الفهرس 
Anatomy of the urinary bladderOnly 14 pages are availabe for public view
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Abstract
Bladder carcinoma is the most common tumor among the low urinary tract, accounting for 90% of cancer cases. Several imaging techniques are available to detect bladder neoplasia. However, there is no reliable method for tumor detection, and negative findings require cystoscopy.
Conventional cystoscopy represents the gold standard for diagnosis and local management of bladder carcinoma. However it has many drawbacks such as intense discomfort for the patient and bleeding; furthermore, the high cost, invasivity, and local complications such as infections and mechanical lesions are another well-known drawbacks. Additionally, conventional cystoscopy does not provide information about extravescical extensions of the tumor so .
Recent advances in CT including software developments have led to the use of three dimensional (3D) imaging reconstruction techniques and allow CT urography and virtual endoscopy to be used in daily practice.
The main goal of VC was to develop a non-invasive diagnostic tool that would be easily tolerated by the majority of patients, by producing images similar to those acquired by the conventional endoscopy.
At present virtual cystoscopy based on volumetric data obtained with thin section multislice CT and the use of perspective volume rendering technique, seems to be the most accurate radiological method regarding lesion detection in the urinary bladder.
In our study we tried to investigate the utility of the CT virtual cystoscopy in the detection of the bladder masses, and compared the findings to the gold standard conventional cystoscopy.
The main steps to perform virtual cystoscopy incorporate proper bladder distention with air after draining the residual urine through Foley catheter and scanning the patient in both supine and prone positions.
Our study included fifty patients; 39 of them presented with hematuria and a recent diagnosis of bladder carcinoma, and 11 patients with a history of previous transurethral resection of superficial bladder cancer in their follow up period. They ranged in age from 42 years to 75 years with a mean of 63.12 ; while male to female ratio was 5.25:1.
An excellent overview of the bladder masses was obtained in all cases and the results of virtual cystoscopy and conventional cystoscopy were comparable with excellent sensitivity rates of virtual cystoscopy in detection, localization and morphology description of the bladder lesions at variable sizes. The size of the masses in both groups (n=50) ranged from 2.5 to 90 mm in diameter, including 18 lesions with a diameter of 0.5 cm or less.
The high detection rate of the lesions is mainly attributed to the CT protocol used. Acquisition with thin collimation , creation of MPR images with no artifacts and virtual images of very good quality and excellent anatomic detail facilitated detection of a large number of small tumors with a 16-MDCT scanner.
Our study showed that combined evaluation of axial, MPR and virtual images should be used to increase the performance of the technique, especially in recognition of small tumors with high sensitivity and specificity.
For detection of all lesions (n=62), virtual cystoscopy alone showed sensitivity :98.4%: specificity: 81.81% with two false positive and one false negative in comparison to conventional cystoscopy which detected 61 lesions. While in axial CT (+ MPR) alone the sensitivity :73.8%; specificity: 100% with 7 false negative findings.
Generally speaking virtual cystoscopy has several advantages over conventional cystoscopy specially after the advances of 3D postprocessing techniques:
It is less invasive, less time consuming, requiring less equipment, with fewer patient preparation steps, allowing imaging of the urinary bladder in multiple planes and bypassing any obstruction if present. Also it can be used to evaluate areas of the urinary bladder difficult to assess with cystoscopy, such as the anterior bladder neck and narrow-mouthed diverticula .
On the other hand virtual cystoscopy has still some limitations: It is unable to depict flat lesions or mucosal color changes; does not allow for biopsy; it is unable to identify the origin and nature or depth of invasion of the bladder masses, thus it is alone impractical in staging of the bladder cancer.
In conclusion, virtual CT cystoscopy is a promising technique for tumor and some other bladder lesions, such as diverticula. However it is unlikely to replace conventional cystoscopy.
This minimally invasive method can be of value for screening, primary diagnosis and surveillance of bladder lesions. Virtual CT cystoscopy may be indicated as a clinical routine when conventional cystoscopy is contraindicated or restricted in feasibility and interpretation or there is risk of hemorrhage, perforation, or pain especially in young patients. Also it can be performed on patients request, or if he refuses to undergo the classical conventional cystoscopy.
It may serve as a follow up examination between conventional cystoscopies in bladder cancer patients who are under treatment.
In the future, it may be possible or even advantageous to incorporate into the imaging algorithm for evaluation of bladder lesion through continued development and advancement of hardware and software