Narrow band imaging and bladder cancer: when and how.

Narrow band imaging (NBI) is an optical enhancement technology for endoscopy. NBI works filtering the standard white light in two bandwidths of illumination of 415 nm, blue, and 540 nm, green. As a result, capillaries on mucosal surface appear brown and veins in connective subepithelial layer cyan, enhancing the contrast among epithelial, subepithelial tissue and its vascularisation. Given that it is a filter, it is safe, does not need any kind of instillation and the vision modality can be switched from NBI to white light and vice versa without any limitations of time. NBI-assisted cystoscopy increases the detection rate of urothelial lesions and enhances visibility of tumour margins with respect to standard white light modality, although it does not need a particular learning curve. NBI exploration of the bladder should be avoided during active bleeding because the light absorption would be excessive impeding an optimal vision. Moreover, it should always be employed in combination with standard white light modality to avoid an excess of false-positive findings, particularly during or immediately after topic treatments. It can be used in office to anticipate bladder recurrences and in the operating theatre to perform a complete tumour resection. As a matter of fact, it is able to reduce the recurrence rate and ameliorate bladder cancer management by identifying high-grade cancerous tissue, especially Cis, undetected by the standard white light modality.