Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University Tuebingen, Tuebingen, Germany.
Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University Tuebingen, Tuebingen, Germany; Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard Karls University Tuebingen, Tuebingen, Germany.
Semin Nucl Med. 2018 Jul;48(4):332-347. doi: 10.1053/j.semnuclmed.2018.02.011. Epub 2018 Apr 10.
Over the last decade, the combination of PET and MRI in one system has proven to be highly successful in basic preclinical research, as well as in clinical research. Nowadays, PET/MRI systems are well established in preclinical imaging and are progressing into clinical applications to provide further insights into specific diseases, therapeutic assessments, and biological pathways. Certain challenges in terms of hardware had to be resolved concurrently with the development of new techniques to be able to reach the full potential of both combined techniques. This review provides an overview of these challenges and describes the opportunities that simultaneous PET/MRI systems can exploit in comparison with stand-alone or other combined hybrid systems. New approaches were developed for simultaneous PET/MRI systems to correct for attenuation of 511 keV photons because MRI does not provide direct information on gamma photon attenuation properties. Furthermore, new algorithms to correct for motion were developed, because MRI can accurately detect motion with high temporal resolution. The additional information gained by the MRI can be employed to correct for partial volume effects as well. The development of new detector designs in combination with fast-decaying scintillator crystal materials enabled time-of-flight detection and incorporation in the reconstruction algorithms. Furthermore, this review lists the currently commercially available systems both for preclinical and clinical imaging and provides an overview of applications in both fields. In this regard, special emphasis has been placed on data analysis and the potential for both modalities to evolve with advanced image analysis tools, such as cluster analysis and machine learning.
在过去的十年中，将 PET 和 MRI 组合在一个系统中已被证明在基础临床前研究以及临床研究中非常成功。如今，PET/MRI 系统在临床前成像中已得到广泛应用，并正在向临床应用推进，以提供对特定疾病、治疗评估和生物学途径的更深入了解。在开发新技术的同时，必须解决某些硬件方面的挑战，才能充分发挥这两种技术的潜力。本文综述了这些挑战，并描述了与独立或其他组合式混合系统相比，同时进行 PET/MRI 系统可以利用的机会。同时进行 PET/MRI 系统开发了新方法来校正 511keV 光子的衰减，因为 MRI 无法直接提供伽马光子衰减特性的信息。此外，还开发了新的运动校正算法，因为 MRI 可以以高时间分辨率准确检测运动。MRI 获得的附加信息也可用于校正部分容积效应。结合快速衰减闪烁晶体材料的新型探测器设计的发展，使飞行时间检测和纳入重建算法成为可能。此外，本文列出了目前临床前和临床成像的商业上可用的系统，并概述了这两个领域的应用。在这方面，特别强调了数据分析以及两种模式与高级图像分析工具（如聚类分析和机器学习）一起发展的潜力。
