Mieke Bus

108 Chapter 7 analysis for the µ OCT of low-grade versus high-grade UTUC yielded an AUC of 0.85 (95% CI 0.69 – 0.95, p<0.001), and a µ OCT value of >4.0 mm -1 was identified as the optimal cut-off to discriminate high-grade from low-grade UTUC. This cut-off resulted in a sensitivity of 83% and a specificity of 94%. Although this adjusted method to calculate µ OCT resulted in a new cut-off value of >4.0 mm -1 , sensitivity and specificity remained compatible to the method used in chapters 4 and 5 of this thesis. Our adjusted method confirmed the ability of OCT to grade and stage low-, high-grade and CIS lesions in the upper urinary tract with a more accurate sensitivity and specificity. Figure 1: screenshot of the in-house developed software for µOCT analysis; A) manual selection of the region of interest from the circular OCT scan (left panel) with coupled selection in the raw amplitude data of the linear scan (right panel); B) determining the µOCT by fitting a single-backscattering OCT model to the averaged A-scans of the selected region of interest (in between black stippled lines).(12) OCT still needs comprehensive investigation before implementation in clinical practice. In order to know the real value of OCT, dedicated in vivo studies as described above should provide further insight in the ability of OCT to differentiate between low-, high-grade and CIS lesions. In addition, specific studies should confirm the diagnostic accuracy including sensitivity, specificity, positive predictive value and negative predictive value. (8) Finally, by comparing OCT with established pre-operative and intra-operative methods like CT-scan,