Virtual endoscopy of the urinary tract

Abstract

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.

The paranasal sinuses: three-dimensional reconstruction, photo-realistic imaging, and virtual endoscopy

“…Therefore it can be used as an educational tool [13], as well as in diagnosis [17] and preoperative planning [50]. VE could be applicable in the long-term follow-up of patients with paranasal sinuses disease [26]. Nevertheless images were not completely free from artefacts and distortions.…”

“…VE uses very sophisticated technologies such as computer and graphic systems [35]. Actually, this imaging modality was applied on different parts of the human body such as the urinary tract [26], the oesophagus [12], the colon [11,39], and tracheobronchial system [20,34,49]. We have created patient-specific 3D models of the paranasal sinuses to be used by both radiologist and otolaryngologist for VE with using virtual reality modelling language (VRML) technique.…”

Bladder Cancer in 2010: How Far have We Come?

“…38 The advantages of virtual cystoscopy include its minimal invasiveness, the evaluation of the urethral orifice from a cranial view, the visualization of the mucosa within diverticulae, and its use in patients with urethral stricture disease. 40,41 The disadvantages include cost, inability to obtain tissue, low sensitivity to depict flat lesions such as carcinoma in situ (CIS), and increased radiation exposure, specifically with CT cystoscopy. 38,42 CT cystoscopy is performed by insufflating air or carbon dioxide into the bladder; alternatively, bladder distention can be achieved by instilling dilute contrast through a 6-French feeding tube.…”

Designing a Laser - Based System for Locating Kidney Stones in Surgeries through Percutaneous Nephrolithotomy (PCNL)

“…-In 2006, in another research done by Kagadis et al, combining MRI and CT imaging leads to more accurate results in locating the renal pelvis, however, in comparison to PCNL surgery, this technique does not decrease the absorbed dose of radiation (16).…”