Aerosols and gaseous contrast agents for magnetic resonance imaging of the lung.

Magnetic resonance imaging of lungs and the investigation of pulmonary pathologies with this technique are limited by low proton spin density, degraded magnetic homogeneity and motion. Inhaled contrast agents (gases or aerosols) can improve the diagnostic value of MRI for lung. Paramagnetic contrast agents such as gadolinium chelates aerosol or dioxygen gas increase the relaxivity of proton in lung parenchyma and can be used to assess the ventilated fraction of the bronchoalveolar space. Similarly, inhalation of non proton-MRI nuclei such as perfluorinated gas or hyperpolarized gases ((3)He or (129)Xe) can provide functional ventilation image. In this review paper, the principles, the practical implementation, the limitations and possible safety issues of these different techniques are summarized. The main pre-clinical and clinical applications of these approaches based on oral contrast agents are reviewed and illustrated with cutting-edge lung MRI studies.
((c) 2008 John Wiley & Sons, Ltd.)