Pulmonary hyperpolarized noble gas MRI: Recent advances and perspectives in clinical application

The invention of hyperpolarized (HP) noble gas MRI using helium-3 (3He) or xenon-129 (129Xe) has provided a new method to evaluate lung function. Using HP 3He or 129Xe for inhalation into the lung air spaces as an MRI contrast agent significantly increases MR signal and makes pulmonary ventilation imaging feasible. This review focuses on important aspects of pulmonary HP noble gas MRI, including the following: (1) functional imaging types, (2) applications for major pulmonary diseases, (3) safety considerations, and (4) future directions. Although it is still challenging to use pulmonary HP noble gas MRI clinically, the technology offers promise for the investigation of the microstructure and function of the lungs.