Effect of lung inflation on arterial spin labeling signal in MR perfusion imaging of human lung

The effect of lung inflation on arterial spin-labeling signal in lung perfu sion is Investigated. Arterial spin-labeling schemes, called alternation of selective inversion pulse (ASI) and its hybrid (HASI), which uses blood wa ter as an endogenous, freely diffusible tracer, were applied to magnetic re sonance (MR) perfusion imaging of the lung. Perfusion-weighted images of th e lung from nine healthy volunteers were obtained at different time delays. There was a significant signal difference in ASI images acquired at differ ent respiratory phases. Greater signal enhancement has been observed when t he volunteers performed breath holding on end expiration than on end inspir ation. This is in agreement with the normal physiologic effect of lung infl ation on the pressure-flow relationship of pulmonary vasculature. ASI and H ASI perfusion-weighted images show similar lung features and Image quality. Preliminary results from pulmonary embolism patients indicate that arteria l spin labeling is sensitive for the detection of areas of perfusion defici t. J. Magn. Reson. Imaging 2001;13:954-959. (C) 2001 Wiley-Liss, Inc.