MR tagging of human lungs using hyperpolarized 3 He gas

Purpose To evaluate the use of spin‐tagging in conjunction with hyperpolarized gas imaging for monitoring lung ventilation and gas diffusion. Methods and Materials Images were taken at 0.15 T using single shot RARE, with hyperpolarized 3 He gas prepared by the metastability exchange technique. Sinusoidal modulation of the longitudinal magnetization (tag) was produced by two 90‐degree rf pulses separated by a gradient pulse. The diffusion of 3 He gas in the lungs was measured by monitoring the decay of the tags. This study was conducted on a 25‐year‐old, male, healthy volunteer. Results Clear tags in hyperpolarized 3 He gas both in vivo and in vitro were generated. The relative movement of the lung compared to a static, partial breath‐hold was measured following inspiration or expiration. The diffusion coefficient of 3 He in the lungs was found to be 0.02 ± 0.005 cm 2 seconds ‐1 . Conclusion The spin‐tagging of hyperpolarized 3 He in the lungs is possible, and allows regional lung movements to be measured following inspiration and expiration. It also allows quantification of the diffusion of the 3 He gas. J. Magn. Reson. Imaging 2003;17:142–146. © 2002 Wiley‐Liss, Inc.