Waters Barnaby, Owers-Bradley John, Silverman Mike
School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom.
Am J Respir Crit Care Med. 2006 Apr 15;173(8):847-51. doi: 10.1164/rccm.200411-1595OC. Epub 2006 Jan 26.
The apparent diffusion coefficient of hyperpolarized (3)He in the lungs has been shown to correlate directly in animal models with the peripheral airspace size and can detect changes in lung microstructure.
To study in vivo the (3)He apparent diffusion coefficient and to demonstrate its sensitivity to changes in lung morphometry as a result of aging, exposure to cigarette smoke, and lung inflation.
We assessed the variation in the diffusion of hyperpolarized (3)He gas in the lungs by magnetic resonance techniques. Spirometric lung volumes were recorded.
We measured the dependence of (3)He diffusion on age and on reported cigarette smoke exposure in 32 symptom-free adults. We also measured the dependence of the apparent diffusion coefficient on the degree of lung inflation.
In healthy never-smokers, the apparent diffusion coefficient increased with age from 0.115 to 0.155 cm(2) . s(-1) at 20 and 70 yr, respectively, increased linearly with lung inflation and was independent of individual's lung size after correcting for age. For active and passive smokers, the apparent diffusion coefficient increased by up to 40% compared with never-smokers with mean values significantly higher (p=0.016 and p=0.0007, respectively).
Peripheral airspace size increases with age and after exposure to smoke in healthy adults in agreement with previous histologic studies. We have confirmed in vivo that peripheral airspace size is independent of intersubject lung size.
在动物模型中，超极化（3）He在肺中的表观扩散系数已被证明与外周气腔大小直接相关，并且可以检测肺微观结构的变化。
在体内研究（3）He表观扩散系数，并证明其对因衰老、接触香烟烟雾和肺膨胀导致的肺形态测量变化的敏感性。
我们通过磁共振技术评估了超极化（3）He气体在肺中的扩散变化。记录了肺量计测量的肺容积。
我们测量了32名无症状成年人中（3）He扩散对年龄和报告的香烟烟雾暴露的依赖性。我们还测量了表观扩散系数对肺膨胀程度的依赖性。
在健康的从不吸烟者中，表观扩散系数随年龄增长而增加，在20岁和70岁时分别从0.115增加到0.155 cm²·s⁻¹，随肺膨胀呈线性增加，并且在校正年龄后与个体的肺大小无关。对于主动和被动吸烟者，表观扩散系数与从不吸烟者相比增加了高达40%，平均值显著更高（分别为p = 0.016和p = 0.0007）。
与先前的组织学研究一致，健康成年人的外周气腔大小随年龄增长和接触烟雾后增加。我们在体内证实外周气腔大小与个体间肺大小无关。
