Magnetic resonance imaging spatial and time study of lung water content in newborn lamb: Methods and preliminary results

To study the lung liquid clearance in vivo at the time of birth, magnetic resonance experiments were conducted on newborn lambs immediately after uterine incision deliverance. Images obtained with a fast spin echo magnetic resonance imaging sequence enable to quantify lung liquid each 5 minutes for 30 minutes, then each 10 minutes for 1.5 hours. After manually determining lung contours, pulmonary volume, pulmonary water, and spatial gradient of pulmonary water were studied. At 2 hours of life, the total pulmonary water content was still high and the liquid clearance was slower in the lower part of the lung. Air inflation increased the size of the distal airways and shifted liquid from the lung lumen towards the pulmonary interstitial tissue. The lung liquid washout was belated, and the passage to the aerial life was performed by progressive liberation of the superior pulmonary spaces, water flowing out by gravity toward the lower spaces.