Receiver operating characteristic (ROC) curve for HRCT variables.

<p>The area under ROC curve (AUC) for lesion diameter was 0.760 (A), the AUC for mean HRCT attenuation 0.793 (B), and the AUC for lesion volume 0.898 (C). The optimal cut-off value used for lesion diameter, mean HRCT attenuation and volume to differentiate pre-invasive lesions from MIA was 8.18 mm (sensitivity, 75.0%; specificity, 71.8%; PPV, 44.8%; and NPV, 52.7%), -602 HU (sensitivity, 71.4%; specificity, 76.9%; PPV, 49.1%; and NPV, 50.6%), and 0.33 cm3 (sensitivity, 78.6%; specificity, 87.2%; PPV, 51.9%; and NPV, 48.8%), separately.