Resumen de Development of the paranasal air sinuses in a South African Population utilising three dimensional (3D) reconstructed models
Carmen O. Rennie, Mohamed R. Haffajee, Kapil S. Satyapal
The anatomy of the paranasal air sinuses (PAS) may vary in form and size across populations, and between the sexes and age (Yun et al., 2011). This study aimed to estimate the volumes of the PAS within a South African population using the latest available radiological techniques. Computerized tomography scans (n=480) were reviewed from the Pietermaritzburg and Durban public and private sector hospitals (KwaZulu-Natal, South Africa). The sample consisted of 276 males, 204 females, with age range 1-25 yrs, representing the two main population groups (black African and white). The age range was divided into eight, three-year cohorts viz. 1-3; 4-6; 7-9; 10-12; 13-15; 16-18; 19-21; 22-25. These scans were processed by axial manual segmentation of the air sinuses using a 3D Slicer Program (http://www.slicer.org) to construct a three dimensional (3D) volume model of each PAS bilaterally, with 3840 3D models developed. Maximum (max.) to minimum (min.) volumes for each PAS was as follows for ages: maxillary [max: 31563.3 mm3(R), 32062.3 mm3(L); min: 49.4 mm3(R), 25.4 mm3(L)], frontal [max: 22908.6 mm3(R), 21289.0 mm3(L); min: 50.6 mm3(R), 30.2 mm3(L)], sphenoid [max: 15844.6 mm3 (R), 15433.7 mm3(L); min: 6.3 mm3(R), 7.3 mm3(L)] and ethmoid [max: 14327.5 mm3(R), 13162.0 mm3(L); min: 18.9 mm3(R), 12.6 mm3(L)]. This demonstrated that the maxillary was the largest and the ethmoid the smallest PAS at full growth. At 1-3 years of age, the maxillary air sinus was the largest and the sphenoid air sinus was the smallest. Growth of the air sinuses correlated positively with age. Mean volumes appear to be larger on the left side at full growth, although not statistically significant. Sexual dimorphism was statistically significant for the right frontal sinus. Regarding population groups, notable volume differences were observed in the maxillary sinus bilaterally and left sphenoid sinuses unilaterally. There appeared to be four distinct periods in which the growth of the PAS changed. From ages 1 to 7 years there was a gradual increase with a peak increase from 7 to 9 years, continually increasing in growth rapidly, reaching a maximum by 16 to 18 years of age followed by a plateau thereafter.This study presented data of the PAS of the South African populations using 3D reconstructed models. It is apparent that a study consisting of a large sample of 3D models of the PAS has not been fully reported. In particular, the volume of the ethmoid air sinus from 1 to 25 years of age was documented, which was not fully described. The study confirmed differences in terms of the paranasal air sinuses’ size across populations, particularly the maxillary and sphenoid air sinuses, and sex differences viz. the right frontal air sinus.
