Lung Inflation State Dominates Over Intrapulmonary PO2 Regarding T2* of 3He in Human Lungs

Martin H. Deppe¹, Salma Ajraoui¹, Helen Marshall¹, Jim M. Wild¹

This work investigates the influence of O₂ on the T₂^* of hyperpolarized 3He in human lungs. To separate the effect of O₂ from the known lung inflation dependence, T₂^* maps were obtained at expiration and full inspiration, both at baseline breathing air and after 4 min of pure O₂. It is found that the effect of lung inflation dominates over any potential O₂ effect, which is proposed to be due to a combination of motional narrowing and the fact that ³He is distributed over the whole alveolus, while ¹H spins are confined to the interfaces, where susceptibility gradients are strongest.