Usefulness of concurrent reading using thin-section and thick-section CT images in subcentimetre solitary pulmonary nodules

Abstract

Aim: To evaluate the differences in the characterization and recommendation for follow-up of subcentimetre solitary pulmonary nodules (SSPNs) between 5 and 1 mm section CT, and to compare the assessments generated by four radiologists. Materials and methods: Five hundred and twenty-nine patients who had SSPNs on chest CT reconstructed using both 5 and 1 mm sections were enrolled. Two image subsets of 5 and 1 mm CT images of each nodule were interpreted independently by four radiologists. Nodule size, consistency (solid, partly solid, non-solid), the presence of calcification, and recommendations for follow-up were evaluated. If a non-calcified solid nodule was confirmed using CT, recommendation for follow-up was based on Fleischner Society guidelines. Data assessed by each radiologist were compared, and interobserver agreements were determined using the intraclass correlation coefficients and kappa value. Results: Using 1 mm CT images, the nodule sizes were significantly larger than on 5 mm CT images (paired t-test, p < 0.01). The presence of calcification and nodule consistency were significantly different between 5 and 1 mm CT images (McNemar test for the presence of calcification, p < 0.01; Wilcoxon signed test for nodule consistency, p < 0.01). On 1 mm CT images there was significantly higher agreement regarding nodule consistency than on 5 mm CT (kappa = 0.78 and 0.67, respectively). Conclusions: Concurrent use of thin-section and thick-section CT can provide more accurate nodule assessment and higher interobserver agreement in SSPN. © 2008 The Royal College of Radiologists.