To implement and evaluate a noninvasive magnetic resonance method of pulmonary perfusion imaging in healthy volunteers. A respiratory-triggered. three-dimensional gradient-echo pulse sequence is used with an extremely short echo-time (TE) to allow observation of the lung parenchyma without the need for breatholding. Continuous magnetic labeling of the pulmonary blood flow is effected by flow-induced adiabatic fast passage inversion. Estimated correction for off-resonance effects due to the labeling pulse is performed. Images acquired under conditions of arterial spin labeling are subtracted from control images to yield a three-dimensional image of the signal change induced by arterial labeling. Data are acquired before and after exercise in a subset of subjects. Uniform signal intensity changes are observed to the level of the parietal pleura in all subjects. This method provides high-resolution three-dimensional images which reflect regional pulmonary blood flow and volume without the need for breatholding. We anticipate that it will be useful in the evaluation of patients with pulmonary disease, especially in the diagnosis of pulmonary thromboembolic disease.
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