MEASUREMENT OF LUNG EXPANSION WITH COMPUTED-TOMOGRAPHY AND COMPARISONWITH QUANTITATIVE HISTOLOGY

The total and regional lung volumes were estimated from computed tomog raphy (CT), and the pleural pressure gradient was determined by using the milliliters of gas per gram of tissue estimated from the X-ray att enuation values and the pressure-volume curve of the lung. The data sh ow that CT accurately estimated the volume of the resected lobe but ov erestimated its weight by 24 +/- 19%. The volume of gas per gram of ti ssue was less in the gravity-dependent regions due to a pleural pressu re gradient of 0.24 +/- 0.08 cmH(2)O/cm of descent in the thorax. The proportion of tissue to air obtained with CT was similar to that obtai ned by quantitative histology. We conclude that the CT scan can be use d to estimate total and regional lung volumes and that measurements of the proportions of tissue and air within the thorax by CT can be used in conjunction with quantitative histology to evaluate lung structure .