Conclusions: The internal nasal valve (INV) angle in Asians is 21.6 degrees +/-4.5 degrees and it is significantly larger than that of Caucasians. The reconstructed CT method has better reproducibility than the endoscopic method in measuring the INV angle.
Objectives: The INV is an area of interest for nasal surgeons due to its functional significance in rhinoplasty and septoplasty. This study was designed to evaluate the size of the INV angle in an Asian population by measuring the angle through reconstructed CT scans and nasal endoscopy.
Patients and methods: Thirty-eight ostiomeatal unit CTs and 24 endoscopic photos of patients who had minimal or no sinonasal problems were analyzed. CT images that had been reconstructed perpendicular to the acoustic axis and endoscopic photos were used to measure the INV angle. Each method was verified as to reproducibility and the angles measured by the two methods were compared.
Results: The INV angle of the Asians measured by CT scan was 21.6 degrees +/-4.5 degrees . This value was significantly larger than that of the Caucasians, which has been reported to be 11.4 degrees +/-2.6 degrees (p<0.001). The INV angle measured endoscopically was 19.3 degrees +/-3.6 degrees . Reproducibility of the reconstructed CT method was good (p<0.001), while the reproducibility of the endoscopic method was poor (p=0.093). The correlation between the two methods was also poor (p=0.107).