Validation of a software designed for computed tomographic (CT) measurement of lung water

Objective:The in-vitro validation of a computed tomographic (CT) software s pecifically designed for quantifying the volume of water contained in the l ung. Design: An in-vitro, ex-vivo study. In 1993, a postmortem left pneumonectom y was performed in a patient who died from acute respiratory distress syndr ome. The lung was fixed, inflated and dried according to a technique propos ed by Markarian and Dailey in 1975 aimed at producing a lung specimen spong y in texture and suitable for radiography. Measurements and results: In 1999, 13 CT scans of this lung specimen were p erformed corresponding to different bronchial instillations of known volume s of water and albumin 4%. The different lung weights resulting from the su ccessive bronchial instillations were calculated using a specially designed software, Lungview, adapted for CT measurements and compared with the actu al lung weight measured by an electronic scale. The increase in lung weight measured by Lungview was closely correlated with the actual increase in lu ng weight resulting from bronchial instillation of water and albumin (y = 0 .99x - 23, r = 1 for water and y = x - 17, r = 1 for albumin 4%) and the pr ecision of the bias was 7 g for water and 3 g for albumin 4%. Conclusions: This study shows that the CT software Lungview accurately meas ured the volume of lung water present within an air-dried exsanguine human lung.