Mieke Bus

4 59 Figure 3: Attenuation data of grade 2 & 3 lesions. A) Example of individual depth profiles of a grade 2 (blue) and a grade 3 (red) lesion showing the difference in OCT signal attenuation over depth expressed by the differences in slope. Boxplot for individual µoct values in grade 2 (n=29) and grade 3 (n=13) lesions. For all individual OCT measurements on grading, the median (interquartile range) µoct is 1.97 mm-1 (1.57-2.30) in grade 2 lesions and 3.52 mm-1 (2.74-3.94) (p-value <0.001) in grade 3 lesions. For all patients, no reliable µ oct could be obtained from normal appearing urothelium or CIS due to the small thickness of the urothelium (around 50 µm). Three exemplary cases, illustrative for OCT of the ureter and the three types of UTUC com- monly seen in urological practice, are described in detail below (Figure 4-6). Case 1 – The patient was diagnosed since 2006 with recurrent multifocal TaG1-2 urothe- lial carcinoma of the bladder and right ureter. Follow-up URS showed multiple papillary lesions in the right, proximal, mid and distal ureter. Intra-operative OCT images showed the basement membrane as a thin dark line and protrusions into the lumen of multiple lesions. The protrusion is presented with a shadowing effect due to attenuation of light in the papillary tissue. Since the basement membrane is still present as a thin dark line below these lesions, the OCT diagnosis suggests a non-invasive tumor (Figure 4A). In normal appearing OCT images, the anatomical layers of the ureter could be identified (Figure 4B). Average µ oct for lesions seen in the OCT images was 2.3 ± 0.3 mm -1 . Because of a high recurrence rate in the upper tract on the right side, and since the left ureter showed no defects, a right-sided nephroure- terectomy was performed. Pathology showed multiple TaG1-2 tumors in the proximal, mid and distal ureter. In 3D OCT rendering, suspected tumor regions were manually segmented based on the visibility of the basement membrane below the tumors (Figure 4C). Case 2 – The patient was referred with persistent abnormal selective cytology from the right ureter, suspicious for high-grade urothelial carcinoma. Intra-operative OCT was performed during diagnostic URS on the right side and showed the basement membrane as a thin dark