INTEROBSERVER VARIABILITY IN CT AND MR STAGING OF LUNG-CANCER

Objective: Our goal was to assess the interobserver variability in sta ging non-small cell lung cancer using CT and MRI. Materials and Method s: As part of the Radiologic Diagnostic Oncology Group (RDOG) study of lung cancer staging, the CT and MR examinations of 40 patients suspec ted of having non-small cell bronchogenic carcinoma were blindly inter preted by four expert observers. The primary tumor and lymph node stag es in the 40 study subjects were similar to the final proportions repo rted in the RDOG study. Assessed abnormalities included the presence o f a lung nodule, chest wall invasion, mediastinal invasion, bronchial involvement, lymph node metastasis in specific node stations, and T an d N classifications. Percent agreement and kappa-values were calculate d for each of these determinations. Results: Depending on the finding assessed and the method of analysis, average agreement rates ranged fr om 58 to 90% for CT and from 61 to 96% for MRI. Average kappa-values w ere largely between 0.40 and 0.60 when dichotomous analysis was used; weighted kappa-values were similar. With a single exception, no signif icant differences were found for kappa-values calculated for CT and MR I. Conclusion: Although interobserver agreement rates are good for det ermining T and N classification in patients with lung cancer, variabil ity in image interpretation is frequent, even among experienced observ ers.