Comparison of Electron Beam Tomography and Multi Detector Computed Tomography for Dynamic Upper Airway Study in Snorers

Lee, Kyu Yup; Lee, Chang Min; Choi, Young Jun; Lee, Yu Jung; Jung, Sang Sik; Kim, Jung Soo

Abstract

Although there are many kinds of modalities to evaluate upper airway obstruction region in snorers and obstructive sleep apnea subjects, we still have many difficulties to evaluate dynamic upper airway mechanics exactly. We investigated whether multi detector CT (MD-CT) is a good tool comparable with electron beam tomography (EBT) for evaluating upper airway dynamics. Each twenty snorers using EBT and MD-CT were included in this study. We evaluated dynamic upper airway mechanics at supine position in awake and asleep state by serial scan image. The space from hard palate to epiglottis tip were divided into four parts; high retropalate (HRP), lower retropalate (LRP), high retroglossal (HRG), lower retroglossal (LRG). We measured minimal cross sectional area (mCSA), maximal cross sectional area (MCSA), and collapsibility index (CI) in each area. Using cross sectional area data also made the simulated diagram of longitudinal view. Maximal stenotic regions of longitudial view were at LRP and HRG area in 18 patients of EBT and 17 patients of MD-CT. mCSA and volume were decreased significantly at asleep state than awake state and CI was increased in both EBT and MD-CT cases. mCSA was smallest at the LRG area and CI was largest at the HRG area and these results were prominent at the asleep state than the awake state. EBT and MD-CT are efficient modalities for dynamic upper airway mechanics due to short scan time. From economical point of view and resolution power, MD-CT is regarded as more efficient modality for evaluating dynamic upper airway mechanics.