Emir Osmanagic1, Alexander L. Sukstanskii2,
Mark S. Conradi3, James D. Quirk2, Dmitriy A.
Yablonskiy2
1Electrical and Systems Engineering,
Washington University, St. Louis, Misssouri, United States; 2Radiology,
Washington University, St. Louis, Misssouri, United States; 3Physics,
Washington University, St. Louis, MO, United States
Diffusion-attenuated
MR signal of 3He gas in lungs demonstrate non-mono-exponential dependence on
b-value. It was previously suggested that such behavior is a result of
microscopically anisotropic but macroscopically isotropic nature of lung
microstructure: diffusion in each airway is anisotropic, while distribution
of airway axes directions is isotropic. Hypothetically such
non-mono-exponential dependence would also be present in a system of multiple
spherical compartments (mimicking alveoli) with a variety of sizes. Herein,
we used experiments with three consecutive bipolar gradient pulses with
orthogonal and parallel gradient orientations to discriminate between such
two systems. Our result confirmed microscopically anisotropic hypothesis.