Cardiac PET/MR: Big footprint—small step?
Cardiac PET/MR: Big footprint—small step?
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心脏 PET/MR：大足迹 — 小进步？
DOI：
--
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发表时间：
2015
影响因子：
2.4
通讯作者：
P. Kaufmann
中科院分区：
文献类型：
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作者：
P. Kaufmann
在医学界，可能没有一项技术发明比威廉·康拉德·伦琴（Wilhelm Conrad Röntgen）在1895年发现的X射线更能改变医学界。伦琴明确表示，他从未申请专利，以促进他的发明的广泛应用。他的发现确实是开创性的，现代医学没有x射线是不可想象的。尽管与伦琴的发明相比，成像领域的许多发展似乎都不那么重要，但如果没有过去几十年的巨大发展，现代成像似乎是不可想象的。虽然放射学的未来似乎是基于新型示踪剂的分子成像，但如果没有过去的技术发展，现在是不可想象的，过去的技术发展的特点是杰出的工程师们气喘吁吁地缩短了缩小技术差距所需的时间跨度，而这些技术差距是由同样气喘吁吁的医学界定义的。随着设备从简单的伽马相机发展到SPECT，PET，最后是混合扫描仪，足迹变得越来越大，这些进步所实现的医学成像步骤大小不一。PET/CT的概念诞生于20世纪90年代初，但直到2001年才宣布了第一个商业临床PET/CT系统，并在此后不久安装在我们的机构。对于肿瘤成像，PET/CT的出现代表了一个突破，使PET单独消失在稀薄的空气中。对于心脏成像，当时在集成CT中可用的4层技术仅允许测试心脏混合PET/CT成像的现代概念的可行性。在SPECT或PET是否代表核心肌灌注成像的未来的问题得到回答之前，另一个发展已经进入临床竞技场-混合PET/MR扫描仪。与PET/CT相比，从概念到实现的道路很长，从技术角度来看，将PET集成到MR中是一项艰巨的挑战，必须解决三个主要问题：首先，经典PET扫描仪中使用的光电倍增管不能在强磁场环境中工作。克服这一问题的策略是在相邻或两个单独的房间中安装具有PET/CT或PET扫描仪和MR扫描仪的顺序系统，通过工作台系统连接，从而导致较大的安装占地面积。最先进的PET/MR设备联合收割机将PET和MR组件物理地结合在具有单个机架的一个扫描仪中，这需要主要的MR硬件重新布置以为PET和对MR扫描仪的磁场较不敏感的现代PET探测器的开发腾出空间。完全集成的系统可缩小占地面积，并允许同时采集PET和MR数据。其次，获得最佳MR图像质量所需的表面线圈可能会导致干扰PET伽马射线的不必要的衰减。最后，与通过CT采集的数据不同，MR数据不容易用于衰减校正。已经提出了解决衰减校正的不同策略，包括基于模板或图谱的方法，或使用MR图像分割和PET发射的方法。因此，为了实现巨大的技术进步，已经进行了巨大的智力努力，这对医学成像的实质性进展寄予了厚望。与PET/CT类似，主要应用已被建议用于非心脏成像，尽管心脏应用被生动地讨论。2015年1月23日，使用术语“心脏PET MR或心肌PET MR”进行PubMed检索，发现了274篇文章。快速浏览一下就会发现，真正涉及心脏PET/MR成像的文章不到10%。虽然许多综述文章描述了心脏PET/MR具有重要临床作用的巨大潜力和光明前景，但没有研究要求重印：Philipp A Kaufmann，MD，FESC，FSCCT，Department of Nuclear Medicine，University Hospital苏黎世，Ramistr。100（NUK D 6），8091苏黎世，瑞士; pak@usz.ch J Nucl Cardiol 2015;22：225-6。1071-3581/$34.00版权所有2015美国核心脏病学会。
There is probably no technical invention which has changed more within the medical world than the discovery of the x-rays by Wilhelm Conrad Röntgen in 1895 who explicitly never filed a patent in order to facilitate the widespread availability of his invention. His discovery was indeed groundbreaking, and modern medicine is unthinkable without x-rays. Although most of the many developments in the field of imaging appear to be of modest importance compared to Röntgens invention, modern imaging seems unthinkable without the tremendous developments of the last decades. While the future of Radiology seems to be in molecular imaging based on novel tracers, the present is unimaginable without the past technical evolution which was characterized by brilliant engineers who have breathlessly shortened the time spans needed for closing technological gaps defined by an equally breathless medical community. As the footprints got bigger with the devices growing from simple gamma cameras to SPECT, PET, and finally hybrid scanners, the steps in medical imaging achieved by these advancements were of variable size. The concept of PET/CT was born in the early 1990s, but only in 2001 the first commercial clinical PET/CT system was announced and shortly thereafter installed in our institution. For oncology imaging, the advent of PET/CT represented a breakthrough, causing PET alone to vanish in thin air. For cardiac imaging, the 4-slice technique available at that time in the integrated CT did not allow more than testing the feasibility of a modern concept for cardiac hybrid PET/CT imaging. Before the question whether SPECT or rather PET may represent the future of nuclear myocardial perfusion imaging was ever answered, another development has entered the clinical arena— the hybrid PET/MR scanner. Comparable to PET/CT, the way from concept to realization was long and from a technical point of view, the integration of PET into an MR was a formidable challenge with three main problems which had to be solved: First, the photomultipliers used in the classic PET scanners do not work in an environment with strong magnetic fields. A strategy to overcome this was the installation of a sequential system with PET/CT or PET scanner and an MR scanner adjacent or in two separate rooms, joined by a table system resulting in large installation footprints. The most advanced PET/MR devices combine the PET and MR components physically in one scanner with a single gantry which required major MR hardware rearrangements to make room for the PET and development of modern PET detectors less sensitive to the MR scanner’s magnetic fields. Fully integrated systems result in smaller footprints and allow for the simultaneous acquisition of PET and MR data. Second, surface coils needed to get best MR image quality can cause unwanted attenuation interfering with the gamma rays from PET. Finally, MR data, unlike those acquired by CT, are not readily usable for attenuation correction. Different strategies to address attenuation correction have been suggested including templateor atlas-based methods, or approaches using MR image segmentation and PET emission. Thus, tremendous intellectual efforts have been done for achieving a big technical progress which has raised high hopes for substantial steps of progress in medical imaging. Similar to PET/CT, the main applications have been suggested for non-cardiac imaging, although cardiac applications are vividly discussed. A PubMed search with the terms ‘‘cardiac PET MR or myocardial PET MR’’ revealed 274 articles on January 23, 2015. A quick look reveals that much less than 10% of these articles really deal with integrated cardiac PET/MR imaging. While numerous review articles describe the great potential and the bright future perspectives of cardiac PET/MR with an important clinical role, no studies are Reprint requests: Philipp A Kaufmann, MD, FESC, FSCCT, Department of Nuclear Medicine, University Hospital Zurich, Ramistr. 100 (NUK D 6), 8091 Zurich, Switzerland; pak@usz.ch J Nucl Cardiol 2015;22:225–6. 1071-3581/$34.00 Copyright 2015 American Society of Nuclear Cardiology.
DOI：
10.1053/j.sult.2008.05.006
发表时间：
2008-08
期刊：
Seminars in ultrasound, CT, and MR
影响因子：
--
作者：
Townsend DW
通讯作者：
Townsend DW