Evaluation of water content around airway in obstructive sleep apnea patients using peripharyngeal mucosal T2 magnetic resonance imaging

Introduction Obstructive sleep apnea (OSA) is common sleep disorder characterized by repetitive episodes of airway closure which usually occurs in the retropalatal region of the oropharynx. It has been known that upper airway mucosa in OSA patients is described as edematous, but not fully clarified. Objectives This study aimed to investigate and establish magnetic resonance imaging (MRI) parameter to estimate tissue water content at retropalatal level and its relationship with sleep parameters in OSA patients. Methods Forty‐eight subjects with OSA underwent overnight polysomnography and cervical MRI with 1.5‐tesla [mean (SD) age 55 (14) years and apnea‐hypopnea index (AHI) 45.2 (26.1) events/hour, 79.2% male]. On the axial T2‐weighted images from epipharynx to oropharynx, the signal intensities of masseter muscle and peripharyngeal mucosa [T2 mucous‐to‐masseter intensity ratio (T2MMIR)], was used as water content estimation in the retropalatal region. Partial correlation analysis was performed to examine the correlation between T2MMIR and polysomnography parameters. Results We found that there were strong and positive correlations between the T2MMIR and AHI (r = 0.545, P