Quantitative evaluation of neonatal lung expansion with automated image analysis

Lung sections from artificially ventilated premature newborn rabbits, some treated with natural surfactant, were examined microscopically with an IBAS image analyzer connected to a television camera. The "stereological profile" of the alveoli was determined by automatical evaluation of the following parameters: volume density (VV), and its coefficient of variation (CV(VV), surface density (SV), average mean integral surface curvature (K), and a "shape factor" (SF) measuring the "circularity" of sectioned alveoli. Data from image analysis were closely correlated to those obtained with conventional morphometrical techniques (e.g., r = 0.92 for VV). Alveolar expansion was significantly improved after treatment with surfactant, especially in animals ventilated with prolonged inspiration phase. We suggest that image analysis is a useful method for evaluating alveolar expansion patterns in the neonatal lung.