Assessing deformable image registration in the lung using hyperpolarized-gas MRI

摘要 放射治疗期间患者解剖特征的位置和方向发生变化，如果不正确 管理，可能导致目标的剂量不足和/或邻近健康组织的剂量过量。 可变形图像配准（Deformable Image Registration，简称形变配准）由于其能够在几何上对齐两幅图像， 在放射治疗中越来越重要，用于管理这些解剖结构变化。测量的准确性直接 影响其临床应用的成功。因此，仔细评估并行计算算法至关重要。 在它们可以被用于告知临床决策之前，它们是必要的。目前的风险评估方法 专注于形态结构，而不是整个变形的生理有效性。最近我们 已经证明了一种新的超极化3 He标记MRI技术，能够直接，在体内， 在区域基础上非侵入性地测量生理肺变形。这种独特的成像技术 对于评估、验证和改进肺部中的呼吸机算法的使用具有很大的希望。我们漫长 长期目标是应用超极化气体标记MRI研究肺生物力学， 完善肺部的放射治疗算法，最终提高肺癌的放射治疗效果。总体目标 本申请的目的是优化超极化3 He标记MRI技术，并确定其用于 评估。目的1是开发和优化基于3D超极化3 He标记的方法学 MRI用于直接测量肺变形。目的二是研制符合生理学要求的数字胸腔模型 基于HP 3 He标记MRI，并证明其用于肺中的放射性评估。成功 这些目标的完成将产生一种基于超极化3 He标记MRI的新方法， 在肺部进行放射治疗评估。它还将产生一些新的磁共振成像技术和一个新的 数字胸部模型系列。测量真实生理肺变形的能力使我们 该技术是一种有前途的工具，用于评估，验证和改进肺部造影算法。本研究 将给研究和临床带来重大变化。在短期内，它可能会给人们带来新的见解， 肺生物力学的复杂性，丰富了我们对肺功能的理解，生成了肺功能的黄金标准数据集， 肺变形，可能有利于研究界，并为临床实施提供指导， DIR.从长远来看，它可能会导致更复杂的放射治疗工具的发展，以改善放射治疗， 肺癌，导致更精确地对肺肿瘤进行放射治疗并减轻辐射- 对周围正常组织造成损伤。

ABSTRACT Changes in the position and orientation of a patient’s anatomical features during radiotherapy, if not properly managed, can lead to underdosage of the target and/or overdosage of neighboring healthy tissues. Deformable image registration (DIR), owing to its ability to geometrically align two images, is becoming increasingly important in radiotherapy for managing these anatomy variations. The accuracy of the DIR directly impacts the success of its clinical applications. Careful assessment of DIR algorithms is therefore a critical necessity before they may be used to inform clinical decision making. Current methods of DIR assessment focus on morphological structures but not on the physiological validity of the entire deformation. Recently, we have demonstrated a novel hyperpolarized 3He tagging MRI technique that is capable of directly, in vivo, and non-invasively measuring physiological lung deformation on a regional basis. This unique imaging technique holds great promise for assessing, validating, and improving the use of DIR algorithms in the lung. Our long term goal is to apply hyperpolarized gas tagging MRI to study lung biomechanics, develop more physiologically sound DIR algorithms for the lungs, and eventually improve radiotherapy of lung cancer. The overall objective of this application is to optimize the hyperpolarized 3He tagging MRI technology and establish its usefulness for DIR assessment. Aim 1 is to develop and optimize a methodology based on 3D hyperpolarized 3He tagging MRI for directly measuring lung deformation. Aim 2 is to develop physiologically sound digital thorax phantoms based on HP 3He tagging MRI and demonstrate their use for DIR assessment in the lung. Successful completion of these aims will yield a novel methodology based on hyperpolarized 3He tagging MRI for DIR assessment in the lung for radiotherapy. It will also yield a number of novel MR imaging techniques and a new series of digital thorax phantoms. The ability to measure true physiological lung deformation makes our technique a promising tool for the assessment, validation, and improvement of lung DIR algorithms. This study will bring important changes to research and the clinic. In the short term, it may lend new insights into the complexities of pulmonary biomechanics, enrich our understanding of DIR, generate gold-standard datasets of lung deformation that may benefit the research community, and provide guidance for clinical implementation of DIR. In the long term, it may lead to development of more sophisticated DIR tools for improving radiotherapy of lung cancer, resulting in more precisely delivered radiation treatment to lung tumors and mitigating radiation- induced injury to surrounding normal tissues.