Using MRI to measure aerosol deposition.

This article provides a concise review of the use of magnetic resonance imaging (MRI) for measurement of regional aerosol deposition in the lungs. Basic aspects of MRI and its use in lung imaging and measurement of regional ventilation are introduced. Imaging of hydrogen protons (water) and inhaled hyperpolarized gases as the MRI source signals are discussed. The addition of contrast agents to aerosol particles in order to allow measurement of regional aerosol deposition is considered. Existing in vitro human and in vivo animal model measurements of regional aerosol deposition in the respiratory tract demonstrate the capability of MRI in this regard. However, as a tool for human deposition studies, current approaches require contrast agent doses that are too high to be considered competitive with traditional radionuclide aerosol deposition measurement methods. Thus, future use of MRI in human studies of regional aerosol deposition is predicated on improvement over present approaches.