Table 2.
Linear regression analysis
| Model | Dependent variable | Independent variables | Coeffecient [CI] | p value |
|---|---|---|---|---|
| a | HU | IC | 23.36 [19.64, 26.49] | < 0.0001 |
| Primary lung cancer | 9.85 [5.4, 13.85] | < 0.0001 | ||
| Pulmonary metastasis | Reference | |||
| b | HU | Zeff | 39.9 [34.12, 44.72] | < 0.0001 |
| Primary lung cancer | 8.43 [3.63, 12.62] | 0.0003 | ||
| Pulmonary metastasis | Reference | |||
| c | Zeff | IC | 0.50 [0.46, 0.55] | < 0.0001 |
| Primary lung cancer | 0.02 [− 0.04, 0.07] | 0.59 | ||
| Pulmonary metastasis | Reference |
CI indicates bootstrapped 95% confidence interval (2000 replicates). IC, iodine concentration on dual-energy computed tomography; HU, conventional computed tomography attenuation values in Hounsfield units; Zeff, effective atomic number. Italics indicate significant p values (< 0.05). Note that two-way interaction terms for all three models were not significant in preliminary analyses