Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Sci Rep. 2019 Feb 20;9(1):2413. doi: 10.1038/s41598-019-38942-8.
While hyperpolarized xenon-129 (HXe) MRI offers a wide array of tools for assessing functional aspects of the lung, existing techniques provide only limited quantitative information about the impact of an observed pathology on overall lung function. By selectively destroying the alveolar HXe gas phase magnetization in a volume of interest and monitoring the subsequent decrease in the signal from xenon dissolved in the blood inside the left ventricle of the heart, it is possible to directly measure the contribution of that saturated lung volume to the gas transport capacity of the entire lung. In mechanically ventilated rabbits, we found that both xenon gas transport and transport efficiency exhibited a gravitation-induced anterior-to-posterior gradient that disappeared or reversed direction, respectively, when the animal was turned from supine to prone position. Further, posterior ventilation defects secondary to acute lung injury could be re-inflated by applying positive end expiratory pressure, although at the expense of decreased gas transport efficiency in the anterior volumes. These findings suggest that our technique might prove highly valuable for evaluating lung transplants and lung resections, and could improve our understanding of optimal mechanical ventilator settings in acute lung injury.
虽然氙-129 （HXe）磁共振成像（MRI）为评估肺部功能方面提供了广泛的工具，但现有的技术仅能提供关于观察到的病理对整体肺部功能影响的有限定量信息。通过选择性地破坏感兴趣容积内的肺泡 HXe 气相磁化，并监测随后从溶解在心脏左心室血液中的氙气信号下降，可直接测量该饱和肺容积对整个肺部气体传输能力的贡献。在机械通气的兔子中，我们发现，当动物从仰卧位转为俯卧位时，氙气的气体传输和传输效率均表现出一种由重力引起的从前到后的梯度，该梯度分别消失或反转。此外，急性肺损伤引起的后部通气缺陷可以通过施加呼气末正压来重新充气，尽管这会导致前部容积的气体传输效率降低。这些发现表明，我们的技术可能对评估肺移植和肺切除术非常有价值，并可能增进我们对急性肺损伤中最佳机械通气设置的理解。
