title: Sleep magnetic resonance imaging: dynamic characteristics of the airway during sleep in obstructive sleep apnea syndrome.
abstract: OBJECTIVE
  To determine the dynamic characteristics of airway obstruction in subjects with obstructive sleep apnea (OSA) syndrome.
  
  
  METHODS
  A prospective cohort study of 20 OSA patients and 19 control subjects who underwent real-time magnetic resonance imaging (MRI) evaluation between 2006 and 2008.
  
  
  METHODS
  The dynamics of the upper airway were visualized using real-time MRI (RTHawk system, Stanford, CA) during natural sleep. Respiratory and desaturation events were correlated to polysomnogram results, and anatomic site of obstruction was determined from the real-time MRI sequences. The relation between visually observed airway obstructions and autonomic system changes was quantified and reliability calculated (Cronbach α, Aabel 2009; Gigawiz, Ltd., Tulsa, OK). An automated analysis tool was developed to determine which respiratory event is associated with the longest duration and location of obstruction in the posterior airway space (Matlab 2009; Mathworks, Inc., Natick, MA).
  
  
  RESULTS
  Airway obstructions visualized on Sleep MRI during natural sleep included retropalatal, retroglossal, and combined obstruction. Respiratory events (mean rate of 31.9 per hour per subject) and desaturations (mean rate of 19.4 per hour per subject) temporally coincided with airway obstructive events. Intrarater reliability coefficients ranged from a low of 0.95 to a high of 1.0 for each rater. Inter-rater reliability coefficients ranged from a low of 0.85 to a high of 1.0.
  
  
  CONCLUSIONS
  Sleep MRI is a novel and reliable approach to simultaneously evaluate airway obstructions and respiratory events in real time during natural sleep. Sleep MRI can define the dynamic characteristics of airway obstruction in both surgically naive and postsurgical OSA patients.
authors.affiliation: Division of Sleep Surgery, Department of Otolaryngology, Wilford Hall Medical Center, Lackland Air Force Base, Texas 78236, USA. jose.barrera@us.af.mil
authors.forename: Jose E
authors.initials: JE
authors.lastname: Barrera
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D012890:Sleep / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult