MRI of lung parenchyma in rats and mice using a gradient-echo sequence

Signal of lung parenchymal tissue from the living rat and mouse lung was de tected at 4.7 T with a good signal-to-noise ratio and motion-suppressed art ifacts using a short TE gradient-echo sequence. Neither cardiac nor respira tory gating were applied, and animals respired freely during data collectio n. Mean T-2* relaxation times of parenchyma in the anterior, middle and pos terior regions of both lungs ranged between 403 and 657 mus and 397 and 751 mus, respectively for the rat and mouse. For the rat in the prone position , there was a gradient in T-2* values, from the posterior to the anterior r egions of both lungs. In the supine position, however, T-2* values were lar ger in the posterior and in the anterior portions. For the mouse in both pr one and supine positions, there was a tendential gradient in T-2* from the anterior to the posterior portions. The robustness of the approach renders it well suited for routine applications, e.g. in pharmacological studies co ncerning asthma models in small rodents. The method was applied to lung inf lammation models involving challenge with ovalbumin or lipopolysaccharide. Copyright (C) 2001 John Wiley & Sons, Ltd.