Diagnostic Accuracy of Narrow Band Imaging in the Identification of Vocal Cord Lesions: A Systematic Review and Meta-Analysis

Background: Vocal cord lesions encompass a wide spectrum of pathology, from benign polyps and nodules to premalignant leukoplakia and invasive squamous cell carcinoma. Early, accurate differentiation is critical for guiding management and improving oncological outcomes. Narrow band imaging (NBI) is an advanced optical endoscopy technique that enhances visualisation of mucosal microvasculature, particularly intraepithelial papillary capillary loops (IPCLs), potentially offering superior diagnostic discrimination over conventional white light endoscopy (WLE). Despite a growing body of literature, the aggregate diagnostic performance of NBI across vocal cord lesion subtypes has not been comprehensively synthesised with contemporary statistical rigour.

Objectives: To determine the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of NBI for identifying malignant and premalignant vocal cord lesions, and to compare NBI performance with WLE.

Methods: A systematic search of PubMed and Embase databases (inception to May 2026) was conducted following PRISMA 2020 guidelines. Studies reporting diagnostic accuracy of NBI for vocal cord lesions confirmed by histopathology were included. Quality was assessed using QUADAS-2. Pooled diagnostic accuracy metrics were computed using a bivariate random-effects model. Heterogeneity was quantified using I² and Cochran Q statistics. Summary receiver operating characteristic (SROC) curves were constructed. Subgroup and meta-regression analyses explored sources of heterogeneity.

Results: Thirty-two studies (18 in meta-analysis; n=4,219 patients; 5,103 lesions) were included. Pooled NBI sensitivity was 0.89 (95% CI: 0.85–0.93) and specificity was 0.92 (95% CI: 0.88–0.95). PLR was 11.26 (95% CI: 7.84–16.18), NLR was 0.12 (95% CI: 0.08–0.17), and DOR was 98.4 (95% CI: 52.6–184.0). The area under the SROC curve (AUC) was 0.96. NBI demonstrated statistically superior sensitivity (p<0.001) and specificity (p<0.001) compared to WLE. Significant heterogeneity was observed for sensitivity (I²=81.3%, p<0.001) but not specificity (I²=47.2%, p=0.09). NBI classification system (Ni vs. ELS), setting (in-office vs. intraoperative), and endoscope type (flexible vs. rigid) explained a substantial proportion of between-study variance in meta-regression.

Conclusion: NBI demonstrates excellent diagnostic accuracy for differentiating malignant and premalignant vocal cord lesions from benign conditions, substantially outperforming WLE. Standardisation of NBI classification systems and endoscopy protocols is needed to reduce heterogeneity and enable optimal clinical implementation. NBI should be considered an integral component of the laryngological diagnostic pathway