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Session: Poster session II
Session starts: Thursday 24 January, 16:00

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Stefan Been ()
Michelle Agenant ()
Wim Koomen ()
Herke Jan Noordmans ()

Abstract:
During transurethral resection of bladder tumours (TURBT) a scope is placed through the urethra, inside the bladder to biopt or resect a lesion. During this procedure the sight of the bladder wall can be impeded by bleeding from that lesion, cloudy urine caused by an infection or blue light during photodynamic diagnosis (PDD). To overcome this problem we built a real-time bladder registration and navigation system, where virtual arrows placed over the endoscope imaging lead the clinician to the primarily marked points of interest. A special tracking device (floil) was developed to make sure that the endoscope could always be seen by the stereo tracking camera, despite interference of the head of the surgeon, legs of the patient and 180º rotation of the endoscope. To assess the accuracy in marking and retrieve previously marked lesions, lab experiments were performed on two developed phantoms: First a rigid box phantom to determine the technical accuracies of the system. It appeared that lesions could be marked with an accuracy of 2-4 mm and could be retrieved in 94% of the cases. Second, a flexible balloon phantom to get an idea about the inaccuracies encountered in a real bladder with its deformaties. The largest shifts occurred, as expected, when lesions were marked at one volume and retrieved at a much bigger or smaller volumes. However, thanks to the field of view of the endoscope, in 70% of the cases the lesions were on the endoscopic video screen after navigation. The next step is the clinical evaluation of this newly developed system, of which inclusion of patients has been started. We hope that this concept of bladder navigation will lead to better reproducibility of cystoscopy. Therefore, lesion should better be recognized resulting in less recurrence and less residual tumours after TURBT. This improves the quality of life and increases the cost effectiveness of the procedure.