Temperature monitoring in moving organs during thermal ablation

描述（由申请人提供）：在治疗良性和恶性病变方面，热消融疗法可能比传统手术具有多种优势。与手术相比，热消融可以减少住院时间并显着降低总体治疗成本，并且可能证明对于治疗深部或其他难以到达的肿瘤具有优越性。此外，大多数热消融治疗的微创性质可以减少患者的创伤和疼痛，这在临终姑息治疗中是一个特别有吸引力的优势。热量可以通过激光、射频天线或超声换能器传递，磁共振 (MR) 测温法已用于监测热消融。成像数据必须帮助确认热量是否准确地传递到目标位置，帮助确定目标何时达到致命的热剂量，并确保非目标位置不会被无意损坏。对成像方法的要求尤其具有挑战性，因为在空间、时间和温度维度上同时需要良好的分辨率。虽然 MR 测温技术已成功用于对大脑和子宫等相当容易固定的器官中的病灶进行热消融，但对肝脏等活动性更强的器官进行 MR 监测仍然是一个重大挑战。特别是在聚焦超声消融的情况下，可能没有任何装置或针插入体内，检测和解决运动的任务可能完全落在成像方法上。除了良好的体温测量之外，MR 监测还必须提供足以解析治疗期间自由呼吸患者发生的运动的时间分辨率。拟议的工作旨在开发一种采集、重建和显示包，用于对肝脏等移动器官的热消融进行 MR 监测，能够提供有限的 3D 覆盖，时间分辨率约为 1/2 秒或更好。提出了一种新颖的脉冲序列设计和重建策略，专门针对解决磁共振测温成像中的运动问题。所提出的方法可以提供无失真的 3D 解剖数据，具有良好的信噪比以及用于运动跟踪的灵活对比度，同时还提供准确的温度测量。通过利用所获得的对比度的灵活性，人们可以优先突出显示给定的内部特征，例如血管床，从而提高配准算法检测和跟踪运动的能力。

DESCRIPTION (provided by applicant): Thermal ablation therapy can potentially offer several advantages over traditional surgery in the treatment of both benign and malignant lesions. Compared to surgery, thermal ablation can reduce the length of hospital stays and significantly reduce overall treatment cost, and may prove superior for treating deep-seated or otherwise difficult-to-reach tumors. Furthermore, the minimally-invasive nature of most thermal ablation treatments may reduce trauma and pain for patients, a particularly attractive advantage in the context of end-of-life palliative care. Heat may be delivered with lasers, RF antennas, or ultrasound transducers, and magnetic resonance (MR) thermometry has been used to monitor thermal ablations. The imaging data must help confirm whether heat is being delivered accurately at the targeted location, help determine when a lethal thermal dose has been reached at the target, and make sure that non-targeted locations are not inadvertently damaged. Demands on the imaging method are especially challenging, as good resolution is required along spatial, temporal and temperature dimensions simultaneously. While MR thermometry has been successfully used during thermal ablations of lesions seated in organs that are fairly easily immobilized, such as the brain and uterus, MR monitoring in more mobile organs such as the liver still remains a significant challenge. Especially in the context of focused ultrasound ablation, where there may not be any device or needle inserted into the body, the task of detecting and resolving motion may fall back entirely onto the imaging method. MR monitoring must then provide, in addition to good thermometry measurements, a temporal resolution sufficient to resolve the motion that occurs in free-breathing patients during treatment. The proposed work is aimed at developing an acquisition, reconstruction and display package for the MR monitoring of thermal ablations in mobile organs such as the liver, capable of providing limited 3D coverage with a temporal resolution of about 1/2 second or better. A novel pulse sequence design and reconstruction strategy is proposed, which is specifically targeted toward tackling the motion problem in MR thermometry imaging. The proposed approach can provide distortion-free 3D anatomical data with good signal-to-noise ratio as well as flexible contrast for motion tracking, while also simultaneously providing accurate temperature measurements. By exploiting the flexibility in the obtained contrast, one may preferentially highlight given internal features such as the vascular bed, thus improving the ability of registration algorithms to detect and track motion.