Comparison Between Mathematical and Software Calculation Methods for the Measurement of the Cross-sectional Area in Upper Airway Imaging

Abstract

ObjectivesThis study aimed to compare the results of a software calculation method (SCM) and the mathematical calculation method (MCM) in measuring the cross-sectional area (CSA) at four different upper airway segments.MethodsThe data from the retrospective chart reviews of patients older than 18 years who had undergone computed tomography (CT) of the neck at our tertiary care center between September 2014 and September 2018 were reviewed. Data of patients who were intubated, tracheostomized, had nasogastric tubes, tumors, craniofacial anomalies, trauma, or any pathology that may affect the normal airway anatomy were excluded. We measured the anteroposterior (APD) and transverse diameter (TD) utilizing the CT software. CSA was calculated using both the mathematical formula (MCM) and software (SCM) at the glottis, proximal subglottis, distal subglottis, and tracheal levels. A paired sample t-test was used to determine the significant difference between SCM and MCM at each level.ResultsThe data of 100 patients (59% female) were reviewed. There was a significant difference between the SCM and MCM at all four levels. The mean differences between the SCM and MCM were -33.63 mm2, -24.20 mm2, 6.04 mm2 (p < 0.001) at the glottis, proximal subglottis, and trachea, respectively. The mean difference at the distal subglottis was -4.08 mm2 (p = 0.01).ConclusionOur study found a significant difference between the SCM and MCM in measuring the CSA of the four airway segments. Theoretically, the SCM is more accurate and precise than MCM in measuring CSA; however, we could not prove the superiority of either method.

Novel and pragmatic exploration of variation in glottic parameters in non-parallel versus parallel vocal cord CT planes with potential reporting pitfalls

“…Glottic lumen is bounded laterally by vocal folds, anteriorly by junctional zone of vocal cords i.e., anterior commissure and posteriorly by posterior commisure between arytenoid cartilages [ 27 , 34 , 35 ]. Measured dimensions of its lumen can vary either due to pathology or various physiological factors including phonation, breath holding, swallowing, demographic characteristics or CT technique [ 9 , 10 , 36 , 37 ]. We have not encountered a single study mentioning all glottic parameters in non-cadaveric sample of CT scan.…”

“…All luminal dimensions are close to our NPVC plane except AP dimension questioning an accuracy of plane selection. They also derived comparison of computation method for CSA analysis from the same data set and preferred software manual method, as used in our study [ 36 ]. Our observation of negative relationship between CSA and VCw is self-explanatory as thick VC reduces lumen size.…”