Objective: Expiratory films are regarded as being superior to inspiratory films for pneumothorax detection, yet this has not been proved. In the current study, we compared inspiratory versus expiratory chest radiographs for pneumothorax detection.
Materials and methods: Eighty-five paired inspiratory and expiratory radiographs with pneumothoraces and 93 pairs without pneumothoraces were randomly arranged and reviewed independently by three radiologists. A score of 1-5 was assigned for each hemithorax (5 = definite pneumothorax, 1 = definitely no pneumothorax). Results were compared for inspiration and expiration using receiver operating characteristic (ROC) analysis.
Results: The average area under the ROC curves for all readers was .973 for inspiration and .972 for expiration (nonsignificant). McNemar's test and an alpha level of .05 also yielded no significant difference in sensitivity and specificity. Four of the 85 cases were scored as definite pneumothorax on inspiration and as definitely not on expiration by all readers, and three of the 85 cases were scored as definite pneumothorax on expiration and as definitely not on inspiration.
Conclusion: Inspiratory and expiratory upright films are equally sensitive for pneumothorax detection. Given the limitations of expiratory films, inspiratory films are recommended as the initial examination of choice for pneumothorax detection.