Observer Variability and the Performance between Faculties and Residents: US Criteria for Benign and Malignant Thyroid Nodules

Objective: To evaluate the interobserver variability and performance in the interpretation of ultrasonographic (US) findings of thyroid nodules. Materials and Methods: 72 malignant nodules and 61 benign nodules were enrolled as part of this study. Five faculty radiologists and four residents independently performed a retrospective analysis of the US images. The observers received one training session after the first interpretation and then performed a secondary interpretation. Agreement was analyzed by Cohen's kappa statistic. Degree of performance was analyzed using receiver operating characteristic (ROC) curves. Results: Agreement between the faculties was fair-to-good for all criteria; however, between residents, agreement was poor-to-fair. The area under the ROC curves was 0.72, 0.62, and 0.60 for the faculties, senior residents, and junior residents, respectively. There was a significant difference in performance between the faculties and the residents (p < 0.05). There was a significant increase in the agreement for some criteria in the faculties and the senior residents after the training session, but no significant increase in the junior residents. Conclusion: Independent reporting of thyroid US performed by residents is undesirable. A continuous and specialized resident training is essential to enhance the degree of agreement and performance.