Padormo Francesco, Beqiri Arian, Hajnal Joseph V, Malik Shaihan J
Department of Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St Thomas' Hospital, London, UK.
Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St Thomas' Hospital, London, UK.
NMR Biomed. 2016 Sep;29(9):1145-61. doi: 10.1002/nbm.3313. Epub 2015 May 19.
The development of MRI systems operating at or above 7 T has provided researchers with a new window into the human body, yielding improved imaging speed, resolution and signal-to-noise ratio. In order to fully realise the potential of ultrahigh-field MRI, a range of technical hurdles must be overcome. The non-uniformity of the transmit field is one of such issues, as it leads to non-uniform images with spatially varying contrast. Parallel transmission (i.e. the use of multiple independent transmission channels) provides previously unavailable degrees of freedom that allow full spatial and temporal control of the radiofrequency (RF) fields. This review discusses the many ways in which these degrees of freedom can be used, ranging from making more uniform transmit fields to the design of subject-tailored RF pulses for both uniform excitation and spatial selection, and also the control of the specific absorption rate. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.
7特斯拉及以上运行的磁共振成像（MRI）系统的发展为研究人员提供了一扇观察人体的新窗口，带来了更高的成像速度、分辨率和信噪比。为了充分实现超高场MRI的潜力，必须克服一系列技术障碍。发射场的不均匀性就是其中一个问题，因为它会导致具有空间变化对比度的不均匀图像。并行传输（即使用多个独立传输通道）提供了以前无法获得的自由度，从而能够对射频（RF）场进行全面的空间和时间控制。本文综述了这些自由度的多种使用方式，从生成更均匀的发射场到设计用于均匀激发和空间选择的个性化RF脉冲，以及特定吸收率的控制。© 2015作者。《生物医学中的核磁共振》由约翰·威利父子有限公司出版
