MRI methods for high resolution imaging of the lung

摘要 肺部疾病造成了巨大的经济和社会负担，需要改进诊断工具， 分期，追踪治疗反应。为了评估异质性和局限性的肺部疾病，交叉- 经常进行断层成像，最常见的是使用计算机断层扫描(CT)或放射性示踪剂 (SPECT/PET)。虽然这些技术分别提供结构信息和功能信息，但它们提供了 相当大的辐射剂量，限制了辐射敏感人群和儿科人群的使用。 这项提议旨在通过使磁化来改变目前的肺部成像的临床实践范式 磁共振成像(MRI)是一种有价值的肺部成像手段。核磁共振不会产生电离辐射，因此可以 可用于放射敏感人群的纵向随访或筛查。此外，MRI还提供了多个 基于微结构、通风、灌流、细胞代谢和炎症的参数对比 可以提高对肺部疾病的评估水平。不幸的是，无辐射和多参数的好处 目前临床上不能用于肺部成像，因为肺内信号低，而且对 使用当前的成像方法进行运动。我们小组和其他人最近的发展已经证明 可以对MRI采集范例进行修改，以实现肺部可视化的显著改善 在呼吸机和协作受试者中与CT相媲美，并提供了改善软组织的额外好处 对比度。然而，患者经常患有肺功能不良和/或依从性困难，这 导致复杂、不规则的呼吸和大范围运动，这是目前的MRI技术无法处理的。 我们提出了下一代肺部MRI技术，旨在解决和克服 限制了运动和低肺信号，同时还结合了多种MR软组织对比机制。 这些内容涉及MRI扫描的方方面面，包括患者准备和体验、MRI采集、 以及从数据中重建图像。具体地说，我们开发了一个视听生物反馈系统来 改善患者体验，同时降低复杂运动的可能性，形成多对比 MRI采样策略，最大化嵌入的运动信息，并创建重建 架构，它直接利用MRI数据来估计和校正运动，即使在 复杂的运动。这些方法将有助于确定多种肺部疾病的特征，无论是 儿童和成人人群，包括肺结节、肺栓塞、间质纤维化、囊性 纤维化、慢性阻塞性肺病、哮喘和肺部感染。它们将在儿科领域产生最重大的影响， 在迫切需要限制电离辐射暴露的地方。预计将应用于这一人群， 我们已经包括了对儿科受试者的广泛评估和特定的儿科成像评估 其他原发恶性肿瘤的肺结节。这些结节评估是最常用的 儿科胸部CT在我们的机构，因此是一个实质性的减少剂量的机会。

ABSTRACT There is an enormous economic and social burden of lung disease that demands improved tools to diagnose, stage, and follow treatment response. To assess heterogeneous and localized pulmonary diseases, cross- sectional imaging is often performed, most commonly with computed tomography (CT) or radioactive tracers (SPECT/PET). While these techniques provide structural and functional information, respectively, they deliver considerable radiation dose which limits use in radiosensitive and pediatric populations. This proposal aims to shift the current clinical practice paradigms for pulmonary imaging by making magnetic resonance imaging (MRI) a valuable modality for lung imaging. MRI delivers no ionizing radiation and can thus be used for longitudinal follow-up or screening in radio-sensitive populations. Furthermore, MRI provides multi- parametric contrast based on microstructure, ventilation, perfusion, cellular metabolism, and inflammation that can improve the assessment of lung diseases. Unfortunately, the radiation-free and multi-parametric benefits of MRI are not currently clinically available for lung imaging due to low signal in the lung and sensitivity to motion with current imaging methods. Recent developments by our group and others have demonstrated that the MRI acquisition paradigm can be modified to enable dramatic improvements in the visualization of the lung that rival CT in ventilated and cooperative subjects with the added benefit of providing improved soft tissue contrast. However, patients often suffer from poor lung function and/or have difficulty with compliance, which leads to complex, irregular breathing and bulk motion that cannot be handled by current MRI techniques. We propose a next generation of pulmonary MRI techniques that are designed to address and overcome the limitations of motion and low lung signal while also incorporating multiple MR soft tissue contrast mechanisms. These address all aspects of MRI scanning including patient preparation and experience, the MRI acquisition, and the reconstruction of images from the data. Specifically, we develop an audiovisual biofeedback system to improve the patient experience while also reducing the likelihood for complex motion, develop multi-contrast MRI sampling strategies which maximize embedded motion information, and create a reconstruction architecture which leverages the MRI data directly to estimate and correct for motion even in the case of complex motion. These methods would be beneficial for characterizing numerous diseases of the lung, both in pediatric and adult populations, including pulmonary nodules, pulmonary embolism, interstitial fibrosis, cystic fibrosis, COPD, asthma, and pulmonary infection. They will have the most significant impact in pediatrics, where there is an urgent need to limit ionizing radiation exposure. Anticipating applications to this population, we have included a broad evaluation in pediatric subjects and a specific pediatric imaging evaluation of pulmonary nodules from other primary malignancies. These nodule evaluations are most common use of pediatric chest CT at our institutions, and thus represent a substantial opportunity for dose reduction.