Utility of narrow band imaging in the diagnosis of middle turbinate head edema

Purpose: Middle turbinate head edema has recently been found to have high specificity for diagnosis of inhalant allergy. However, subtle mucosal edema can be difficult to appreciate under white light endoscopy. Narrow band imaging (NBI) has the potential to demonstrate edema by identifying reduced mucosal vascularity and improve sensitivity for the detection of mucosal edema. Narrow band imaging was assessed to determine its utility in objectifying mucosal edema. Meaterials and methods: A cross-sectional diagnostic study was performed on patients with edematous mucosa of the middle turbinate head. Under traditional white light endoscopy, areas of edematous mucosa were identified. Using NBI, these areas were compared to areas of normal mucosa on the middle turbinate head. NBI images of these same areas were then converted to grey scale and a vascularity index was created by pixel analysis and brightness in Fiji Image J software (Wisconsin, US). Results: Thirty-three middle turbinates were assessed (age 42.4 ± 12.5, 42.4% female). NBI discriminated between areas identified under white light endoscopy as edematous and normal (158.2 ± 48.4 v 96.9 ± 32.7 p < 0.01). Receiver operating curve (ROC) analysis suggested a threshold of 115 brightness units to define endoscopically visible edematous mucosa with sensitivity 70% and specificity 79% (ROC AUC, p = 0.85). Conclusions: NBI can differentiate edematous from normal mucosa. The potential for an objective measure of mucosal edema may assist research efforts and may provide a more sensitive tool for subtle mucosal inflammatory changes.