Validation of computed tomography for measuring lung weight.

Area of Science:

• Veterinary Radiology
• Pulmonary Physiology
• Medical Imaging Analysis

Background:

• Lung weight is a key indicator of pulmonary oedema severity and mechanical ventilation response.
• Accurate lung weight measurement is crucial for clinical decision-making in respiratory distress.

Purpose of the Study:

• To assess the accuracy of quantitative computed tomography (CT) for measuring lung weight in pigs.
• To compare in vivo CT measurements with post-exsanguination CT and direct lung weighing.

Main Methods:

• Thorax CT was performed on 36 pigs under varying ventilation conditions to induce or avoid pulmonary oedema.
• Lung weight was measured using a balance post-exsanguination (reference standard).
• Agreement between in vivo CT, post-exsanguination CT, and balance measurements was analyzed using Bland-Altman plots.

Main Results:

• In vivo CT significantly overestimated lung weight (bias -111 g) compared to the balance.
• CT after exsanguination showed good agreement with the balance (bias -9 g), indicating accurate measurement.
• Measurement errors were comparable in pigs with and without pulmonary oedema for both CT methods.

Conclusions:

• In vivo CT overestimates lung weight because it includes pulmonary blood volume.
• CT performed after exsanguination provides accurate and reproducible lung weight measurements.
• Post-exsanguination CT is a reliable method for quantifying lung weight and assessing pulmonary oedema.