Novel Quantitation Approaches of PET & MR Signals

现代全身PET扫描仪的固有空间分辨率约为4 mm。然而， 心脏或腹部PET成像的实际可达到的分辨率可能低于10 mm 由于不可避免的心脏和呼吸运动。头部运动产生的运动伪影也是 脑部正电子发射计算机断层扫描的主要障碍。我们的工作将允许在免费的动态和静态成像- 患者在呼吸的同时实现了PET的固有分辨率。这片土地- 打破(X2)空间分辨率的改进将在保留的同时实现，或者有时 PET的灵敏度越来越高，这在医学成像中是相当不寻常的。重要的一点是 显著提高了精度、空间分辨率(即从~10 mm提高到~4 mm)和灵敏度 由这项研发实现的PET无论怎么强调都不为过，因为它将对 许多临床应用，包括：(1)揭示肿瘤的异质性(例如，坏死核)，(2) 对小肺肿瘤进行成像，(3)检测非跨壁心肌缺陷，以及(4)分期和 使用tau的高分辨率PET成像监测阿尔茨海默病的治疗反应。至 为了实现这一目标，我们提出了一种新颖的基于MR的PET运动校正和精确/运动校正。 使用PET/MR的依赖的PET衰减校正方法具体地，对于常规的非 飞行时间PET/MR，我们建议使用一种新的自由呼吸ZTE/多回波序列来获得 肺、骨、脂肪和软组织的连续衰减系数图。关于飞行时间的 PET/MR，我们提出了活度和衰减校正的最大后验估计 TOF-PET数据稳健衰减系数估计的MAPAACF方法。我们 提出了新颖、准确的基于MR的运动估计和跟踪方法 具有刚性或非刚性运动的不同器官。最后，我们提出了一种新的低阶张量-- 基于MR的加速方法，捕获多维数据相关性以显著 减少磁共振成像时间。

The intrinsic spatial resolution of modern whole-body PET scanners is about 4 mm. However, the practically achievable resolution of cardiac or abdominal PET imaging may be worse than 10 mm due to inevitable cardiac and respiratory motion. Motion artifacts from head motion are also one of the major hurdles in brain PET. Our work will allow dynamic as well as static imaging in the free- breathing patient while at the same time achieving the intrinsic resolution of PET. This ground- breaking (x2) improvement in spatial resolution will be accomplished while preserving, or sometimes increasing, the sensitivity of PET, which is quite unusual in medical imaging. The importance of the significantly improved accuracy, spatial resolution (i.e., from ~10 mm to ~4 mm) and sensitivity in PET enabled by this TR&D cannot be over emphasized because it will have significant impacts on many clinical applications, including: (1) revealing tumor heterogeneity (e.g., necrotic core), (2) imaging small lung tumors, (3) detecting non-transmural myocardial defects, and (4) staging and monitoring response to therapy in Alzheimer's disease using high-resolution PET imaging of tau. To achieve this goal, we propose novel MR-based PET motion correction and accurate/motion- dependent PET attenuation correction methods using PET/MR. Specifically, for conventional non- time-of-flight PET/MR, we propose to use a novel free-breathing ZTE/multi-echo sequence to obtain continuous attenuation coefficient maps of lungs, bones, fat and soft tissues. For the time-of-flight PET/MR, we propose a maximum a posteriori estimation of activity and attenuation correction factors (MAPAACF) method for robust attenuation coefficient estimation from TOF-PET data. We also propose novel and accurate MR-based motion estimation and tracking methods for imaging different organs with either rigid or non-rigid motion. Finally, we propose a novel low-rank tensor- based MR acceleration method that captures data correlation in multiple dimensions to significantly reduce MR imaging time.