PMC7180743_01
Four-dimensional computed tomographic (4D-CT) images. (A) Sagittal section of computed tomography. (B) Serial four-dimensional computed tomographic images of upper airway during sleep shows glottis closure at a terminal stage of inspiration (blue arrow), subsequent velopharyngeal closure (white arrow head), expansion of the pharyngeal cavity (yellow arrow heads), and succeeding glottis opening with increase of pharyngeal pressure (red arrows).
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F1
Reconstructed 4D-CT images of respiration during sleep (Figures 1A,B; Videos 1, 2) revealed abnormal upper-airway findings compared with the images acquired during awake respiration: glottis closure at the terminal stage of inspiration (normally, the glottis opens during inspiration) (Video 3), subsequent velopharyngeal closure (normally, the velopharyngeal space is open during nasal respiration), and succeeding glottis opening and expansion of pharyngeal pressure, but no other upper airway-obstruction findings, such as glossoptosis, pharyngeal-cavity narrowing, and retrodisplaced epiglottis (Figures 2A-D).
Reconstructed images of four-dimensional computed tomography. (A) Virtual endoscopic image from the subglottic view. The glottis remains open at the terminal stage of inspiration during wakefulness (yellow arrow). (B) Lateral view. The velopharyngeal space remains open at the initial stage of exhalation during wakefulness (white arrow). (C) Virtual endoscopic image from the subglottic view. The glottis closes at the terminal stage of inspiration during sleep (yellow arrow). (D) Lateral view. The soft plate becomes elevated and velopharyngeal closure occurs at the initial stage of exhalation during sleep (white arrow) with expansion of the pharyngeal space (red arrows).
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F2
Reconstructed 4D-CT images of respiration during sleep (Figures 1A,B; Videos 1, 2) revealed abnormal upper-airway findings compared with the images acquired during awake respiration: glottis closure at the terminal stage of inspiration (normally, the glottis opens during inspiration) (Video 3), subsequent velopharyngeal closure (normally, the velopharyngeal space is open during nasal respiration), and succeeding glottis opening and expansion of pharyngeal pressure, but no other upper airway-obstruction findings, such as glossoptosis, pharyngeal-cavity narrowing, and retrodisplaced epiglottis (Figures 2A-D).