Mieke Bus

70 Chapter 5 The protocol included a diagnostic URS including biopsies and OCT during the same oper- ative procedure. OCT measurement was only performed in case of visible lesions or strong suspicion for CIS (e.g. positive cytology and negative bladder biopsies). Patients not suitable for conservative therapy were subsequently planned for radical nephroureterectomy or seg- mental ureterectomy. This latter group was selected to compare OCT staging and grading with histopathology of the resected specimen. OCT results were not taken into account for clinical decision making Diagnostic URS and biopsies Diagnostic URS was performed at our operating theatre by two experienced urologists, using semi-rigid and flexible ureterorenoscopes (Karl Storz semi-rigid 9.5Fr, Karl Storz Flex XC, Olympus URF-V). Biopsies were taken after OCT measurement from visible lesions or at random in case of CIS suspicion, using cup biopsy forceps (Piranha®, 3Fr Boston Scientific) or basket biopsy instrument (zero tip 1.9Fr nitinol basket, Boston Scientific). Biopsies were graded low- or high-grade according to theWHO classification of 2004. (8) In addition, tumor invasion was determined if the biopsy contained underlying tissue layers. OCT measurements A commercially available C7-XR tm Intravascular Imaging System interfaced to a single-use C7 Dragonfly tm 2.7Fr (0.9 mm) Intravascular Imaging Probe (St. Jude Medical, St. Paul, Minne- sota, USA) was used. It scans a longitudinal trajectory of 54 mm in approximately 5.4 seconds, producing a 540-frame dataset at 20 µm axial resolution. Amira (Visage Imaging GmbH, Berlin, Germany) was used for 3D visualization. The OCT probe was introduced through the working channel of the ureterorenoscope resulting in simultaneous co-registered URS and OCT. Probe position was ensured by X-ray and endoscopic imaging. OCT imaging was performed at locations with macroscopic presence of tumor or suspected lesions. In case of CIS suspicion OCT imaging was performed at planned biopsy sites. OCT images were analysed after surgery and the urologist performing URS was not informed on the outcome of the OCT images. Histopathological diagnosis of resection specimens and biopsies Standard pathological report of nephroureterectomy specimen was considered reference standard. Nephroureterectomy specimens were examined at the pathology department according to standard protocol. The pathologist was blinded for OCT diagnosis and not blinded for biopsy diagnosis.