Gravity-dependent perfusion of the lung demonstrated with the FAIRER arterial spin tagging method

Magnetic resonance imaging of lung perfusion using an arterial spin tagging (AST) sequence called flow sensitive alternating inversion recovery with a n extra RF pulse (FAIRER) was performed in the left and right lateral posit ions in five volunteers. Coronal slices were obtained and the average inten sity of each lung was measured. In both positions, an increase in the inten sity of the dependent lung was found (229% for left lateral, 40% for right lateral). No change was seen along an isogravitational plane. Lung volumes were measured in each position to account for the compression of the lungs by the heart. This effect was found to be symmetric and did not contribute to the perfusion gradient. This demonstrates that AST is sensitive to gravi ty-dependent perfusion gradients in the lung. (C) 2001 Elsevier Science Inc . All rights reserved.