3D Airway in Clefts Figure 2. Graph depicting airway volume in CLP vs. non-CLP. doi:10.1371/journal.pone.0043405.g002 The airway volumes were not significantly different between the cleft and non-cleft groups (P = .07). The cleft group showed an average volume of 18.1 cm3 with a standard deviation of 7 cm3 and the non-cleft group showed an average volume of 15.1 cm3 with a standard deviation of 5.8 cm3 (Fig. 2). The smallest cross sectional areas were not significantly different between the cleft and non-cleft groups (P = .45). The cleft group showed an average cross sectional area of 115.7 mm2 with a standard deviation of 58.5 mm2 and the non-cleft group showed an average of 113.8 mm2 with a standard deviation of 59.2 mm2 (Fig. 3). The location of the smallest cross sectional area for the cleft group was the oropharynx in 17 out of 19 of the cleft cases and 18 of the 19 non-cleft cases while the remaining in both groups was at the junction of the oropharynx and hypopharynx (Fig. 1). The airway length was significantly different between the cleft and non-cleft groups (P = .004). The cleft group had an average length of 60.6 mm with a standard deviation of 8.6 mm and the non-cleft group had an average length of 52.6 mm with a standard deviation of 4.5 mm (Fig. 4 and Table 1). More specifically, the cleft and non cleft groups were assessed based on age. The males with clefts had an average airway length of 62.4 mm with a standard deviation of 8.1 mm and non-cleft males had an average length of 52.9 mm with a standard deviation of 4.1 mm (P = .01). The females with clefts had an average airway length of 57.6 mm with a standard deviation of 9.1 mm and the non-cleft females had an average airway length of 50.8 with a standard deviation of 5.3 mm (P = .20). A linear regression was used to model the relationship between volume and area for both CLP and non-CLP groups. A best-fit line was found on a scatter plot of airway volume and smallest cross sectional area. The r2 value was 0.37 and 0.53 (Fig. 5) for CLP and non-CLP, respectively. The CLP group demonstrated a weaker (less linear) relation between volume and cross-sectional area. In CLP individuals, a greater airway volume did not necessarily correlate to a proportionately larger cross-sectional area. Therefore, it was possible to use a ratio of the cross-sectional area to volume in order to compare the CLP group with the non- Figure 3. Graph depicting smallest cross-sectional area not significantly different in CLP vs. non-CLP. doi:10.1371/journal.pone.0043405.g003 PLOS ONE | www.plosone.org 3 August 2012 | Volume 7 | Issue 8 | e43405