Narrow Band Imaging in the Evaluation of Upper Tract Urothelial Cancer

Upper urinary tract urothelial carcinomas (UTUC) tend to be present at higher age and are more often high grade with over 60% of UTUCs found to be invasive at diagnosis. In addition, concurrent bladder cancer, bladder recurrence, and contralateral UTUC can further complicate the disease course. Radical nephroureterectomy (RNU) is considered the gold standard treatment for UTUC although conservative management with kidney-sparing surgery is considered an acceptable alternative for low-risk cases. Considering the natural history of UTUC, its potentially aggressive clinical course, and accordingly, the rigorous recommendations for follow-up, there is a strong rationale applying advanced technological techniques in order to optimize cancer detection and treatment. Narrow band imaging (NBI) is an optical image enhancement technology introduced in the early 2000s. NBI uses optical filters for RGB (Red, Green, and Blue) sequential illumination and narrows its bandwidth of the spectral transmittance. The reconstructed images created are different from each of the three channels (R, G, and B) and correspond to different layers of the mucosa. The role of NBI in cystoscopy and bladder cancer was subject to several publications in the past decade, showing higher detection rate in several clinical scenarios. This chapter will cover the role for NBI in the context of urothelial cancer, focusing on upper urinary tract cancer.