The radial alveolar count method of Emery and Mithal: a reappraisal 1--postnatal lung growth.

The radial alveolar count method of Emery and Mithal has been re-evaluated on 76 normal postnatal lungs. Results of reproducibility assessments suggest that each observer should establish normal control values when beginning with the method, and should subsequently use control cases to maintain strict reproducibility. The use of 10 fields per case was found to be inadequate to obtain satisfactory reproducibility, even for a single observer. Prior inflation of the lungs significantly increased the radial counts, and this factor may help to explain the large discrepancy between the results of this study and that of Emery and Mithal. The radial counts correlated well with the chronological age of the child (r = +0.76; p less than 0.001). Alveolarization of the acinus occurs primarily between birth and 2 years; significant but slower growth is seen up to 8 years, after which the results plateau, suggesting that alveolarization is complete. The radial count method appears to provide a relatively simple and reasonably satisfactory assessment of alveolar development, as originally proposed by Emery and Mithal.