Grading upper tract urothelial carcinoma with the attenuation coefficient of in-vivo optical coherence tomography

Introduction: With catheter based optical coherence tomography (OCT), high resolution images of the upper urinary tract can be obtained, thereby facilitating the detection of upper tract urothelial carcinomas (UTUC). We hypothesized that the attenuation coefficient of the OCT signal (μ_OCT) is related to the histopathologic grade of the tumor. Objectives: In this study, we aimed to define the μ_OCT cut-off for discriminating high grade and low grade papillary UTUC. Methods: For this post-hoc analysis, data from OCT imaging of papillary UTUC was obtained from patients during ureterorenoscopy. OCT images and raw data were simultaneously analyzed with in-house developed software. The μ_OCT determined in papillary UTUCs and corresponding histopathologic grading from either biopsies or radical resection specimens were compared. Results: Thirty-five papillary UTUC from 35 patients were included. μ_OCT analysis was feasible in all cases. The median μ_OCT was 3.3 mm⁻¹ (IQR 2.7–3.7 mm⁻¹) for low-grade UTUC and 4.9 mm⁻¹ (IQR 4.3–6.1 mm⁻¹) for high-grade UTUC (P = 0.004). ROC analysis yielded a μ_OCT cut-off value of >4.0 mm⁻¹ (AUC = 0.85, P < 0.001) with a sensitivity of 83% and a specificity of 94% for high-grade papillary UTUC. Conclusions: This study proposes a μ_OCT cut-off of 4.0 mm⁻¹ for quantitative grading of UTUC with ureterorenoscopic OCT imaging. The promising diagnostic accuracy calculations justify further studies to validate the proposed cut-off value. Implementation of the software for the μ_OCT analysis in OCT systems may allow for μ_OCT assessment at real time during ureterorenoscopy. Lasers Surg. Med. 51:399–406, 2019.