Traditional Posters: Body Imaging

Matthew S. Fox^1,2, Alexei Ouriadov¹, William Dominguez-Viqueira^1,3, Marcus Couch^1,2, Giles E. Santyr<sup>1,3

1</sup>Imaging, Robarts Research Institute, London, Ontario, Canada; ²Physics and Astronomy Dept, University of Western Ontario, London, Ontario, Canada; ³Medical Biophysics, University of Western Ontario, London, Ontario, Canada

Hyperpolarized ¹²⁹Xe is a novel gaseous contrast agent which also dissolves in the lung parenchyma and blood compartments, offering an interesting palette of potential biomarkers of pulmonary disease. ¹²⁹Xe signals from the dissolved compartments have different chemical shifts and can be selectively saturated and allowed to recovery as a function of delay time as in the chemically selective saturation recovery (CSSR) technique. We collected CSSR data and 3D volumes from rat lungs in-vivo and explore both the Butler and Mansson model for estimations of surface to volume ratio, diffusing capacity and tissue transit time.

2548. Anisotropic Nature of 3He Gas Diffusion in Mice Lungs

Emir Osmanagic¹, Alexander L. Sukstanskii², Mark S. Conradi³, James D. Quirk², Dmitriy A. Yablonskiy<sup>2

1</sup>Electrical 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.

2549. Quantitative Assessment of Lung Microstructure in Healthy Mice Using Lung Morphometry with Hyperpolarized 3He Diffusion MRI

Emir Osmanagic^1,2, Alexander L. Sukstanskii³, James D. Quirk³, Jason C. Woods^3,4, Mark S. Conradi⁴, Dmitriy A. Yablonskiy<sup>3,5

1</sup>Electrical and Systems Engineering, Washington University, St. Louis, Misssouri, United States; ²Radiology, Washington University, St. Louis, MO, United States; ³Radiology, Washington University, St. Louis, Misssouri, United States; ⁴Physics, Washington University, St. Louis, MO, United States; ⁵Physics, Washington University, St. Louis, Misssouri, United States

Lung morphometry technique with hyperpolarized 3He allows quantification of lung geometrical parameters such as mean chord length Lm, surface-to-volume ratio S/V and density of alveoli. It was demonstrated that in humans, it provides results similar to direct morphological measurements. Two important modifications, however, are required to adopt this technique for studying lung microstructure in small animals – reduction in diffusion time and modification of theoretical relationship between diffusion MR signal and lung microstructural parameters. Herein we provided such modifications and demonstrated that measurements obtained with lung morphometry with hyperpolarized 3He MRI in mice are in agreement with literature data.

2550. The Effect of Locally Administered Glucocorticoid Budesonide on Ovalbumin Exposed Rats Assessed by HP ³He MRI