Rationale and objectives: The authors tested the feasibility of a magnetic resonance (MR) imaging method combining the use of hyperpolarized helium 3 (3He) for ventilation imaging and an arterial spin-tagging sequence for perfusion imaging in six healthy human subjects.
Materials and methods: High-resolution sagittal images depicting 3He distribution were acquired after the subjects' inhalation of 500 mL of laser-hyperpolarized 3He produced by spin-exchange optical pumping. Perfusion MR imaging was performed with a steady-state arterial spin-tagging sequence that enabled the acquisition of three-dimensional images of pulmonary perfusion without the need for subject breath holding.
Results: The 3He ventilation images display, with high signal intensity and detailed anatomic localization, the airspace of the lung parenchyma. The signal intensity on the perfusion images decreased by 23.2% with the use of arterial spin tagging. Ventilation and perfusion were matched, as is expected in healthy subjects.
Conclusion: This method may have important applications in the assessment of lung function, enabling the calculation of regional ventilation-perfusion ratios. It may also aid in the selection of candidates for lung volume-reduction surgery.