RESUMO
Anatomists and radiologists use the Zaidi-Dayal and Richards-Jabbour scales to study the shape of the foramen magnum. Our aim is to measure the interrater and intrarater agreement and reliability of ratings made using the two scales. We invited 16 radiology residents to attend two sessions, four weeks apart. During each session, we asked the residents to classify the shape of the foramen magnum in 35 images using both scales. We used Fleiss' κ to measure interrater reliability and Cohen's κ to measure intrarater reliability. The interrater reliability of ratings made using the Zaidi-Dayal scale was 0.34 (0.26-0.46) for session one and 0.30 (0.24-0.39) for session two, and the intrarater reliability was 0.39 (0.34-0.44). The interrater reliability of ratings made using the Richards-Jabbour scale was 0.14 (0.10-0.19) for session one and 0.12 (0.09-0.17) for session two, and the intrarater reliability was 0.11 (0.07-0.15). In conclusion, the interrater and intrarater agreement and reliability of ratings made using the Zaidi-Dayal and Richards-Jabbour scales are inadequate. We recommend an objective method by Zdilla et al. to researchers interested in studying the shape of the foramen magnum.