Assessment of extravascular lung water by quantitative ultrasound and CT in isolated bovine lung

• Bovine lung lobes were studied before and after hypotonic saline instillation.
• Extravascular lung water (EVLW) was assessed by lung ultrasonography (LUS) and CT.
• Quantitative LUS intensity and CT attenuation were weakly correlated.
• LUS intensity correlated with EVLW density more closely than CT attenuation.
• Unlike CT attenuation, LUS intensity was independent of physical density.

Lung ultrasonography (LUS) and computed tomography (CT) were compared for quantitative assessment of extravascular lung water (EVLW) in 10 isolated bovine lung lobes. LUS and CT were obtained at different inflation pressures before and after instillation with known amounts of hypotonic saline. A video-based quantitative LUS analysis was superior to both single-frame quantitative analysis and visual scoring in the assessment of EVLW. Video-based mean LUS intensity was strongly correlated with EVLW density (r2 = 0.87) but weakly correlated with mean CT attenuation (r2 = 0.49) and physical density (r2 = 0.49). Mean CT attenuation was weakly correlated with EVLW density (r2 = 0.62) but strongly correlated with physical density (r2 = 0.99). When the effect of physical density was removed by partial correlation analysis, EVLW density was significantly correlated with video-based LUS intensity (r2 = 0.75) but not mean CT attenuation (r2 = 0.007). In conclusion, these findings suggest that quantitative LUS by video gray-scale analysis can assess EVLW more reliably than LUS visual scoring or quantitative CT.