Visualizing Every Breath You Take
Magnetic resonance images of inhaled 3He gas provide first-ever pictures of complex airflow patterns in mammalian lung
The research is highlighted on the cover of the Journal of Magnetic Resonance (October 2008, see figure). Shown is a common aerodynamic phenomenon known as air streaming. This is depicted as a thin layer of high gas speed (red) that is localized along the outside radius of curvature in the trachea. The cover results also show, for the first time, how airspeed decreases as flowing gas branches along different paths to fill each of the rat’s five lung lobes. This is highlighted by a transition from high gas speed (in red) to slower flow depicted in green and blue. Enlarged View
Results: Airflow patterns in the lung not only determine how well you breathe but also how inhaled materials such as airborne pollutants or aerosolized drugs get distributed inside your body. Researchers from Pacific Northwest National Laboratory and the University of Utah have pioneered a new Magnetic Resonance Imaging method for visualizing inhaled airflow patterns. The method uses hyperpolarized 3He (helium) gas as an inert tracer for visualizing inhaled air speed and direction at each location within the complex, three-dimensional airways of live laboratory rat lungs.
Why it matters: The researchers are currently using 3He MRI for developing and testing computational models of inhaled airflow. These are important not only for predicting where inhaled materials are deposited in the lung, but also for understanding how their fate ultimately affects our health.
Biomedical applications of 3He flow MRI range from improving inhaled drug delivery to monitoring therapeutic response in patients with breathing dissorders like asthma or Chronic Obstructive Pulmonary Disease. The ability to measure alterations in regional lung ventilation also provides a unique opportunity for asssessing the subtle effects of inhaled pollutants, and for improving the assessment of their potential health risks.
What's next: Researchers at PNNL are currently using 3He MRI to develop computer models for describing the breathing lung in health and disease. In one application, this is used to assess the risks associated with common pesticides of interest to the Environmental Protection Agency. They have also begun to use 3He flow MRI to visualize electrochemistry in operating fuel cells as part of ongoing efforts to improve fuel cell operating efficiency and reliability.
Acknowledgments: The research team includes Kevin Minard, Richard Jacob, Daniel Einstein, Andrew Kuprat, Richard Corley and Angie Woodstock, PNNL; and Gernot Laicher and Brian Saam, University of Utah. The work is supported by the National Institutes of Health's National Heart, Lung and Blood Institute, and the research was performed at the Environmental Molecular Sciences Laboratory, a U.S. Department of Energy scientific user facility located at PNNL. This work is advancing science to achieve predictive understanding of multi-cellular biological systems.
Reference: Minard KR, RE Jacob, G Laicher, DR Einstein, AP Kuprat, and RA Corley. 2008. "MR imaging of apparent 3He gas transport in narrow pipes and rodent airways." Journal of Magnetic Resonance 194:182-191.