Mieke Bus

35 3 Data extraction Full text articles were reviewed for data extraction by two authors (MTJB and MPLP). Study quality of human, in-vivo diagnostic studies was reviewed according to QUADAS standards. (11) IDEAL stage and level of evidence according to the Oxford Center of Medicine for diagnostic tests was subsequently assessed. (9, 10, 12) Ex-vivo and animal studies were not included for quality assessment. In case a single research group published multiple arti- cles on a specific optical diagnostic technique, only the most recent publication was taken into account. Results The literature search rendered in total 37 articles. After undoubling, filtering and applying exclusion criteria, 11 articles remained for analyses on study quality and data extraction (Figure 1). Confocal laser endomicroscopy rendered 1 article, Narrow band imaging ren- dered 1 article, Optical Coherence Tomography rendered 6 articles, Storz Professional Imag- ing Enhancement System (SPIES) rendered 0 articles and Photodynamic Diagnosis rendered 3 articles. In total 8 articles reported on human studies, the other 3 articles were conducted in animals. Quality assessment Of the 11 articles, 4 articles in human in-vivo setting were suitable for quality assessment (Figure 2). These prospective studies all have a 2B level of evidence. However, all studies have been conducted according to the first steps of the IDEAL standards (1-2a), Evaluating by the QUADAS standards to assess the quality of diagnostic accuracy, showed minimal bias of the four studies available for quality assessment. Techniques based on light absorption Narrow Band Imaging Narrow Band Imaging (NBI) Olympus® is an optical image enhancement technique for endo- scopic applications, with demonstrated value in gastroenterology and urology (bladder). (13-15) NBI is based on the principle that the depth of light penetration into the mucosa increases with increasing wavelength and enhances contrast between mucosa and microvascular structures (table 1). By illuminating the tissue with specific wavelengths (blue 415nm and green 540nm), both strongly absorbed by haemoglobin, the vascular structures appear dark brown/green against a pink/white mucosal background. (Figure 3). (13, 16) New digital flexible endoscopes with integrated WL and NBI are already commercially available allowing the application also in the upper urinary tract. Until now, only one report is published on NBI in the upper urinary tract that consisted of 27 patients undergoing URS. Of these 27 patients, only 15 had UTUC. NBI improved tumour detection rate by 22.7% compared with white