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To validate a fast gradient echo sequence for rapid (9 s) quantitative imaging of lung water.

Eleven excised pig lungs were imaged with a fast GRE sequence in triplicate, in the sagittal plane at 2 levels of inflation pressure (5 and 15 cm H₂O), an intervention that alters T₂*, but not total lung water. Images were acquired alternating between two closely‐spaced echoes and data were fit (voxel‐by‐voxel) to a single exponential to determine T₂* and water content, and compared with gravimetric measurements of total water.

T₂* averaged 1.08 ± 0.02 ms at 5 cm H₂O and 1.02 ± 0.02 ms at 15 cm H₂O (P < 0.05). The measure was reliable (R² = 0.99), with an average mean error of 1.8%. There was a significant linear relationship between the two measures of water content: The regression equations for the relationship were y = 0.92x + 19 (R² = 0.94), and y = 1.04x + 4 (R² = 0 …