Temperature monitoring in moving organs during thermal ablation

描述（由申请人提供）：与传统手术相比，热消融治疗在治疗良性和恶性病变方面可能具有几项优势。与手术相比，热消融可以缩短住院时间并显著降低总体治疗成本，并且可以证明对于治疗深部或难以到达的肿瘤具有上级优势。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，这在临终姑息治疗的背景下是一个特别有吸引力的优势。可以用激光器、RF天线或超声换能器递送热量，并且磁共振（MR）测温法已经用于监测热消融。成像数据必须有助于确认热量是否准确地输送到目标位置，帮助确定何时达到致命的热剂量，并确保非目标位置不会受到意外损坏。对成像方法的要求尤其具有挑战性，因为同时需要沿着空间、时间和温度维度的良好分辨率。虽然MR温度测量已成功地用于位于相当容易固定的器官（例如大脑和子宫）中的病变的热消融期间，但在更移动的器官（例如肝脏）中的MR监测仍然是一个重大挑战。特别是在聚焦超声消融的背景下，其中可能没有任何设备或针插入体内，检测和解析运动的任务可能完全回到成像方法上。除了良好的温度测量外，MR监测还必须提供足以解决治疗期间自由呼吸患者中发生的运动的时间分辨率。拟议的工作旨在开发一个采集，重建和显示包的MR监测热消融在移动的器官，如肝脏，能够提供有限的三维覆盖范围的时间分辨率约为1/2秒或更好。提出了一种新的脉冲序列设计和重建策略，专门针对解决MR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灵活的运动跟踪对比度，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，可以优先突出给定的内部特征，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.