Mieke Bus

1 13 application of small caliber instruments, and may, therefore, be difficult to examine by the pathologist. 7 The difficulty to obtain a reliable histopathological diagnosis leads to a high rate of tumour upgrading/upstaging following nephroureterectomy. 7  Optimizing endoscopic visualiza- tion and diagnosis of UTUC is therefore needed. Optical diagnostics are new techniques that have potential to improve the diagnosis of UTUC. Optical diagnostics are based on the interaction of light with tissue. These differences are caused by interactions such as scattering, absorption and fluorescence, all of which are characteristic for certain tissue types. Techniques like NBI, IMAGE1 S™ (formerly known as SPIES) and PDD aim at better visualisation of urothelial tumours and therefore, increased tumour detection rates, while techniques like OCT and CLE aim at providing real time intra-operative information about tumour grade and stage. By detecting differences between the incident and detected light, they can provide information on tissue that is under investigation. Developments in optical diagnostics might reduce the limitations of the current diagnostic methods. Most research on the application of optical diagnostics on urothelium has been done in the field of blad- der cancer. 8,9 One can presume that results on bladder urothelium resemble upper urinary tract urothelium and can be extrapolated to the upper urinary tract. However, the limited space in the upper urinary tract and the difficulty reaching the upper urinary tract creates a whole new spectrum of challenges for the urologists, the technique and result interpreta- tion. The attitude towards the treatment of UTUC has been changed dramatically over the past decades by the acceptance of conservative treatment for low-risk UTUC in patients with a healthy contralateral kidney. Therefore, treatment should be carefully tailored for each indi- vidual patient, based on tumour grade, tumour stage, cytology, multifocality, and tumour size. One of the main challenges in patient selection for conservative treatment of UTUC is to obtain a reliable histopathological diagnosis. Current methods have all their inherent limitations. Recent developments in optical diagnostics showed potential to improve the diagnostic work-up of UTUC. In this thesis we aim to assess the possibilities of optical techniques to optimize diagnosis of upper urinary tract tumours. In the first part of this thesis we explore the application of optical diagnostics in the upper urinary tract. To that end, we determine the need for new diagnostic techniques in the diagnostic work-up of UTUC patients. A survey among (endo)urologists is presented in Chapter 2 . If we understand this need, future studies can be specifically designed to meet the needs for new diagnostic studies. In Chapter 3 we provide an overview of technology, applications and limitations of five recently developed optical diagnostics in the upper uri- nary tract and outline their potential for future applications.