Dynamic spiral MRI of pulmonary gas flow using hyperpolarized He-3: Preliminary studies in healthy and diseased lungs

An optimized Interleaved-spiral pulse sequence, providing high spatial and temporal resolution, was developed for dynamic imaging of pulmonary ventila tion with hyperpolarized He-3, and tested in healthy volunteers and patient s with lung disease. Off-resonance artifacts were minimized by using a shor t data-sampling period per Interleaf, and gradient-fidelity errors were com pensated for by using measured k-space trajectories for image reconstructio n. A nonsequential acquisition order was implemented to improve image quali ty during periods of rapid signal change, such as early inspiration. Using a sliding-window reconstruction, cine-movies with a frame rate of 100 image s per second were generated. Dynamic images demonstrating minimal susceptib ility- and motion-induced artifacts were obtained In sagittal, coronal, and axial orientations. The pulse sequence had the flexibility to image multip le slices almost simultaneously. Our initial experience in healthy voluntee rs and subjects with lung pathology demonstrated the potential of this new tool for capturing the features of lung gas-flow dynamics. (C) 2001 Wiley-L iss, Inc.