-positive findings. The overall sensitivity was 86% with 3.75-mm slices with one false positive, and with 2.5-mm slices, the sensitivity was 93%, again with one false positive. For the ureteral tumors, the overall sensitivities and numbers of false positives were 88.9% and eight with 5.0-mm collimation, 88.9% and four with 3.75-mm collimation, and 100% and three with 2.5-mm collimation. The effective radiation dose for all studies was equivalent to that of a standard abdomen/pelvis scan.

CONCLUSIONS

Although virtual endoscopy traditionally has had difficulty detecting tumors <5 mm, the multidetector-row CT protocols used in this study could detect most lesions smaller than this. The scan also depicts the other tissues of the pelvis, which is valuable for staging. The 3D images were produced using data from the CT urogram parameters standard at our institution.

CT cystography and virtual cystoscopy in the assessment of new and recurrent bladder neoplasms

OBJECTIVE

To determine if CT cystography and virtual cystoscopy have a role in the assessment of neoplasms of the urinary bladder.

MATERIAL AND METHODS

Twenty five adults suspected of having bladder tumours underwent CT cystography. Twenty three had subsequent virtual cystoscopic reconstructions from the axial data. The examinations were reviewed by two radiologists and the findings were correlated with those at conventional cystoscopy.

RESULTS

Seventeen masses larger than 0.5 cm were identified by CT cystography in 16 patients. Two patients had normal CT cystography, but one had small recurrent neoplasms on conventional examination. Seven patients had nodular mucosal irregularities which were subsequently shown to be neoplastic in three. Accuracy for diagnosis of neoplasm in all patients was 88%.

CONCLUSION

CT cystography is very accurate at identifying masses larger than 0.5 cm and can show mucosal abnormalities as small as 2 mm. It is minimally invasive and can be diagnostic when conventional cystoscopy is inconclusive. It can indicate appropriate areas for assessment and biopsy at conventional examination. Virtual cystoscopy gave comparable views to conventional cystoscopy, but did not add diagnostic information. It is not likely to replace conventional cystoscopy, but may be helpful in occasional circumstances where the latter is inconclusive, or can not be performed.

Computed Tomographic Virtual Cystoscopy for the Detection of Urinary Bladder Neoplasms

OBJECTIVE

To evaluate the role of computed tomographic virtual cystoscopy (CTVC) in the detection of bladder neoplasms and to compare CTVC at conventional and reduced milliAmperes-second (mAs) settings.

METHODS

Twenty-four patients with known bladder neoplasms from previous conventional cystoscopy were examined with CTVC. The urinary bladder was insufflated with room air and helical CT data were obtained. Virtual images were created using volume rendering algorithms. In eight patients we used both regular (240) and reduced (70) mAs values. The lesions were recorded on transverse tomographic slices and virtual images and compared with conventional cystoscopy, operative and pathology results.

RESULTS

All bladder lesions (30) seen on conventional cystoscopy were demonstrated with CTVC. Two lesions detected on imaging studies and subsequently found at operation were not seen on conventional cystoscopy. In a third case of a neobladder, conventional cystoscopy was impossible due to neoplastic involvement of the penis. In all cases the lesions were equally conspicuous with conventional and low mAs values.

CONCLUSIONS

Computed tomographic virtual cystoscopy is a minimally invasive technique that can provide comprehensive information about urinary bladder tumors. Furthermore, low mAs studies are equally effective for the examination of such patients.

Virtual cystoscopy from computed tomography: a pilot study

OBJECTIVE

To assess the feasibility of virtual cystoscopy reconstructed from helical computed tomography (CT) obtained using an intravenous contrast agent, and to correlate the findings with flexible (FC) and rigid cystoscopy (RC) in patients with bladder tumours.

PATIENTS AND METHODS

Eighteen patients (16 men and two women, mean age 72 years, range 59-80) with haematuria and found to have a bladder tumour on FC were included in a pilot study. Contrast-enhanced helical CT scans were taken and based on these datasets, virtual cystoscopy (VC) images were reconstructed by a radiologist unaware of the findings at cystoscopy. All patients had RC and a biopsy taken. The VC images were compared with the findings from FC and RC.

RESULTS

At FC, VC and RC, 32, 34 and 36 lesions were identified, respectively; 33 (92%) of the abnormal lesions at RC were correctly identified at VC. At VC, all lesions of >4 mm were identified but only one of three <4 mm was seen. There were two false-positive finding at VC; VC correctly identified 17 (94%) of 18 abnormal bladders. Only 25% of the ureteric orifices were seen. Carcinoma in situ and urethral tumours were not visualized.

CONCLUSION

CT-based VC has a high sensitivity for detecting bladder lesions and is comparable with FC; it may have a potential role as a single imaging tool for haematuria. Further larger studies are required to assess its clinical role.

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.

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.

Ureteroscopes: flexible, rigid, and semirigid

Since its introduction, the ureteroscope has undergone significant improvements. Using the currently available rigid, semirigid, and flexible ureteroscopes and working instruments, urologists can diagnose and treat lesions throughout the upper urinary tract. Over the past 25 years, the ureteroscope in combination with shock wave lithotripsy has transformed the diagnosis and treatment of more than 90% of upper urinary tract pathology from an open to an endourologic procedure. With endoscope manufacturers continually incorporating new technology into their ureteroscopes, future models will undoubtedly provide better optics, increased durability, and improved capabilities, resulting in greater success when urologists perform endoscopic forays into the upper urinary tract.

