MR IMAGING TECHNIQUES FOR INTERVENTIONAL APPLICATIONS

MR引导治疗对动态MRI方法有特殊的要求。 首先，可以连续地选择图像视场(FOV 医生使用例如指点设备来改变方式。 第二，与成像平面的选择无关， 图像FOV本身可以在物理上改变(例如，作为活检 针头进入)或化学(例如，在激光或射频消融期间，或作为 注射造影剂团块)，从而改变所得到的MR 图像。所有这些情况都需要动态磁共振成像方法。 动态MRI与标准MRI的不同之处在于，动态MRI的时间序列 通过不断更新或重新获取图像数据来获得图像。 我们实验室最近的研究集中在新的动态 磁共振引导治疗过程中的自适应成像方法 进化得如此之快，以至于它们不能同时得到充分的解决 使用当前的动态方法在空间和时间上。动态地 自适应方法被区分为图像数据 根据信息动态修改采集策略 经过处理后获得的最近获取的图像(S)。 我们的方法建立在这样的假设基础上，即 在不损失图像质量的情况下，时间分辨率可以在 使用自适应方法最小化图像冗余的动态MRI 编码和数据采集。正在研究的磁共振成像方法在 我们的实验室，都是高效的编码和采集方法。他们可以 在快速成像技术的背景下实现(例如，回声 平面或快速梯度回波)，其不利用数据中的冗余 收购。 我们将重点实施和改进三个主要的动态MRI 方法： A.小波变换编码技术； B.奇异值分解(SVD)编码技术； C.专门的傅里叶变换编码技术。 我们还将根据标准性能对每种方法进行评估 标准(信噪比、空间和时间分辨率)。 最后，我们将研究选择性射频激励方法的物理特性 MRI(每种成像方法的基础)和诊断实用程序 使用改进的标准ROC方法来评估检测的新方法 以及表征一系列图像中的时变信息。 该方法开发项目将通过以下方式对计划产生影响 提供更高的空间和时间分辨率、更快(动态) 对空间相关信息进行扫描和量化，以 其他四个项目的具体目标。

MR guided therapy has a specific requirement for dynamic MRI methods. First, the image field-of-view (FOV) may be selected in a continuously varying fashion by physician using, for example, a pointing device. Second, independent of the selection of the imaging plane, the objects in the image FOV may themselves be changing physically (e.g., as a biopsy needle enters) or chemically (e.g., during laser or rf ablation, or as a bolus of contrast agent is injected) therefore altering the resultant MR image. All of these circumstances require a dynamic MR imaging method. Dynamic MRI differs from standard MRI in that a sequence of time-ordered images is obtained by continually updating or reacquiring image data. Recent investigations of our laboratory have focused on new dynamically adaptive methods for imaging the processes involved in MR guided therapy that evolve so rapidly that they cannot be adequately resolved both spatially and temporally using current dynamic approaches. Dynamically adaptive methods are distinguished as those in which the image data acquisition strategy is modified dynamically depending on information obtained after processing the most recently acquired image(s). Our approach is founded on the hypothesis that significant improvement in temporal resolution, without loss of image quality, can be obtained in dynamic MRI if an adaptive method is used to minimize redundancy in image encoding and data acquisition. The MRI methods that are under study in our laboratory, are efficient encoding and acquisition methods. They can be implemented in the context of fast imaging techniques (e.g., echo- planar or fast gradient-echo), which do not exploit redundancy in data acquisition. We will focus on implementing and improving three main dynamic MRI approaches: a. Wavelet transform encoding techniques; b. SVD (Singular Value Decomposition) encoding techniques; c. Specialized Fourier transform encoding techniques. We will also evaluate each method in terms of standard performance criteria (signal-to-noise ratios, spatial and temporal resolution). Finally, we will study the physics of selective rf excitation methods for MRI (the basis of each of the imaging methods) and the diagnostic utility of new methods using standard ROC methods modified to assess the detection and characterization of time-varying information in series of images. This method development project will have an impact on the program by providing improved spatial and temporal resolution, faster (dynamic) scanning, and quantitation of spatially dependent information tailored to the specific goals of each of the other four projects.