磁共振成像技术：揭示隐形的世界

English | 2024 | ISBN-10: 3031351967 | 638 pages| PDF (True) | 66 MB

This book comprehensively covers ultrashort echo time (UTE), zero echo time (ZTE), and other magnetic resonance imaging (MRI) acquisition techniques for imaging of short and ultrashort-T2 tissues. MRI uses a large magnet and radio waves to generate images of tissues in the body. The MRI signal is characterized by two time constants, spin-lattice relaxation time (T1) which describes how fast the longitudinal magnetization recovers to its initial value after tipping to the transverse plane, and spin-spin relaxation time (T2) which describes how fast the transverse magnetization decays. Conventional MRI techniques have been developed to image and quantify tissues with relatively long T2s. However, the body also contains many tissues and tissue components such as cortical bone, menisci, ligaments, tendons, the osteochondral junction, calcified tissues, lung parenchyma, iron containing tissues, and myelin, which have short or ultrashort-T2s. These tissues are “invisible” with conventional MRI, and their MR and tissue properties are not measurable. UTE and ZTE type sequences resolve these challenges and make these tissues visible and quantifiable.

This book first introduces the basic physics of conventional MRI as well as UTE and ZTE type MRI, including radiofrequency excitation, data acquisition, and image reconstruction. A series of contrast mechanisms are then introduced and these provide high resolution, high contrast imaging of short and ultrashort-T2 tissues. A series of quantitative UTE imaging techniques are described for measurement of MR tissue properties (proton density, T1, T2, T2*, T1p,magnetization transfer, susceptibility, perfusion and diffusion). Finally, clinical applications in the musculoskeletal, neurological, pulmonary and cardiovascular systems are described.

这本书全面涵盖了超短回波时间（UTE）、零回波时间（ZTE）以及其他磁共振成像（MRI）技术，用于对短T2和极短T2组织的成像。MRI利用一个大型磁场和无线电波生成体内的组织图像。MRI信号由两个时长常数表示：自旋-晶格弛豫时间（T1），描述了当向横向平面倾斜后，纵向磁化率恢复到初始值所需的时间；自旋-自旋弛豫时间（T2），描述了横向磁化衰减的速度。常规的MRI技术已发展用于成像和量化相对长T2的组织。然而，人体中也有很多包含冠状骨、半月板、韧带、肌腱、关节软骨面、钙化的组织、肺实质、含铁组织以及髓鞘等含有短或极短T2的组织。这些组织对常规MRI是“隐形”的，其MR和组织特性无法测量。UTE和ZTE类型的序列解决了这些问题，并使这些组织变得可见且可量化。 本书首先介绍了常规MRI以及UTE和ZTE类型MRI的基本物理，包括射频激发、数据采集及图像重建。然后介绍了一系列的对比机制，这些机制提供了对短T2和极短T2组织进行高分辨率高对比度成像的能力。书中描述了一系列表观密度测量技术、T1、T2、T2*、磁化转移率（magnetization transfer）、敏感性、灌注以及扩散等MR组织特性的量化UTE成像技术。最后，描述了这些技术在肌肉骨骼系统、神经系统、肺部和心血管系统的临床应用。

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