Image quality of PET reconstructions is degraded by subject motion occurring during the acquisition. MR-based motion correction approaches have been studied for PET/MR scanners and have been successful at capturing regular motion patterns, when used in conjunction with surrogate signals (e.g. navigators) to detect motion. However, handling irregular respiratory motion and bulk motion remains challenging. In this work, we propose an MR-based motion correction method relying on subspace-based real-time MR imaging to estimate motion fields used to correct PET reconstructions. We take advantage of the low-rank characteristics of dynamic MR images to reconstruct high-resolution MR images at high frame rates from highly undersampled k-space data. Reconstructed dynamic MR images are used to determine motion phases for PET reconstruction and estimate phase-to-phase nonrigid motion fields able to capture complex motion patterns such as irregular respiratory and bulk motion. MR-derived binning and motion fields are used for PET reconstruction to generate motion-corrected PET images. The proposed method was evaluated on in vivo data with irregular motion patterns. MR reconstructions accurately captured motion, outperforming state-of-the-art dynamic MR reconstruction techniques. Evaluation of PET reconstructions demonstrated the benefits of the proposed method over standard methods in terms of motion artifact reduction. The proposed method can improve the image quality of motion-corrected PET reconstructions in clinical applications.
An efficient approach with theoretical guarantees to simultaneously reconstruct activity and attenuation sinogram for TOF-PET
State Key Laboratory of Mathematical Sciences, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190, China（数学科学国家重点实验室，数学与系统科学研究院，中国科学院，北京100190，中国）；University of Chinese Academy of Sciences, Beijing 100190, China（中国科学院大学，北京100190，中国）
Multibranch Generative Models for Multichannel Imaging with an Application to PET/CT Synergistic Reconstruction
Univ. Brest, LaTIM, INSERM, UMR 1101（布雷斯特大学、LaTIM研究所、法国国家健康与医学研究院、UMR 1101联合研究单位）；Nuclear Medicine Department, Poitiers University Hospital（普瓦捷大学医院核医学科）
A novel TOF-PET MRI detector for diagnosis and follow up of the prostate cancer
前列腺癌是男性最常见的疾病，也是癌症死亡的第二大原因。用于癌症诊断的通用大型成像仪器具有灵敏度、空间分辨率和对比度，不足以完成对诸如前列腺的小器官的细节进行成像的任务。此外，多模态成像可以发挥重要作用，合并来自同步PET和MRI的解剖和功能细节。事实上，多参数PET/MRI被证明可以提高诊断，但它有太多的假阳性。为了解决当前技术的上述限制，我们已经提出，建立和测试，由于TOPEM项目由意大利国家核物理研究所资助的直肠内PET-TOF/MRI探头的原型。在应用的放大PET几何结构中，性能由放置在更靠近源的高分辨率探测器主导。所选几何结构中的预期空间分辨率约为1.5 mm FWHM，效率为常规PET扫描仪的2倍。在我们的实验研究中，我们已经获得了约320 ps的FWHM的时间分辨率，并在同一时间的相互作用深度（DOI）的分辨率为1毫米以下。测试还表明，相互不利的PET-MR效应是最小的。此外，还设计、制造和测试了匹配的直肠内射频线圈。在接下来计划的研究中，我们希望受益于闪烁体晶体表面处理、SiPM技术和相关电子学的进一步进展，将使我们能够显著提高TOF分辨率
High-resolution Time-Of-Flight PET with Depth-Of-Interaction becomes feasible: a proof of principle
在本文中，我们证明了闪烁体表面的适当处理的选择，以及用于原始数据分析的适当光电探测器电子器件和特定算法，允许实现能量、时间和DOI分辨率之间的最佳权衡，从而强烈支持具有所需特征和性能的前列腺TOF-PET探针的可行性，所述探针与MRI兼容。在数量上，这意味着1.5mm x 1.5mm x 10 mm的探测器元件，同时实现约11.5%的能量分辨率、约150 ps的飞行时间分辨率和甚至低于1 mm的DOI分辨率。我们强调，这样的时间分辨率允许显著增加噪声等效计数率，从而提高图像质量和病变检测能力。这些个别值对应于其他小组迄今为止获得的最佳值，但我们同时获得了所有这些值。在我们看来，这一原理证明为具有前所未有的功能和性能的TOF-PET MRI兼容探头的可行性铺平了道路，不仅是前列腺放射性示踪剂成像的创新，而且可能也适用于其他器官。
Omni-tomography/Multi-tomography -- Integrating Multiple Modalities for Simultaneous Imaging
Virginia Tech（弗吉尼亚理工大学）；Wake Forest University（维克森林大学）；University of Minnesota（明尼苏达大学）；University of California, Los Angeles（加利福尼亚大学洛杉矶分校）；Baylor University Medical Center（贝勒大学医学中心）；Texas Instruments Inc.（德州仪器公司）；University of Chicago（芝加哥大学）
