Three-dimensional evaluation of the posterior airway space: differences in computed tomography and cone beam computed tomography
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Obstructive sleep apnea syndrome (OSAS) becomes increasingly important. For diagnosis and surgery, computed tomography (CT), and cone beam computed tomography (CB-CT) are used equally, although in most of cases, patient positioning differs between supine positioning (CT) and upright seating positioning (CB-CT). We measured volumetric and anatomical changes in the posterior airway space (PAS) between upright and supine positioning in a three-dimensional set up.
Materials and methods
Coherent CT and CB-CT scans of 55 patients were included in the study. Using Brainlab ENT 3.0, image data was superimposed, and three-dimensional models were segmented. PAS height, cross-sectional area, vertical and horizontal position of the mandible and hyoid, and volumetric analyses of the three-dimensional models were measured.
PAS height and cross-sectional area were significantly higher in CB-CT compared to CT scans (p < 0.001). In the vertical dimension, the mandible and hyoid were localized more caudally in CB-CT in contrast to CT scans (p < 0.04; p < 0.001). Three-dimensional evaluation showed a greater volume of the PAS in CB-CT (p < 0.0001). Pearson correlation coefficient showed a correlation between vertical positioning of the mandible and hyoid compared to the positioning of the patient.
Patient positioning during CT and CB-CT has an effect on the location of anatomical structures like the mandible and hyoid and changes the dimensions and volume of the posterior airway space significantly.
The radiological technique used and the positioning of the patient should be taken into account when considering further surgical therapy.
KeywordsComputed tomography Cone beam computed tomography Obstructive sleep apnea syndrome Posterior airway space Volume
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
The study was reviewed and approved by the local ethics committee of University Hospital Aachen (EK266/17).
For this type of study, formal consent was not required. All data were collected anonymously.
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