Correlation and reliability of cone-beam computed tomography nasopharyngeal volumetric and area measurements as determined by commercial software against nasopharyngoscopy-supported diagnosis of adenoid hypertrophy.

INTRODUCTION: The aim of this study was to evaluate the diagnostic correlation and reliability of Dolphin Imaging fully automated segmentation (Dolphin Imaging and Management Solutions, Chatsworth, Calif) for assessing adenoid hypertrophy. This was investigated through 3 modes: (1) intraobserver and interobserver agreement of repeated airway auto-segmentation procedures, (2) correlation between auto-segmentation measures of volume and minimal cross-sectional airway against nasopharyngoscopy, and (3) optimum diagnostic cutoff thresholds for volume and minimal cross-sectional airway identified and tested with sensitivity and specificity analyses.

METHODS: Cone-beam computed tomography scans of 38 patients with suspected upper airway obstruction were analyzed. Two calibrated evaluators applied a previously validated method to quantify nasopharyngeal minimal cross-sectional airway and volume using Dolphin Imaging. Assessments were compared against grades of obstruction provided by otolaryngologists' diagnoses.

RESULTS: The reliability between the 2 assessments by the same evaluator on the Dolphin automatic segmentation function for volume (ICC, 0.97; 95% CI, 0.95, 0.98) and minimal cross-sectional airway (ICC, 0.84; 95% CI, 0.69, 0.91) was excellent. The interoperator reliability for volume was also excellent (ICC, 0.97; 95% CI, 0.95, 0.98), but only good (ICC, 0.701; 95% CI, 0.44, 0.85) for minimal cross-sectional airway. In contrast, the Spearman rank correlation test demonstrated weak associations between the values of the automatic measurements for both volume (4.9%; ρ = -0.22) and minimal cross-sectional airway (3.7%; ρ = 0.19). Assessments of accuracy via Receiver Operating characteristic analysis, sensitivity, specificity, negative predictive values, positive predictive values, and likelihood ratios demonstrated the poor clinical applicability of volume and minimal cross-sectional airway numbers provided by Dolphin Imaging.

CONCLUSIONS: The evaluators were reliable at manipulating the selected software, achieving consistent volume and minimal cross-sectional airway measurements, However, Dolphin Imaging volumetric and minimal cross-sectional airway measurements did not correlate well with the nasopharyngoscopy-supported reference standard for adenoid hypertrophy assessment. Under these study conditions, volume and minimal cross-sectional airway used to assess localized adenoid hypertrophy with cone-beam computed tomography imaging based on automated measurements may not yield high-quality clinically relevant information about upper airway constriction related to adenoid hypertrophy.