Bladder cancer is the fourth leading cause of cancer in American men, accounting for more than 12,000 deaths annually. It was one of the first malignancies in which carcinogens were recognized as an important factor in its cause. Currently, cigarette smoking is by far the most common cause of bladder cancer, although occupational exposure to arylamines has been implicated in the past. Gross or microscopic hematuria is the most common sign at presentation (Amling. 2001).
The urinary bladder is the commonest site of malignant neoplasia in the genitourinary tract. An early metastatic spread, with a high mortality rate, is the typical course of the disease. There are a few reports regarding the CT features of bladder neoplasia, as advanced-stage, large, broad-based, heterogeneous bladder masses. However, the preoperative characterization of the nature of bladder neoplasm based on the imaging findings is difficult. Differential diagnosis of large-sized, advanced-stage bladder malignancies should include a high-grade urothelial carcinoma, undifferentiated carcinoma, like small cell carcinoma, primary or secondary lymphoma, metastasis from SCC outside the bladder and sarcoma (Kim et al., 2003).
Bladder cancer is a common problem facing urologists worldwide. The gold standard for its diagnosis and follow-up is the direct visualization of the tumor using conventional cystoscopy. Despite having high sensitivity and specificity for detecting bladder cancer, conventional cystoscopy is regarded as an invasive procedure which is associated with several complications. In addition, regular follow-up of patients with bladder cancer is a financial burden on the health system (Mohamed et al., 2008).
Ultrasonography has been proposed as the initial test for detection of bladder carcinomas in patients presenting with hematuria. For ultrasonography, the sensitivity, specificity, positive and negative predictive values were good but not as good as cystoscopy. While the tolerability of cystoscopy is relatively low, it is still superior to ultrasonography in the evaluation of the bladder as a possible source of hematuria (Stamatiou et al., 2009).
Virtual Cystoscopy using Volume Ultrasound is an emerging application used to detect bladder lesions. This technique is useful for diagnosing urinary bladder pathology. Benefits include a more comprehensive understanding of pathology when correlating 2D and volume information, thus providing increased diagnostic confidence. An additional benefit is the reduction of patient discomfort and the cost savings of potentially eliminating the need for an invasive examination. This is especially true when considering follow up cystoscopy after a therapeutic cystoscopy or surgery (Dahiya et al., 2004).
CT urography and virtual endoscopy images are generated from dedicated multislice helical CT data sets and various three-dimensional reconstruction techniques. These imaging techniques can provide external and endoscopic images of the urinary tract and also provide high spatial resolution images helping overcome some of the limitations of intravenous urography and ultrasound. Conventional cystoscopy is the standard method for the detection of urinary bladder neoplasm, but the technique is invasive and uncomfortable. Other drawbacks are the inability to evaluate extravesical pathology and a 5-15% risk of urinary tract infection (Song et al., 2001).
With the progressive development in diagnostic imaging and medical computer software technologies, it was possible to generate virtual reality images to aid the clinician to inspect the interior of the bladder in real time. This technology is considered as a safe test for bladder cancer diagnosis and follow-up, and it is associated with cancer detection rates comparable with conventional cystoscopy. However, it is associated with some drawbacks that limit its use in routine clinical practice at the current time (Mohamed et al., 2008).
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 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 (Kagadis et al., 2006).
One of the important advantages of virtual CT cystoscopy is the minimal invasiveness of the technique. The evaluation of intravesical and extravesical pathology is possible with the same study. Although CT data interpretation was based mainly on the axial images, the combined evaluation of transverse and virtual cystoscopic images has been proved mandatory in CT cystoscopy, since small-sized tumors may be detected only or predominantly on virtual images (Tsampoulas et al., 2008).
In the assessment of recurrent bladder tumors, diagnostic efficiency of virtual cystoscopy carried out by multidetector computed tomography was investigated and compared with the criterion standard of conventional cystoscopy (Mohamed et al., 2008).
Virtual endoscopy 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 (Kagadis et al., 2006).
Virtual CT cystoscopy for now remains a complementary examination. Its main limitations are the inability to provide biopsy tissue specimens for histopathologic examination, something that is possible with conventional cystoscopy, providing a basis for optimal therapeutic planning. Another disadvantage is the difficulty to depict carcinoma in situ and flat lesions or small-sized tumors. The introduction of multidetector CT scanners improved the feasibility of virtual CT cystoscopy in detecting tumors smaller than 5 mm (Arslan et al., 2006).
Use of virtual cystoscopy should be considered in patients who present with hematuria or have histories of bladder carcinoma operation and are for follow-up because of its lesser complication risk and its being a less invasive, easily applied procedure without need of anesthesia (Basak et al., 2009).
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