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.