Isabel Dregely1, Iulian C. Ruset2,
Jeff Ketel2, Steve Ketel2, Jaime F. Mata3,
Talissa A. Altes3, G. Wilson Miller3, John P. Mugler
III3, F. W. Hersman1,2, Kai Ruppert3
1Physics, University of New Hampshire,
Durham, NH, United States; 2Xemed LLC, Durham, NH, United States; 3Radiology,
University of Virginia, Charlottesville, VA, United States
We
investigated the response of rabbit lungs to different lung ventilation
volumes using 3D multiple-exchange time xenon polarization transfer contrast
(MXTC) MRI. From the subsequently fitted exchange time constant of the xenon
exchange between alveolar air spaces and the surrounding septal walls, the
tissue thickness can be calculated. The long exchange time limit allows calculation
of the tissue-to-alveolar volume ratio. We observed increased
tissue-to-alveolar volume ratio in posterior partitions and decreased septal
wall thickness in anterior partitions at low lung volumes. At high
ventilation volumes these differences disappear.