Dynamic imaging of hyperpolarized (3)He distribution in rat lungs using interleaved-spiral scans.

The use of spiral scan techniques is investigated for (3)He lung imaging on small animals. Dynamic series of up to 40 high temporal resolution (3)He ventilation images are obtained using a single bolus of gas. General properties of the spiral technique are discussed and compared to those of standard imaging techniques in relation to the specific case of rare gas imaging. To improve temporal resolution of the image series, the efficiency of a sliding window technique, combining data from two consecutive spiral images, is demonstrated. An example of the typical global (3)He signal variation during the (3)He breathing of the animal is shown. Pixel-by-pixel measurements of the (3)He signal derivative during the gas inspiration are performed. A corresponding lung map of the magnetization per time unit entering the lung during gas inflow is presented.