Background and Purpose
Improvement of the resolution with rapid scanning in multidetector-row computed tomography (MDCT) increases accuracy to demonstrate the relationship of pulmonary artery and lung lesion, even in the peripheral lung. The aim of this study is to evaluate the ability of the relationship between pulmonary artery and lung lesion to distinguish benign lung lesion from malignancy and the degree of pulmonary arterial encasement in predicting malignancy is evaluated with receiver operating characteristic (ROC) curve.
Materials and Methods
A total of 100 lung nodules/masses of 16-slice MDCT data were included in this study. Dynamic CT images of 77 bronchogenic carcinomas and 23 benign lung lesions were independently assessed by 2 observers who were unaware of the final diagnosis of each lesion. They recorded the relationships of the lung lesion and adjacent pulmonary artery as encasement, displacement, penetration, in the margin and disconnection. Correlation of the relationships with the pathologic findings was also performed. Fisher’s exact test and odds ratio (OR) with its 95% confidence interval (CI) were used to analyze the relationship of pulmonary artery to lesion with the possibility of malignancy. The degree of pulmonary arterial encasement in the benign lesion and malignancy was evaluated by Wilcoxon rank sum test. The agreement between 2 observers was evaluated by kappa (κ) statistics. In addition, the sensitivity and specificity profiles of the degree of encasement in diagnosis of malignancy were determined by plotting an empirical ROC curve.
Results
The relationship between pulmonary arteries and lung lesions had a statistically significant difference in benign from malignancy (p<0.001). [When using penetration as baseline; the OR for encasement was 18.1, (95% CI: 4.6-71.7, p< 0.001); the OR for displacement was 33.7, (95% CI: 5.3-213.7, p = 0.0002)]. Inter-observers’ agreement was very good (κ = 0.819; 95% CI: 0.718-0.919). The average degree of pulmonary arterial encasement in benign lesion and malignancy were 52.1 % ± 27.3 % and 71.8% ± 18.8%, respectively (p = 0.011). The ROC curve showed that the degree of pulmonary arterial encasement has a moderate discriminating ability in diagnosing lung carcinoma, and the area under the curve was 0.738. The best cut-off value was 44.4%. All lesions with pulmonary arterial encasement had microscopic vascular invasion while lesions with pulmonary arterial penetration did not have vascular invasion.
Conclusions
The relationship of pulmonary artery to the lung lesion and degree of pulmonary arterial encasement could be used in differentiating benignancy from malignancy not only for central lung lesions but also peripheral lung lesions and this would decrease biopsy rate. Furthermore, pulmonary arterial encasement implies microscopic vascular invasion which is related to a poor prognosis.
