Integrated Magnetic Resonance Imaging for Radiation Therapy Applications

***放射治疗在很大程度上依赖于成像信息来制定治疗计划、剂量预测和放射传递。MRI提供的软组织对比和成像灵活性可以极大地影响这一过程。该计划的长期目标是为放射治疗提供一种综合MRI方法，以实现强大的解剖和生理成像。我们的研究将为临床医生提供更好的对比，以获得准确的轮廓，用于剂量计算的组织类型信息，以及指导治疗决策的稳健的生理测量，并进一步实现基于mri的计划。基于多回波梯度回波（MGRE）序列的T1-和T2*加权成像，开发一种优化的结构MR成像方法，为组织解剖量身定制体内成像，用于RT规划，并将衍生的T2*对比度与常规T2对比度进行病变和器官描绘的比较***2。设计、实施和验证一种MRI方法，基于磁化率图稳健地描绘主要组织类别（软组织、骨骼、空气），以克服传统MRI在缺乏水信号区域的局限性。* * * 3。使用DCE MRI开发一种实用的生理成像方法，用于RT计划过程，具有快速，鲁棒的模式识别（PR）为基础的分析。我们将共同设计数据采集、图像重建和分析***科学方法***体积多回波梯度回波成像将是这种针对RT治疗计划量身定制的体内成像方法的基础。多对比解剖成像将以器官描绘和病变识别为目标。基于磁导率的空气、骨骼和软组织信息重建结合组织属性分配将被研究作为x射线非均质信息计算剂量的方法。对比基于模型的灌注指标作为肿瘤生理学的标志物，并评估一种实用且稳健的对比增强灌注MRI方法，并评估剂量调节。该方法的所有组成部分都旨在共享数据，并使整个过程更加有效。我们的学术单位在放射肿瘤学实践的整合将是关键调查的关键方面，可以影响规划和模拟工作流程。***新颖性和意义***磁共振成像将潜在地改变多种癌症的放疗模拟、计划、交付和治疗评估。这种MRI方法的软组织对比和生理信息将影响RT计划、治疗决策和评估。我们的综合方法将为基于图像的RT治疗计划提供必要的信息，并在临床RT环境中产生可行的基于mr的模拟和实用的随访成像

Introduction*** Radiation therapy relies heavily on imaging information for treatment planning, dose prediction, and radiation delivery. The soft tissue contrast and imaging flexibility provided by MRI can greatly impact this process. The long-term goal of this program is an integrated MRI approach to robust anatomical and physiological imaging for radiation therapy. Our research will provide improved contrast to clinicians for accurate contouring, tissue type information for dose calculations, and robust physiological measures to guide treatment decisions, and further enable MRI-based planning.***Aims***1. Develop an optimized structural MR imaging approach for tailored in vivo imaging of tissue anatomy for RT planning, based on a multi-echo gradient echo (MGRE) sequence for T1- and T2*-weighted imaging, and compare the derived T2* contrast to conventional T2 contrast for lesion and organ delineation***2. Design, implement and validate an MRI approach to robustly delineate the major tissue categories (soft tissue, bone, air) based on magnetic susceptibility mapping, to overcome the limitations of conventional MRI in areas lacking water signal. ***3. Develop a practical physiological imaging method for the RT planning process using DCE MRI, with fast, robust pattern-recognition (PR)-based analysis. We will jointly design data acquisition, image reconstruction and analysis***Scientific Approach*** Volumetric multi-echo gradient echo imaging will be the foundation of this in vivo imaging approach tailored to RT treatment planning. Multi-contrast anatomical imaging will target organ delineation and lesion identification. Magnetic-susceptibility-based reconstruction of air, bone, and soft tissue information combined with tissue property assignment will be investigated as an approach to X-ray heterogeneity information for dose calculation. A practical and robust approach for contrast-enhanced perfusion MRI will be evaluated, compared to model-based perfusion metrics as a marker of tumor physiology, and evaluated for dose modulation. All components of the approach will be designed to share data and to make the entire process more efficient. The integration of our academic unit in the radiation oncology practice will be key to investigate critical aspects that can impact the planning and simulation workflow.***Novelty and Significance*** MR imaging will potentially transform RT simulation, planning, delivery, and treatment assessment for a number of cancers. The soft tissue contrast and physiological information from this MRI approach will impact RT planning, treatment decisions, and assessment. Our integrated approach will provide the necessary information for image-based RT treatment planning, and result in feasible MR-based simulation and practical follow-up imaging in the clinical RT context.**