Target Audience: Sleep medicine physicians and MR physicists who are interested in upper airway imaging. Introduction: The feasibility of a novel real-time 3D MRI (rt3DMRI) of the upper airway has been demonstrated in overweight and obese adolescents who snore [1]. The rt3DMRI covers the entire airway with sub-second resolution, is less affected by head motion than rt2D mid-sagittal MRI [2] without making an abrupt change in acoustic noise and disrupting subject’s natural sleep in a magnet, and is thus capable of reliably identifying the sites of airway obstruction. In this abstract, we investigate the patterns of airway obstruction during central or obstructive sleep apneas in adolescents who underwent both overnight polysomnography and real-time 3D MRI.