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

The use of spiral scan techniques is investigated for He-3 lung imaging on small animals. Dynamic series of up to 40 high temporal resolution He-3 ven tilation images are obtained using a single bolus of gas. General propertie s of the spiral technique are discussed and compared to those of standard i maging techniques in relation to the specific case of rare gas imaging. To improve temporal resolution of the image series, the efficiency of a slidin g window technique, combining data from two consecutive spiral images, is d emonstrated. An example of the typical global 3He signal variation during t he He-3 breathing of the animal is shown. Pixel-by-pixel measurements of th e He-3 signal derivative during the gas inspiration are performed. A corres ponding lung map of the magnetization per time unit entering the lung durin g gas inflow is presented. Copyright (C) 2000 John Wiley & Sons, Ltd.