Helium-3 diffusion MR imaging of the human lung over multiple time scales
Helium-3 diffusion MR imaging of the human lung over multiple time scales
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DOI：
10.1016/j.acra.2007.10.009
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发表时间：
2008-06-01
影响因子：
4.8
通讯作者：
Altes, Talissa A.
中科院分区：
文献类型：
--
作者：
Mugler, John P., III;Wang, Chengbo;Altes, Talissa A.
理论基础和目标。超极化He-3气体扩散磁共振成像(MRI)是一种探测肺微结构特征的有力技术。这项技术的一个关键参数是扩散时间，这是允许原子在肺内扩散以测量信号衰减的时间段。讨论了扩散时间与可探索的长度尺度之间的关系，并给出了正在进行的人体肺部扩散时间从毫秒到几秒的具有代表性的初步结果。在1.5T西门子Sonata扫描仪上进行了人肺的He-3扩散磁共振成像。分别使用基于梯度回波和基于刺激回波技术的短扩散时间和中长扩散时间，对两名健康受试者、一名亚临床慢性阻塞性肺疾病患者和一名支气管肺发育不良患者进行了从2毫秒到6.5秒的时间测量。在健康受试者中，随着扩散时间从大约1毫秒增加到1秒，表观扩散系数下降了约10倍，从大约0.2厘米(2)/秒下降到0.02厘米(2)/秒。在有疾病的受试者中的结果表明，在扩散时间大大超过1毫秒时进行测量，可以提高检测肺微结构中某些病理变化的敏感性。通过适当设计的脉冲序列，可以探索超极化~3He在人肺中的扩散，扩散时间的变化超过1000倍。这些测量为探索和表征健康和患病肺的微观结构提供了新的机会。
Rationale and Objectives. Diffusion magnetic resonance imaging (MRI) with hyperpolarized He-3 gas is a powerful technique for probing the characteristics of the lung microstructure. A key parameter for this technique is the diffusion time, which is the period during which the atoms are allowed to diffuse within the lung for measurement of the signal attenuation. The relationship between diffusion time and the length scales that can be explored is discussed, and representative, preliminary results are presented from ongoing studies of the human lung for diffusion times ranging from milliseconds to several seconds.Materials and Methods. He-3 diffusion MRI of the human lung was performed on a 1.5T Siemens Sonata scanner. Using gradient echo-based and stimulated echo-based techniques for short and medium-to-long diffusion times, respectively, measurements were performed for times ranging from 2 milliseconds to 6.5 seconds in two healthy subjects, a subject with subclinical chronic obstructive pulmonary disease and a subject with bronchopulmonary dysplasia.Results. In healthy subjects, the apparent diffusion coefficient decreased by about 10-fold, from approximately 0.2 to 0.02 cm(2)/second, as the diffusion time increased from approximately 1 millisecond to 1 second. Results in subjects with disease suggest that measurements made at diffusion times substantially longer than 1 millisecond may provide improved sensitivity for detecting certain pathologic changes in the lung microstructure.Conclusions. With appropriately designed pulse sequences it is possible to explore the diffusion of hyperpolarized 3He in the human lung over more than a 1,000-fold variation of the diffusion time. Such measurements provide a new opportunity for exploring and characterizing the microstructure of the healthy and diseased lung.