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 detected at 4.7 T with a good signal‐to‐noise ratio and motion‐suppressed artifacts using a short TE gradient‐echo sequence. Neither cardiac nor respiratory gating were applied, and animals respired freely during data collection. Mean T 2 * relaxation times of parenchyma in the anterior, middle and posterior regions of both lungs ranged between 403 and 657 µs and 397 and 751 µs, 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 regions of both lungs. In the supine position, however, T 2 * values were larger in the posterior and in the anterior portions. For the mouse in both prone 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 concerning asthma models in small rodents. The method was applied to lung inflammation models involving challenge with ovalbumin or lipopolysaccharide. Copyright © 2001 John Wiley & Sons, Ltd. Abbreviations used : ECG electrocardiogram HASTE half‐Fourier single‐shot turbo spin‐echo i.t. intra‐tracheal LPS lipopolysaccharide OA ovalbumin PET positron emission tomography RF radio‐frequency SPECT single‐photon emission computer tomography SW sweep width TE echo time TR repetition time TSE turbo spin‐echo