목적: Continuous positive airway pressure (CPAP) is superior to site-specific therapies for obstructive sleep apnea (OSA) including the oral appliances and surgeries with respect to treatment outcomes. One of the main reasons for failure of site-specific therapies might be the absence of a real-time monitoring technique that can detect the upper airway occlusion during sleep. The electrical impedance tomography (EIT) is a non-invasive imaging technique which is useful for long-term monitoring such as evaluation of lung ventilation in the critical care unit. Our goal was to ascertain whether EIT can differentiate the upper airway changes. 방법:Ten healthy subjects (7 males, age 25.7 ± 3.5 yr, body mass index 24.3 ± 4.9 kg/m2) with no history of witnessed apnea underwent an MRI and EIT on the upper airway area. An elastic mask which contained sixteen small electrodes was applied along the lower face, which reflected the retrolingual space of the upper airway. The swallowing maneuver was used to simulate upper airway occlusion. Impedance images were obtained while normal respiration (open airway) and swallowing (closed airway) using the KHU Mark2.5 EIT system. 결과:In all subjects, the closure of the upper airway was successfully visualized in EIT images with reference to MR images. For some subjects, furthermore, the shape of the upper airway in EIT images was well correlated with that in MR images. For other subjects, however, the shape of the airway in EIT was deformed by artifacts. The shape of the airway in MRI and EIT was matched in seven (70%) of ten subjects. 결론:We could estimate the upper airway patency using EIT in healthy subjects. With respect to detection of the shape of airway, however, the accuracy of EIT was equivocal. To establish the EIT as a real-time monitoring device for the upper airway occlusion in OSA patients, further improvement of EIT technique such as noise cancelation and further case-control human studies with larger number of subjects may be needed.