The Role of Narrowband Imaging in Laryngeal Cancer

Abstract

Narrowband Imaging (NBI) is an optical imaging modality that enhances and contrasts mucosal microvasculature. By detecting changes in intraepithelial papillary capillary loops (IPCL) as a marker of neoangiogenesis, NBI can detect pre-malignant and malignant mucosal lesions. In 2011, the Ni classification system of NBI based on the morphology of IPCLs was proposed to detect pre-malignant and early malignant laryngeal lesions. This classification system has been reported to be more sensitive than WLE in detecting early laryngeal cancer. This thesis examines the role of NBI in the work-up and diagnosis of pre-malignant and malignant laryngeal lesions. In the first study, the diagnostic accuracy of NBI using the Ni classification in laryngeal cancer is assessed. Ni grading was compared against the gold standard histopathological findings to determine the sensitivity, specificity, positive and negative predictive values of NBI. The second study expands the utility of NBI in the work-up of laryngeal leukoplakia. Leukoplakia limits assessment of IPCLs and has been reported to be a limitation of using NBI. However, recent studies have suggested that NBI can still be applied in laryngeal leukoplakia with superior accuracy compared to WLE. A systematic review and meta-analysis was performed to assess the diagnostic accuracy of NBI in differentiating between low-risk laryngeal leukoplakia (defined as normal epithelium, simple hyperplasia, low and moderate grade dysplasia) and high-risk laryngeal leukoplakia (defined as severe dysplasia, carcinoma and invasive cancer. The third study assesses the inter and intra-observer reliability of NBI in differentiating between benign and malignant disease and making an optical diagnosis. Furthermore, the impact of operator experience on the interpretation of the images is assessed.