Can lung weight be measured by computed tomography?

Introduction Computed Tomography (CT) may be a non-invasive tool for measuring lung weight (a surrogate of edema) in vivo [1]. Aim To compare lung weight measured with the balance with lung weight measured with CT scan. Methods Thirteen sedated and mechanically ventilated piglets (21 ± 3 Kg) underwent lung CT at the end of different experimental protocols and were then sacrificed. Lungs were excised and weighed on a balance. Pre-mortem CT scans were manually delineated and processed with a dedicated software (quantitative analysis). Lung weights measured with the balance (reference) were compared with those obtained with CT. Results Lung weight measured with the balance was 407 ± 236 g and lung weight obtained by quantitative analysis of CT scan was 509 ± 232 g (P < 0,001; paired t-test). Comparison between the two methods is reported in Figure. Figure. Bland & Altman plot. X axis: mean of the results obtained with the two methods. Y axis: difference between the two results (lung weight measured with the balance acted as reference method). Conclusions On average, CT overestimated lung weight (as measured with the balance) by 100 g. Since CT scan was taken before autopsy (and exsanguination) this discrepancy is likely explained by greater (and heavier) pulmonary blood content.[1] Gattinoni L., Cressoni M., Intensive Care Med, 2010; 36:1803-1804