title: Accuracy of radiographic lung volume using new equations derived from computed tomography.
abstract: This study compared radiographic measurements of regional lung volume with corresponding physiologic measurements. The database included 48 normal, supine adults who had previously undergone spirometry and helium-dilution lung volume measurements to determine physiologic functional residual capacity (G-FRC) and total lung capacity (G-TLC). Chest x-rays had also been obtained for these subjects at functional residual capacity and total lung capacity. To calculate radiographic lung volumes at functional residual capacity and total lung capacity (R-FRC and R-TLC, respectively), we traced the lung outline from the chest x-ray, and digitized each outline. We then calculated total and regional lung volumes, using equations previously derived from computed tomographic scans. R-FRC and R-TLC were closely correlated (r = 0.973, maximum SEE 6.8%) with G-FRC and G-TLC, whether or not separate equations were used for regions below the diaphragm. Using only maximum anteroposterior diameter reduced the r-value to 0.957 (SEE 9.6%). The accuracy of our method of radiographic measurement of regional lung volume was validated by the concurrence between the physiologic and radiographic measurements.
mesh_terms: D000328:Adult; D003201:Computers; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000502:physiology; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D011859:Radiography; D012115:Residual Volume; D013147:Spirometry; D014109:Total Lung Capacity