Alternative Agreement Approaches in Testing the Agreement of Three-dimensional Computerized Tomography Measurements of Styloid Processes by Two Observers at Two Different Times*

Aim: This study aimed to evaluate the intraobserver and interobserver agreement of styloid process (SP) measurements on three-dimensional (3D) computerized tomography (CT) images between two experienced radiologists by using the concordance correlation coefficient (CCC) and coefficient of individual agreement (CIA) agreement statistical methods. Materials and Methods: Contrast-enhanced carotid CT angiography images of 68 patients, performed between June 2015 and December 2015, were evaluated retrospectively. The length between the attachment point of the SP to the temporal bone and the distal end was measured on 3D CT images performed with a 64-slice CT scanner. Both the agreements between the two radiologists and the replicated measurements of each radiologist were calculated with the help of CIA and CCC agreement indexes. Results: When CIA was used for agreement statistics, the two radiologists disagreed in the right and left measurements of the individual. When the CCC agreement statistic was used, there was a perfect agreement between the measurements of the two radiologists. Discussion and Conclusion: The variance values of between-subject and within-subject should be taken into consideration for each observer in cases of two replicated measurements. If these values show very large differences from each other, CCCtotal values may have been calculated larger than the real value. However, the CIA statistics value is more stable and when such a case is encountered, researchers are advised that between-subject and within-subject variances should be calculated due to the differences between the two replicated measurements of each observer. Therefore, the 2 2 W B rate should absolutely be taken into consideratio