A radiographic method for assessing lung area in neonates

The aim of this study was to determine whether computer assisted analysis o f lung area on the chest radiograph reliably predicted lung volume in neona tes. Anteroposterior chest radiographs taken for clinical purposes were sca nned and analysed using a Power Macintosh computer with a Wacom A5 Ultra Pa d and NIH image software. The cardiac, mediastinal and thymic densities and areas of perihilar and lobar consolidation were subtracted from the thorac ic area to give the lung area. This was compared with lung volume, assessed by measurement of functional residual capacity (FRC), within 1 h of the ch est radiograph being performed. 50 infants, median gestational age 30 weeks (range 24-43) were studied. Their median lung area was 11.23 cm(2) (range 0.8-28.53) and lung volume 28 ml (range 3-103). The intraobserver and inter observer coefficients of repeatability of lung area were 1.0 cm(2) and 1.06 cm(2), respectively. Lung area correlated significantly with FRC (r =0.60, p<0.0001). It is concluded that computer assisted analysis of the chest ra diograph lung area is a reliable method of assessing lung volume in neonate s.