Image interpretation in CT of laryngeal carcinoma: a study on intra- and interobserver reproducibility

The object of our study was to evaluate the intra- and interobserver reproducibility of the interpretation of CT examinations of laryngeal carcinoma. The CT examinations of 100 laryngeal cancers were retrospectively reviewed twice by two independent reviewers. Involvement of different structures was assessed, using a standard scoring form. Statistical analysis was done using the Wilcoxon signed rank test and Cohen's kappa. A borderline significant difference between the observers (p < 0.04) was present. Fair to substantial intraobserver reproducibility (kappa = 0.29–0.86), and fair to substantial interobserver reproducibility (average kappa = 0.26–0.74) were found for most laryngeal structures when a dichotomous categorical scale was used. On the average somewhat lower, but still fair to substantial, intraobserver (kappa = 0.36–0.72), and fair to moderate interobserver (average kappa = 0.29–0.47) reproducibility, were found when a nominal or ordinal categorical scale was used. In conclusion, the interpretation of CT images of laryngeal tumors is reproducible. Received 4 November 1996; Revision received 27 December 1996; Accepted: 2 January 1997