Korean J Orthod.  2013 Aug;43(4):160-167. 10.4041/kjod.2013.43.4.160.

Three-dimensional evaluation of the relationship between nasopharyngeal airway shape and adenoid size in children

• Oh KM
• Kim MA
• Youn JK
• Cho HJ
• Park YH

• KMID: 2272251
• DOI: http://doi.org/10.4041/kjod.2013.43.4.160

Abstract

OBJECTIVE
To evaluate the shapes and sizes of nasopharyngeal airways by using cone-beam computed tomography and to assess the relationship between nasopharyngeal airway shape and adenoid hypertrophy in children.
METHODS
Linear and cross-sectional measurements on frontal and sagittal cross-sections containing the most enlarged adenoids and nasopharyngeal airway volumes were obtained from cone-beam computed tomography scans of 64 healthy children (11.0 +/- 1.8 years), and the interrelationships of these measurements were evaluated.
RESULTS
On the basis of frontal section images, the subjects' nasopharyngeal airways were divided into the following 2 types: the broad and long type and the narrow and flat type. The nasopharyngeal airway sizes and volumes were smaller in subjects with narrow and flat airways than in those with broad and long airways (p < 0.01). Children who showed high adenoid-nasopharyngeal ratios on sagittal imaging, indicating moderate to severe adenoid hypertrophy, had the narrow and flat type nasopharyngeal airway (p < 0.01).
CONCLUSIONS
Cone-beam computed tomography is a clinically simple, reliable, and noninvasive tool that can simultaneously visualize the entire structure and a cross section of the nasopharyngeal airway and help in measurement of adenoid size as well as airway volume in children with adenoid hypertrophy.

Keyword

Cone-beam computed tomography; Nasopharyngeal airway; Adenoid hypertrophy; Adenoid-nasopharyngeal ratio

MeSH Terms

Adenoids
Child
Cone-Beam Computed Tomography
Humans
Hypertrophy

Figure

• 

  Figure 1 Three-dimensional cone-beam computed tomography images were reoriented, based on the Frankfurt (FH) plane (the FH plane is passing through the right porion [Po] and the left and right orbitales [Or]) and the anterior nasal spine (ANS) used in this study. The FH plane was defined as the standard horizontal plane. The midsagittal plane is perpendicular to the FH plane and includes the ANS. A frontal plane, including the right and left orbitales, is also perpendicular to the FH plane and the sagittal plane. A, Frontal view of a skull. B, Sagittal view of a skull.

• 

  Figure 2 Three-dimensional (3D) measurements of the nasopharyngeal airway on the adenoid plane in this study. A, The nasopharyngeal airway on the midsagittal view. The most enlarged adenoid was tangential; the nasopharyngeal airway's narrowest part is identified as Ad-En; and the nasopharyngeal airway is shown as the yellow area. B, The cross-sectional image of the nasopharyngeal airway in the frontal plane, in which the most enlarged adenoid was included (adenoid plane). C, The volumetric image of the skeletal and internal soft tissues. D, The volumetric image of the pharyngeal airway; the nasopharyngeal airway is shown within the boundary indicated by the green line. E, 3D image of the nasopharyngeal airway in the sagittal view of Figure 2D. F, 3D image of the nasopharyngeal airway in the superolateral view of Figure 2D. G, 3D image of the nasopharyngeal airway in the frontal view of Figure 2D. CAD, Convex adenoid distance; PNS, posterior nasal spine; NA, nasopharyngeal airway; A, the distance between the outermost point of convexity of adenoid shadow and sphenobasiocciput; N, the distance between sphenobasiocciput and posterior end of the hard palate.

• 

  Figure 3 Dendrogram of the 2 nasopharyngeal airway cross-sectional shapes in the adenoid plane by a cluster analysis; the broad and thick (BT)-shaped airway group and the narrow and flat (NF)-shaped airway group. In our study, 52 of the 64 (81.2%) subjects belonged to the BT group, and 12 of the 64 (18.8%) subjects belonged to the NF group.

• 

  Figure 4 Examples of the 2 types of nasopharyngeal airway shapes. Preadolescents who have left-to-right enlarged adenoids on the adenoid plane were more likely to show the narrow and flat (NF) shaped airways to a significant degree and have more flat superior borders and relatively small nasopharyngeal airway spaces; their nasopharyngeal airways demonstrated shorter distances from the superior to inferior borders of their nasopharyngeal airways on the adenoid plane. A, Relatively large nasopharyngeal airway in the sagittal plane. B, Broad and thick type nasopharyngeal airway. C, Relatively small nasopharyngeal airway in the sagittal plane. D, NF type nasopharyngeal airway.

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