Three Dimensional Volumetric Analysis Of Pulmonary Nodules On Chest CT:Cancer Risk Assessment

ObjectiveThe management of pulmonary nodules relies largely on cancer risk assessment, in which the only widely accepted criterion is diameter. The development of volumetric computed tomography(CT) and three-dimensional(3D) software enhances the clarity in displaying the nodules’ characteristics. The object of this study is to the values of the nodules’ volume and 3D morphological characteristics(edge, shape, and location) in cancer risk assessment. MethodsThe CT data of 200 solid pulmonary nodules and 33 non-solid pulmonary nodules were retrospectively evaluated using 3D volumetric software. All nodules were less than 3 cm in diameter. Malignant nodules were confirmed by pathology or histology, benign solid nodules were confirmed by pathology or no change during two-years follow-up( Less than 25% of volume change), Non-solid nodules follow-up two-years of no change was defined as indeterminateness. Logistic regression analysis was performed to calculate the odds ratios(ORs) of 3D margin(smooth, lobulated, speculated/irregular), shape(spherical, non-spherical), location(Purely intraparenchymal, Juxtavascular, Pleural-attached) and nodules volume on cancer risk assessment for total nodules, sub-centimeter nodules and non-solid nodules respectively. The receiver operating characteristic curve(ROC curve) was used to determine the optimal threshold for solid pulmonary nodule volume. ResultsOf 200 solid nodules(benign112, malignant 78) and 33 non-solid nodules(unknown 11, malignant 22) were retrospectively enrolled. The logistic regression analysis showed the volume(OR=3.3; p<0.001) and 3D margin(lobuated, spiculated/irregular margin, OR=13.4, 9.8; both p=0.001) were independent predictive factors of malignancy, while the location and 3D shape had no predictive value(p>0.05) for total. ROC analysis showed the optimal threshold for malignancy is 666 mm3. For sub-centimeter nodules, the 3D margin was the only valuable predictive factor of malignancy(OR=60.5, 75.0; p=0.003, 0.007). As the non-solid nodules were concerned, Fisher’s exact test analysis determined that the density(p=0.03), edge shape(p=0.07), diameter(p=0.002) and the volume(p=0.01) had statistically significant effect on the differential diagnosis, whereas, the position(p=0.70) and the three-dimensional shape(p=0.38) had no statistically significant(p> 0.05). The logistic regression analysis showed that the volume(OR=3.7; p<0.05) was the only independent predictive factors of malignancy, whereas the density and edge shape exhibited no significant predictive value(p>0.05). Conclusion1. The volume and 3D margin are valuable to assess the cancer risk of pulmonary nodules, volume larger than 666 mm3 can be determined as high-risk nodules.2. For sub-centimeter nodules, lobulated, spiculated or irregular margin have a high probability to be malignant.3. For non-solid nodules, the volume was the only valuable characteristics in assessing the malignant risk, the density and edge shape had no statistically significant.