MR Temperature Measurements in Fat During MR-Guided HIFU Treatments

MR 引导 HIFU 治疗期间脂肪的 MR 温度测量

• 批准号: 8307201
• 负责人: Nicholas E. Todd
• 金额: $ 4.92万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-30 至 2013-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8307201
• 关键词: Ablation; Adipose tissue; Algorithms; Behavior; Breast; Chemicals; Clinical; Coagulation Process; Computer software; Dependence; Deposition; Development; Drug Delivery Systems; Ensure; Equation; Equilibrium; Evolution; Fatty acid glycerol esters; Focused Ultrasound Therapy; Frequencies; Funding; Goals; Heating; Histocompatibility Testing; Hybrids; Hydrogen; Image; Ionizing radiation; Light; Magnetic Resonance Imaging; Maps; Measurement; Measures; Methods; Modeling; Monitor; Nature; Operative Surgical Procedures; Perfusion; Phase; Physiologic pulse; Problem Solving; Procedures; Process; Protons; Radio; Relaxation; Research; Research Personnel; Research Project Grants; Safety; Site; Spin Labels; System; Techniques; Temperature; Testing; Thermal Conductivity; Thermometry; Time; Tissues; Treatment Efficacy; Tumor Tissue; Ultrasonography; United States National Institutes of Health; Universities; Utah; Validation; Water; Weight; base; density; design; experience; improved; in vivo; microwave electromagnetic radiation; minimally invasive; patient safety; predictive modeling; research study; soft tissue; tumor

DESCRIPTION (provided by applicant): The goal of this project is to overcome the currently unsolved problem of using magnetic resonance imaging (MRI) to measure temperature changes in fat-based tissues. Thermal therapies that use minimally invasive and non-invasive techniques such as radio frequency currents, microwaves, or high intensity focused ultrasound (HIFU) have the potential to revolutionize tumor ablation and drug delivery procedures. Due to the minimally invasive nature of these techniques, constant monitoring of energy deposition and temperature changes are required to ensure treatment efficacy and patient safety. Many investigators have chosen to perform these procedures under MRI guidance because of the improved contrast in soft tissue imaging, the elimination of ionizing radiation, and the ability to measure real time temperature changes in water-based tissues. However, the ability to use MRI for fast, accurate, and robust temperature measurements in fat-based tissues remains an unsolved problem. This limitation represents a large obstacle to the implementation of non- invasive thermal therapies in sites where thermal energy may be deposited in fatty tissue. MR thermometry techniques based on the temperature dependence of the water proton resonant frequency (PRF) are well established and in wide use for water-based tissues, however the method is ineffective in fat- based tissues. To measure temperature changes in fat, investigators have turned to the longitudinal relaxation time, T1, which is temperature dependent for both water- and fat-based tissues. Unfortunately, T1 based temperature measurements are significantly less accurate and stable than PRF temperature measurements in water-based tissues. In light of these challenges, we are taking a two pronged approach to solving the problem of MR temperature measurements in fat. First, the MR sequence will be designed to simultaneously acquire PRF and T1 information. This will allow PRF temperature measurements to be made in all water-based tissues, and T1 temperature measurements to be made in al fat-based tissues. Second, predictions from a thermal model will be incorporated into the process in order to improve the accuracy of the T1 temperature measurements in fat-based tissues. The project will be carried out in four steps. First, we will study the behavior of T1 as a function of temperature in a variety of tissue types. Second, we will develop and optimize the hybrid PRF/T1 sequence. Third, we develop thermal modeling techniques for inhomogeneous tissues. Fourth, we will test and optimize methods for combining the MR temperature measurements with the thermal model temperature predictions.

描述（由申请人提供）：该项目的目标是克服目前尚未解决的使用磁共振成像（MRI）测量脂肪组织温度变化的问题。使用射频电流、微波或高强度聚焦超声 (HIFU) 等微创和无创技术的热疗法有可能彻底改变肿瘤消融和药物输送程序。由于这些技术的微创性质，需要持续监测能量沉积和温度变化，以确保治疗效果和患者安全。许多研究人员选择在 MRI 引导下执行这些手术，因为软组织成像的对比度得到改善，消除了电离辐射，并且能够测量水基组织的实时温度变化。然而，使用 MRI 对脂肪组织进行快速、准确和稳健的温度测量的能力仍然是一个尚未解决的问题。这种限制对于在热能可能沉积在脂肪组织中的部位实施非侵入性热疗法构成了巨大障碍。基于水质子共振频率 (PRF) 温度依赖性的 MR 测温技术已十分成熟，并广泛用于水基组织，但该方法在脂肪组织中无效。为了测量脂肪的温度变化，研究人员转向了纵向弛豫时间 T1，它对于水基组织和脂肪组织都依赖于温度。遗憾的是，基于 T1 的温度测量的准确度和稳定性明显低于基于水的组织中的 PRF 温度测量。鉴于这些挑战，我们正在采取双管齐下的方法来解决脂肪中的 MR 温度测量问题。首先，MR序列将被设计为同时获取PRF和T1信息。这将允许在所有水基组织中进行 PRF 温度测量，并在所有脂肪组织中进行 T1 温度测量。其次，热模型的预测将被纳入该过程中，以提高脂肪组织中 T1 温度测量的准确性。该项目将分四步实施。首先，我们将研究各种组织类型中 T1 作为温度函数的行为。其次，我们将开发和优化混合PRF/T1序列。第三，我们开发了非均匀组织的热建模技术。第四，我们将测试和优化将 MR 温度测量与热模型温度预测相结合的方法。