Dynamic 3HE MRI of the Lungs

描述（由申请人提供）：小气道疾病是发病率和死亡率的重要原因。慢性阻塞性肺疾病（COPD）和哮喘影响着4000万美国人，每年直接医疗支出达230亿美元。如果及早发现，可以通过消除致病因素和实施特定治疗来减缓或停止疾病进展。评估小气道治疗反应的手段是有效应用这些新疗法所必需的，但目前评估肺功能的方法是有限的。临床检查不敏感，通常是非特异性的，并且在全球而不是区域的基础上确定疾病。同样，肺功能测试（pft）只能识别整体缺陷，对小气道疾病不敏感，事实上，75%的气道没有用筛检肺活量测定法进行评估。如果存在，高分辨率CT可以识别区域性解剖性气道改变，但这些改变通常是非特异性的，并不一定反映功能改变的程度。许多气道功能障碍的原因，如哮喘，可能在CT上是不可见的。氦-3磁共振成像（3HeMRI）是最近发展起来的一种观察肺空间和气道的方法。受试者吸入被超极化的He以产生大磁矩，并获得气体的3mr图像。HeMRI对气流减少的区域非常敏感。然而，尽管在吸气和呼气过程中动态获得了He图像，但尚未出现将体积动态成像与气流量化相结合的最佳方法3。该提案的总体目标是开发利用吸入超极化氦的磁共振成像来评估肺功能的多回声方法。具体目标1：确定使用新型移位k- 3空间成像（SKIM）序列进行二维和三维动态平行成像的可行性。假设1.1：未充分采样的脱脂采集与传统的完全采样的自旋翘曲采集具有相同的信噪比，如果不是更高的话。假设1.2：欠采样脱脂序列引入的任何伪影对图像质量的影响可以忽略不计。假设1.3：肺的体积动态功能成像可以通过结合SKIM和平行成像进行。具体目标2：确定使用新的相衬法表征气体流动的可行性。研究将在心流幻影和正常志愿者中进行。假设2.1：所提出的相衬方法可以在编码速度（Venc）为100 cm/s的3He流模研究中绘制气体流速图。假设2.2：该方法可用于绘制正常人气管、主干支气管和左右支气管的气流速度图。本提案的两个目标对于实现我们的最终目标至关重要，即开发一种敏感、可靠的方法来检测病变肺中减少的气体流量。这一提议将代表第一种用于肺血流和功能评估的方法，因此将允许对整个肺功能进行定量评估。小气道疾病是发病率和死亡率的重要原因。如果及早发现，可以通过消除致病因素和实施特定治疗来减缓或停止疾病进展。然而，目前评估肺功能的方法是有限的。我们的建议将代表第一种用于肺血流和功能评估的方法，并将允许对整个肺功能进行定量评估。

DESCRIPTION (provided by applicant): Small airway disease is a significant cause of morbidity and mortality. Chronic obstruction pulmonary disease (COPD) and asthma affect 40 million Americans and cost 23 billion dollars in direct health care expenditure annually. If detected early, disease progression can be slowed or halted by the removal of causative factors, and implementation of specific treatments. Means of assessing therapeutic response of the small airways are necessary to effectively apply these new treatments, but current methods of assessing lung function are limited. Clinical examination is not sensitive, is often non-specific, and identifies disease on a global but not regional basis. Pulmonary function tests (PFTs) similarly only identify global deficiencies and are insensitive to small airway disease, indeed 75% of the airways are not assessed with screening spirometry. High resolution CT can identify regional anatomic airway changes if present, but these are usually non-specific and do not necessarily reflect the degree of functional change. Many causes of airway dysfunction, such as asthma, may be occult to CT. MRI of helium-3 (3HeMRI) is a recently developed method of visualizing lung air spaces and airways. The subject inhales He that has been hyperpolarized to generate a large magnetic moment and an 3 MR image of the gas in acquired. HeMRI is exquisitely sensitive to areas of decreased air flow. However, 3 although He images have been acquired dynamically during inhalation and exhalation, no optimum method 3 has yet emerged for combining volumetric dynamic imaging with airflow quantification. The overarching goal of this proposal is to develop multiecho methods of assessing lung function using magnetic resonance imaging of inhaled hyperpolarized helium, He. SPECIFIC AIM 1: To determine the feasibility of using novel Shifted k- 3 space Imaging (SKIM) sequences for two- and three-dimensional dynamic parallel imaging. Hypothesis 1.1: Undersampled SKIM acquisitions have the same, if not higher, signal-to-noise ratios as conventional fully- sampled spin-warp acquisitions. Hypothesis 1.2: Any artifacts introduced by undersampled SKIM sequences have negligible effects on image quality. Hypothesis 1.3: Volumetric dynamic functional imaging of the lungs can be performed by combining SKIM and parallel imaging. SPECIFIC AIM 2: To determine the feasibility of using a new phase contrast approach for characterizing gas flow. Studies will be performed in flow phantoms and normal volunteers. Hypothesis 2.1: The proposed phase contrast approach can map gas flow velocities in 3He flow phantom studies with an encoding velocity (Venc) of 100 cm/s. Hypothesis 2.2: This approach can be used to map airflow velocities in the trachea, main stem bronchus and right and left bronchi in normal humans. The two aims of this proposal are essential to achieve our ultimate goal of developing a sensitive, reliable method of detecting decreased gas flow in the diseased lung. This proposal would represent the first method developed for flow and functional assessment of the lungs and as such will permit quantitative assessment of the whole lung function. Small airway disease is a significant cause of morbidity and mortality. If detected early, disease progression can be slowed or halted by the removal of causative factors, and implementation of specific treatments. However, current methods of assessing lung function are limited. Our proposal would represent the first method developed for flow and functional assessment of the lungs and will permit quantitative assessment of the whole lung function.