Volumetric imaging: a potential tool to stage upper tract urothelial carcinoma

Purpose: To investigate whether volumetric imaging of tumor vasculature can be used to phenotypically characterize advanced upper tract urothelial carcinoma, and if this technique can distinguish aggressive invasive tumors from non-aggressive superficial ones. Methods: In a pilot study, two TaG1 and two T3G3 formalin-fixed paraffin-embedded (FFPE) tumor samples were examined using the DIPCO pipeline (Tanaka et al. in Nature Biomed Eng 1(10):796–806. https://doi.org/10.1038/s41551-017-0139-0, 2017). Briefly, punch biopsies of FFPE tumors were deparaffinized, cleared, immunolabeled with the vessel marker CD34 and imaged with a light-sheet microscope. Thereafter, the three-dimensional (3D) vasculature of the tumors was analyzed and characterized using a specialized image processing software. Results: We found that T3G3 tumors had increased CD34 density kurtosis and skewness compared to TaG1 tumors. This suggests that analysis of the 3D vasculature can distinguish between high-grade invasive and low-grade superficial tumors. Conclusions: Volumetric imaging of tumor samples may represent novel methodology that can complement conventional histopathology. Volumetric imaging enabled us to differentiate between invasive and non-invasive upper tract urothelial carcinoma. The method is of particular interest in diagnostic work-up of patients with upper tract urothelial carcinoma as previous findings indicate that volumetric imaging of vascular patterns could be used to differentiate superficial and invasive urothelial carcinoma, irrespective of if the tumor sample was deep or superficial. However, further and more extensive studies are required before this method can be applied clinically.