Multislice Computed Tomography Assessment of Airway Patency Changes Associated with Mandibular Advancement Appliance Therapy in Supine Patients with Obstructive Sleep Apnea

Figure 2

The measurement variables. (a) Midline and median sagittal cross-sectional images. (b) The five measurement sites of the upper airway on a multiplanar reconstruction (MPR) image. The multislice computed tomography data were imported into OsiriX ver. 3.9, with the window level/window width (WL/WW) set to the CT-bone value of 500/2000 HU. Slice datasets were coordinated as follows: (1) the midline of a midpoint of two straight lines, connecting the uppermost and lowermost ends of the bilateral zygomatic process observed in the coronal section, and a straight vertical line parallel to that midpoint were drawn; (2) the median sagittal cross-sectional image was a sagittal section sliced by the midline, and the median sagittal and axial cross-sections were set to the posterior edge of the maxillary bone (PNS); (3) five distance points were established on the MPR image by verifying on the median sagittal, axial, and coronal cross-sectional images; and (4) the WL/WW was set to the airway component value of -662/724 HU, and the anteroposterior diameter, width, and cross-sectional area at the five distance points were measured on the axial cross-sectional images. Abbreviations: EPS, epiglottic pharyngeal space; IPS, inferior pharyngeal space; MPS, middle pharyngeal space; PPS, palatal pharyngeal space; SPPS, superior posterior pharyngeal space.

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