Bladder imaging using multidetector row computed tomography, volume rendering, and magnetic resonance imaging

Both multidetector row computed tomography (MDCT) and magnetic resonance imaging (MRI) are used to evaluate the bladder noninvasively. MDCT offers fast imaging with near-isotropic data sets optimized for three-dimensional imaging, including the latest software for volume rendering. MRI provides distinctive soft tissue contrast resolution and can perform dynamic imaging without radiation exposure. This article discusses the techniques and protocols of each modality with case illustrations of their application in a range of bladder pathologies to show their respective distinct advantages and limitations.

MR imaging of the bladder

MR imaging of the bladder can now be routinely and easily performed with consistent quality. The latest techniques provide high-resolution images of the soft tissue contrast and the ability to perform dynamic contrast imaging and functional pelvic floor studies. MR imaging fits in as a complimentary tool to cystoscopy and to conventional pelvic floor dynamic studies and can provide a unique imaging perspective of the bladder. It is important, however, to remain cognizant of the limitations of its use in tumor detection and discrimination.

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.

Functional reconstruction and minimally invasive techniques

Recent years have seen notable advances in imaging technologies. Three-dimensional computer-rendered techniques with rapid image acquisition have led to the development of virtual reality imaging. Virtual reality imaging allows interactive intraluminal navigation through any hollow viscus, simulating conventional endoscopy. This technique of virtual endoscopy has been applied to many organs, including the urinary tract. Virtual reality endoscopy is beginning to challenge the gold standard of conventional endoscopic evaluation. Recent advances in laparoscopic surgery are largely attributable to technological improvements in imaging equipment. Laparoscopic ultrasound has become a common adjunct in laparoscopic surgery. In particular, advances in video cameras and digital imaging technology have decreased the steep learning curve associated with laparoscopic procedures. Telerobotic systems offer several advantages to laparoscopic surgery, such as all six degrees of freedom, dexterity enhancement, tremor filtering, and stereovision. In addition, technological breakthroughs allow many procedures to evolve from open operations involving lengthy hospital stays to imaging-guided minimally invasive procedures performed on an outpatient basis. Finally, Internet-based imaging is changing the way in which urology services are delivered, by allowing rapid communication between remote locations.

Tumor detection by virtual cystoscopy with color mapping of bladder wall thickness

PURPOSE

We determine the value of color mapping of bladder wall thickness for detection of tumor as a component of virtual cystoscopy.

MATERIALS AND METHODS

A total of 31 subjects with hematuria and/or a history of bladder tumor underwent helical computerized tomography of the pelvis after distention of the bladder with air. Three-dimensional (D) models were constructed, and thickness of the wall was color mapped according to a fixed and validated mm. scale. Axial source images and 3-D models were reviewed and graded for the presence of wall thickening. A comparison was made with findings on conventional cystoscopy in 31 patients and pathological specimen in 13.

RESULTS

Compared with conventional cystoscopy, the analysis of axial image yielded a sensitivity of 0.80, specificity 0.90, positive predictive value 0.80 and negative predictive value 0.90 for the presence of tumor. Examination of color mapped 3-D renderings resulted in 0.83, 0.36, 0.42 and 0.71, respectively.

CONCLUSIONS

Thin axial computerized tomography of the air distended bladder shows promise as a potential screening tool for bladder cancer. The low specificity of color mapped 3-D renderings makes the technique inappropriate for screening. It may valuable for guiding urologists to additional suspicious sites in a patient with a known tumor.

Virtual endoscopy in urology

Recent years have seen notable advances in virtual reality technology and increased interest in potential medical applications. Computed tomography and magnetic resonance imaging data sets, historically viewed as axial images, may now be used to construct a virtual reality endoscopic image, and navigator software systems allow the operator to 'fly' through the urinary tract. Technological evolution has improved the quality of reconstruction, as this is dependent on the software and data set, allowing virtual reality to begin to challenge endoscopic evaluation. This review describes the evolution of virtual reality in urology and the milestones of its current clinical use. Applications may become widespread in the diagnostic evaluation of common urological symptoms, the planning of surgery and the training of future urologists.

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.

Thin-section helical computed tomography of the bladder: initial clinical experience with virtual reality imaging

OBJECTIVES

To evaluate the application of virtual reality imaging of the bladder (virtual cystoscopy) in the detection of bladder masses.

METHODS

Six patients (mean age 61 years, range 43 to 75) with hematuria and positive findings on conventional cystoscopy were studied by means of thin-section helical computed tomography of the air-distended bladder. Using volume-rendering algorithms, interactive intraluminal views of the bladder mucosa were generated (virtual cystoscopy). Results of virtual cystoscopy were compared with those of conventional cystoscopy in each case.

RESULTS

Twenty-six (100%) of 26 masses (mean size 1.7 cm, range 0.3 to 6), detected on conventional cystoscopy, were visualized on virtual cystoscopy. Twelve of 26 masses measured less than 1 cm in maximum diameter. All masses were pathologically proven transitional cell carcinomas. Virtual cystoscopy was well tolerated by all patients, and no complications occurred.

CONCLUSIONS

Our results indicate that virtual cystoscopy is an accurate technique for detection of intrinsic bladder masses. It may represent a radiologic adjunct to conventional cystoscopy for initial evaluation of patients with hematuria and for surveillance of patients after bladder tumor resection.