Mieke Bus

78 Chapter 5 OCT Staging In twenty-two patients (83%) staging of visible lesions was concordant with histopathol- ogy. In three patients, staging of the visible lesions was non-diagnostic due to large exo- phytic tumor growth exceeding OCT imaging depth (2 tumours located in ureter and 1 in ureter and pyelum). In one patient, inflammatory lesions were interpreted as invasive tumor lesions, resulting in a false positive diagnosis. In patients with non-invasive tumors, the anatomical layers could be identified underneath the lesions (Figure 5A). In patients with invasive tumors, clear interruption or complete loss of anatomical layers was seen (Figure 5B). In three out of six patients we were able to visually recognize CIS lesions. In patients in whom we were able to identify CIS, a flat broadened urothelial layer with low reflectivity was seen without interruption of the anatomical layers (Figure 5C). Statistical testing resulted in a sensitivity of 100% with a confidence interval of 72-100%, specificity of 92% (62-100%) PPV of 92% (62-100%) and NPV of 100% (72-100%) (Table 3) . Figure 5 A: OCT image of a TaG3 ureter carcinoma. Under visible lesions anatomical structure (arrows) is identified. B: OCT image of a T2G3 lesion. Anatomical structure could no longer be recognized (arrows). C: OCT image of a Carcinoma in Situ (CIS) lesion. Anatomical layers can be identified. A prominent, thickened urothelial layer is recognized (arrows), suggesting CIS. Discussion We confirmed the ability of OCT to visualize, grade and stage low, high-grade and in a lesser extent CIS lesions in the upper urinary tract. OCT as a diagnostic method resulted in a high sensitivity and specificity for UTUC grading and staging. These outcomes confirm results from our previously published pilot study. (4) Although this study was conducted in a small study population, most of the criteria of the STARD initiative were followed, including a power calculation. For this reason, this study is methodologically powerful. (5-7) A consequence of our study design was the exclusion of patients suitable for conserva- tive treatment, resulting in inclusion of only advanced cases of UTUC. Final pathology was chosen as gold standard to compare to OCT results. This resulted in a selection bias.