Improved MRI temperature imaging using a subject-specific biophysical model

描述(由申请人提供)：该项目的目标是通过显著扩展高强度聚焦超声(HIFU)目前的空间和时间分辨率以及视野(FOV)能力，改进用于高强度聚焦超声(HIFU)热疗的磁共振温度成像(MRTI)技术。这些改进将克服经颅MRI引导的聚焦超声治疗的速度、分辨率和视野障碍，从而加速该技术进入临床实践的接受。为了实现这一目标，我们建议开发一种全新的MRTI方法，该方法通过在每个时间帧中对测量空间(k空间)进行二次采样来提高速度，并且使用结合了非均匀组织的生物热和声学属性的特定对象的生物物理模型来动态(实时)预测丢失的测量。这种方法的独特之处在于，它用额外的特定于对象的生物物理信息补充了3D MRTI。我们将这种方法称为模型预测滤波(MPF)，因为它类似于其他线性预测滤波，如卡尔曼滤波。这项新的MPF技术将实现对足够大的区域的温度分布进行所需的准确、精确和快速的高分辨率测量，从而有效地实时监测和控制处理。这项工作将分三个阶段开发改进温度测量的方法：1)首先，将开发一种时间约束重建(TCR)技术，以获得在感兴趣体积上具有高空间和时间分辨率的回顾性MRTI测量结果。2)TCR温度结合组织分割和波束建模将被用于确定特定于受试者的3D组织声学和热学特性。3)将组织的声学和热学特性结合到MPF技术中，以实时获得所需的全辐射体积上的温度图像。然后，这些方法将在动物模型中进行体内测试，并在经颅MRgHIFU系统中进行体外和体外测试。经颅脑MRgHIFU是一项重要的应用，需要开发创新的治疗策略，并肯定需要对整个辐照体积进行快速、准确、高空间分辨率的温度测量。这些技术非常新颖，一旦成功，将促进实验加速接受经颅大脑MRgHIFU以及潜在的其他新的MRgHIFU应用。

DESCRIPTION (provided by applicant): The goal of this project is to improve magnetic resonance temperature imaging (MRTI) techniques to be used in high intensity focused ultrasound (HIFU) thermal treatments by significantly expanding their current spatial and temporal resolution and field of view (FOV) capabilities. These improvements will overcome the speed, resolution, and FOV roadblocks in transcranial MRI guided focused ultrasound therapy and thereby accelerate the acceptance of this technique into clinical practice. To realize this goal we propose to develop a completely new MRTI approach that increases speed by subsampling the measurement space (k-space) in each time frame and that uses a subject-specific biophysical model incorporating inhomogeneous tissue biothermal and acoustic properties to dynamically (in real-time) predict the missing measurements. The uniqueness of this approach is that it supplements 3D MRTI with additional subject-specific biophysical information. We refer to this method as model predictive filtering (MPF) because it is similar to other linear predictive filters, such as the Kalman filter. This new MPF technique will achieve the required accurate, precise, and rapid high-resolution measurements of temperature distributions over regions sufficiently large to effectively monitor and control treatments in real-time. The work will develop methods to improve temperature measurements in three stages: 1) First a temporally-constrained reconstruction (TCR) technique will be developed to obtain retrospective MRTI measurements with high spatial and temporal resolution over the volume of interest. 2) The TCR temperatures combined with tissue segmentation and beam modeling will be used to determine 3D subject- specific tissue acoustic and thermal properties. 3) The tissue acoustic and thermal properties will be incorporated into the MPF technique to obtain the desired temperature images over the full insonified volume in real-time. These methods will then be tested in vivo in animal models and in vitro and ex vivo in a transcranial MRgHIFU system. Transcranial brain MRgHIFU is an important application that requires the development of innovative treatment strategies and will definitely require rapid, accurate, high spatial resolution temperature measurements over the entire insonified volume. These techniques are highly novel, and upon success will facilitate experiments to accelerate the acceptance of transcranial brain MRgHIFU as well as potentially other new MRgHIFU applications.