title: Evaluation of upper airway collapsibility using real-time MRI.
abstract: To develop and demonstrate a real-time MRI method for assessing upper airway collapsibility in sleep apnea.
  
  
  
  Data were acquired on a clinical 3 Tesla scanner using a radial CAIPIRIHNA sequence with modified golden angle view ordering and reconstructed using parallel imaging and compressed sensing with temporal finite difference sparsity constraint. Segmented airway areas together with synchronized facemask pressure were used to calculate airway compliance and projected closing pressure, Pclose , at four axial locations along the upper airway. This technique was demonstrated in five adolescent obstructive sleep apnea (OSA) patients, three adult OSA patients and four healthy volunteers. Heart rate, oxygen saturation, facemask pressure, and abdominal/chest movements were monitored in real-time during the experiments to determine sleep/wakefulness.
  
  
  
  Student's t-tests showed that both compliance and Pclose were significantly different between healthy controls and OSA patients (P < 0.001). The results also suggested that a narrower airway site does not always correspond to higher collapsibility.
  
  
  
  With the proposed methods, both compliance and Pclose can be calculated and used to quantify airway collapsibility in OSA with an awake scan of 30 min total scan room time. J. Magn. Reson. Imaging 2016;44:158-167.
authors.affiliation: Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.|Alltech Medical Systems America, Solon, Ohio, USA.
authors.forename: Ziyue
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California, USA.
authors.forename: Weiyi
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.
authors.forename: Michael C K
authors.initials: MC
authors.lastname: Khoo
authors.affiliation: Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Sally L
authors.initials: SL
authors.lastname: Davidson Ward
authors.affiliation: Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.|Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California, USA.
authors.forename: Krishna S
authors.initials: KS
authors.lastname: Nayak
mesh_terms: D000293:Adolescent; D000328:Adult; D003199:Computer Systems; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods*; D008297:Male; D010614:Pharynx / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D020181:Sleep Apnea, Obstructive / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: airway collapsibility; airway compliance; real-time MRI; simultaneous multi-slice imaging; sleep apnea; upper airway