The importance of risk models for management of pulmonary nodules

Pulmonary nodules are a frequent finding in computed tomography (CT) investigations. Further diagnostic work-up of detected nodules mainly depends on the so-called pre-test probability, i.e. the probability that the nodule is malignant or benign. The pre-test probability can be calculated by combining all relevant information, such as the age and the sex of the patient, the smoking history, and history of previous malignancies, as well as the size and CT morphology of the nodule. If additional investigations are performed to further investigate the nodules, all results must be interpreted taking into account the pre-test probability and the test performance of the investigation in order to estimate the post-test probability. In cases with a low pre-test probability, a negative result from an exact test can exclude malignancies but a positive test cannot prove malignancy in such a setting. In cases with a high pre-test probability, a positive test result can be considered as proof of malignancy but a negative test result does not exclude malignancy.