|Year : 2003 | Volume
| Issue : 1 | Page : 18-22
Virtual cystoscopy - a promising diagnostic technique
C Anand, L Sudhakar, G Sivasankaran, R Jayaganesh, M Ilangovan, N Muthulatha, MG Rajamanickam, R Emmanuel
Department of Urology,Government Royapettah Hospital, Chennai, India
M G Rajamanickam
7, Anandan Street, T.Nagar, Chennai - 600 017
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objectives: To determine the diagnostic performance of virtual cystoscopy in patients with bladder diseases in comparison with conventional cystoscopy.
Methods: Fifteen patients with different bladder pathologies underwent volumetric spiral CT of bladder after filling it with contrast media (GE medical system light speed multislice scanner). The data were transferred to Advantage workstation AW4.0-03 and virtual cystoscopy was performed using the special software (Navigator GE medical system). All the patients later underwent conventional cystoscopy and the findings of both investigations were compared.
Results: Virtual cystoscopy detected all 10 lesions with >5mm size and missed I out of 3 lesions with 5 5mm size. The overall sensitivity was 90%, specificity was 100%, positive predictive value was 100% and negative predictive value was 83.3%. The average time taken per procedure was 8 minutes. No complications of virtual cystoscopy were encountered in our study.
Conclusions: There seems to be good agreement as regards the site and size of lesions in both techniques. In the quest for a non-invasive investigation for assessment of bladder diseases, virtual cystoscopy is a promising technology.
Keywords: Virtual endoscopy, bladder diseases.
|How to cite this article:|
Anand C, Sudhakar L, Sivasankaran G, Jayaganesh R, Ilangovan M, Muthulatha N, Rajamanickam M G, Emmanuel R. Virtual cystoscopy - a promising diagnostic technique. Indian J Urol 2003;20:18-22
|How to cite this URL:|
Anand C, Sudhakar L, Sivasankaran G, Jayaganesh R, Ilangovan M, Muthulatha N, Rajamanickam M G, Emmanuel R. Virtual cystoscopy - a promising diagnostic technique. Indian J Urol [serial online] 2003 [cited 2020 Apr 6];20:18-22. Available from: http://www.indianjurol.com/text.asp?2003/20/1/18/37118
| Introduction|| |
In the science of medicine, there is a continuous search for noninvasive investigations to assess various illnesses.
In this quest virtual endoscopy is a promising technology. 
Cystoscopy plays a key role in the diagnosis of urinary bladder diseases. However, cystoscopy has its limitations. Moreover, it is an invasive investigation.
Recently three-dimensional computer rendering techniques with rapid image acquisition have made virtual reality imaging possible using a post processing technique done by computer software. With commercially available software, virtual reality imaging allows interactive intraluminal navigation through any hollow organs, simulating conventional endoscopy. , This principle has been utilized to examine a number of anatomical areas like gastrointestinal tract, airways, urinary tract and other hollow organs. 
We investigated the usefulness of virtual cystoscopy in the diagnosis of various bladder illnesses and compared it with conventional cystoscopy.
| Patients and Methods|| |
During the study period (June 2001 to December 2001), 15 patients (13 men; 2 women; age range 41-70 years; mean age 56 years) were included in the study. These patients were randomly selected by draw of lots. The inclusion criterion was sonographic or other radiological evidence of bladder diseases. Patients who had undergone any form of endoscopic examination of urinary tract previously were excluded from the study.
After a scout view of pelvis the bladder was filled with diluted meglumine diatrizoate either through the Foley's catheter or suprapubic needle puncture (in 13 and 2 patients respectively). Helical CT scans of bladder were obtained with 5 mm collimation, 5 mm/sec table feed and a 2 mm reconstruction interval using GE medical system light speed multislice scanner. CT cystographic data was reconstructed with perspective volume rendering by a image processing Advantage workstation AW4.0-03. Flying through approach aided by an endoscopic navigation system (Navigator: GE Medical System) was used for image analysis. The virtual cystoscopy was evaluated by a team of urologists and radiologists and all the findings and time taken for each procedure were recorded. Subsequently all patients were subjected for rigid cystoscopy (0°, 30° & 70° lens). The findings were compared.
| Results|| |
Among 15 patients, 10 patients had bladder growth (13 growths; 7x1 and 3x2), two had bladder diverticulum and 1 had radiation cystitis. An incidental enlarged prostate in one patient was picked up by both modalities. In one patient with bladder diverticulum virtual cystoscopy showed the direct entry of ureter into the diverticulum which could not be seen in rigid cystoscopy [Figure - 3]A&B. Two patients with sonographic or urographic suspicion of bladder pathology were found to have essentially normal bladder by both endoscopic studies and one among them was found to have upper tract TCC on further evaluation.
Total number of bladder lesions and mass lesions picked up by both investigations, location, gross appearance, size of mass and average time taken per procedure are given in [Table - 1].
Virtual cystoscopy could diagnose bladder lesions (irrespective of size) with a sensitivity of 90%, specificity of 100%, positive predictive value of 100% and negative predictive value of 83.3%. In patients with growth of >5mm size, sensitivity and negative predictive value was 100%. In case of growths with 5mm or less in size the sensitivity was only 66.6%.
