Laryngeal tumor volume measurements determined with CT: A study on intra- and interobserver variability

Abstract

Purpose : To investigate the intra- and interobserver variability of computed tomography-based volume measurements of laryngeal tumors. Methods and Materials : The volume of 13 laryngeal tumors was repeatedly measured by five independent observers in four different sessions, using the summation-of-areas technique. Mean tumor volume and its standard deviation were calculated for each tumor. Statistical analysis was dome with analysis of variance, Spearman rank correlation, and linear regression. Results : Both the effect of the observers ( p < 0.0001) and the effect of the session ( p < 0.01) on tumor volume was statistically significant. Interobserver variability was the most important component of total variability (89.3%). A significant rank correlation was found between mean volume and standard deviation ( p < 0.01); the relationship between mean tumor volume and standard deviation can be described using linear regression [standard deviation = 0.28 volume + 0.35 (R = 0.79)]. Conclusion : Total variability in the computed tomography-based measurement of laryngeal tumor volume can be reduced by having the measurement done by a single trained observer.