Chest radiography: estimated lung volume and projected area obscured by the heart, mediastinum, and diaphragm.

PURPOSE: To estimate what fraction of the lung volume and projected lung area are obscured by the heart, mediastinum, and diaphragm on frontal chest radiographs. MATERIALS AND METHODS: Digital images from 25 computed tomographic examinations of the chest (10-mm section thickness and spacing) were analyzed, lung regions were identified in each image section, and simulated frontal radiographs were constructed from the resultant data to estimate the obscured-volume and obscured-area fractions for each patient. Means and standard deviations of the measured lung fractions were computed. RESULTS: On average, 26.4% of the lung volume (standard deviation, 5.1) and 43.0% of the lung area (standard deviation, 6.6) were obscured. CONCLUSION: These substantial lung fractions should be considered in the selection of a screen-film system for chest radiography, because the obscured portion of the lung can be poorly imaged if an inappropriate system is chosen.

Duke Scholars

Author Carl Eric Ravin Radiology, Cardiothoracic Imaging