No complications of virtual cystoscopy was noticed in this study.
| Discussion|| |
Virtual endoscopy is an area where modern computer technology and medicine have come together for the benefit of humankind. Since the original article by Vining, there have been several studies about the utility of virtual cystoscopy. ,,,
In this study, we demonstrated that virtual cystoscopy is a feasible technique for evaluation of bladder pathology. The image qualities of virtual cystoscopy were generally good and it was faster than conventional cystoscopy [Table - 1]. The biggest advantage of virtual cystoscopy is that it is noninvasive. It reduces patient discomfort, anxiety and possible complications.  It allows accurate localization of a lesion and the shape and size measured by virtual cystoscopy is well correlated with conventional cystoscopic findings [Table - 1],[Figure - 1]A,B,[Figure - 2]A,B. Moreover, the size of growth is measured objectively in virtual cystoscopy. 
Multiplanar images can be obtained by various radiographic modalities such as helical CT, MRI and ultrasonography. Currently, helical CT is most commonly employed for this purpose. Iodinated contrast media are more beneficial than air or CO 2 as the delineation of tiny bladder growths are better with contrast media. Air may leak from the bladder during the study, especially while changing the position . Leak does not occur with contrast media. In addition, intravenous contrast was used in selected patients with upper tract dilatation. We used fly through approach for image analysis which gave a visual impression nearly same as that of a fibreoptic endoscopic procedure. This familiarity helps the urologists for better interpretation of results rather the other tedious and time consuming image analysis methods such as individual analysis of mathematical divisions of images or visual analysis of the multiplanar 2D images. , Virtual cystoscopy is more flexible and virtual camera can be rotated up to 360°, so that there is no inaccessible area in the bladder and even posterior view of the mass can be seen very well  [Figure - 4]A. Conventional cystoscopy does not give information regarding the depth of infiltration of tumour. In virtual cystoscopy it is possible to assess the depth because we are doing a helical CT. Moreover the wall of hollow organs can be made transparent to reveal relations with extraluminal structures. 
One of the patients in this study was in early postoperative period after total hip replacement and for him virtual cystoscopy was performed for hematuria and we could arrive at a possible diagnosis of radiation cystitis [Figure - 4]B (radiation 2 years back for carcinoma prostate). Cystoscopy which was done later confirmed the features of radiation cystitis. Two patients with bladder growth had associated urethral stricture which needed intervention before conventional cystoscopy. Virtual cystoscopy can therefore overcome physical constraints and can be done in patients who are not candidates for conventional cystoscopy  and patients who can not be placed in lithotomy position.  Virtual endoscopy technique is useful in conditions where conventional cystoscopy is difficult such as to study the anatomy of pouches and neobladders. It may be clinically useful for surgical planning of lower abdominal re-operations in patients with bladder substitutes.  Virtual examination of urethra, ureter and kidney can be performed but the image resolution of these studies are limited at present. 
There are several limitations of virtual cystoscopy. In our study virtual cystoscopy failed to detect a growth which was about 3 mm in size and surrounding carcinoma in situ changes in a patient. The current resolution of spiral CT does not allow reliable and consistent visualisation of small (<5 mm) lesions.  Reducing the slice thickness may improve resolution to a certain extent but increases the radiation dose to the patient. It has been estimated that absorbed radiation may be upto 40% higher for a multislice helical CT examination than for equivalent conventional CT scan.  This is of concern especially when using it as a screening procedure in the follow up of patients with TCC.  Virtual cystoscopy can not provide a histopathological diagnosis.  Ureteric orifices are not clearly visualized in all patients. Another drawback of virtual cystoscopy is that it is more expensive for patients at present and the approximate cost of the software (Navigator GE medical system) is about Rs. 8 Lakhs.
Few limitations of our study are limited number of patients and most of our patients had a previous sonological diagnosis of bladder pathology. However the interpreters of virtual cystoscopy were blinded to patient's history and previous investigation results.
Virtual simulators such as URO Mentor is commercially available and is being used for endourological training. , As virtual dissection and resection is possible proposed surgeries can be practiced in virtual simulators. Surgical margins can be accurately assessed and differential tissue diagnosis can be made based upon spectral or other information contained in the patient specific images and models. Virtual reality techniques will be useful in telesurgery and in robotic surgery in the future. ,,,,
| Conclusions|| |
Virtual cystoscopy is in its infancy. Preliminary results in virtual cystoscopy are promising. Our study proves that virtual cystoscopy is a promising technique for use in detection of bladder lesions larger than 5 mm. Virtual cystoscopy cannot replace conventional cystoscopy in all situations. It can serve better in selected conditions such as patient's refusal of an invasive diagnostic modality, patient unfit for conventional cystoscopy like distal obstruction, presence of active haematuria, patients with bladder substitutions and early postoperative period. It can serve as a complementary examination performed between conventional cystoscopic examination in patients with bladder tumour during follow-up. To determine the clinical value of routine CT virtual cystoscopy in all patients, however, a large prospective study in the general patient population if necessary.
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]
[Table - 1]