title: Real-time multislice MRI during continuous positive airway pressure reveals upper airway response to pressure change.
abstract: To determine if a real-time magnetic resonance imaging (RT-MRI) method during continuous positive airway pressure (CPAP) can be used to measure neuromuscular reflex and/or passive collapsibility of the upper airway in individual obstructive sleep apnea (OSA) subjects.
  
  
  
  We conducted experiments on four adolescents with OSA and three healthy controls, during natural sleep and during wakefulness. Data were acquired on a clinical 3T scanner using simultaneous multislice (SMS) RT-MRI during CPAP. CPAP pressure level was alternated between therapeutic and subtherapeutic levels. Segmented airway area changes in response to rapid CPAP pressure drop and restoration were used to estimate 1) upper airway loop gain (UALG), and 2) anatomical risk factors, including fluctuation of airway area (FAA).
  
  
  
  FAA significantly differed between OSA patients (2-4× larger) and healthy controls (Student's t-test, P < 0.05). UALG and FAA measurements indicate that neuromuscular reflex and passive collapsibility varied among the OSA patients, suggesting the presence of different OSA phenotypes. Measurements had high intrasubject reproducibility (intraclass correlation coefficient r > 0.7).
  
  
  
  SMS RT-MRI during CPAP can reproducibly identify physiological traits and anatomical risk factors that are valuable in the assessment of OSA. This technique can potentially locate the most collapsible airway sites. Both UALG and FAA possess large variation among OSA patients.
  
  
  
  1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1400-1408.
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: Children's Hospital Los Angeles, Los Angeles, California, USA.|Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Gillett
authors.affiliation: Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.
authors.forename: Michael C K
authors.initials: MCK
authors.lastname: Khoo
authors.affiliation: Children's Hospital Los Angeles, Los Angeles, California, USA.|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: 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; D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D045422:Continuous Positive Airway Pressure; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007830:Larynx / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009765:Obesity / Q000150:complications* / Q000000981:diagnostic imaging*; D010614:Pharynx / Q000503:physiopathology; D010641:Phenotype; D015203:Reproducibility of Results; D012307:Risk Factors; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000000981:diagnostic imaging*; D012894:Sleep Stages; D014851:Wakefulness; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: real-time MRI; simultaneous multislice; sleep apnea; upper airway