School of Biomedical Engineering, College of Biomedical and Health Science, Research Institute of Biomedical Engineering, Konkuk University, Chungju, Korea (ROK).
Magn Reson Med. 2012 Feb;67(2):428-36. doi: 10.1002/mrm.23026. Epub 2011 Jun 23.
Ultrashort echo-time imaging and sweep imaging with Fourier transformation are powerful techniques developed for imaging ultrashort T(2) species. However, it can be challenging to implement them on standard clinical MRI systems due to demanding hardware requirements. In this article, the limits of what is possible in terms of the minimum echo-time and repetition time with 3D radial gradient-echo sequences, which can be readily implemented on a standard clinical scanner, are investigated. Additionally, a new 3D radial gradient-echo sequence is introduced, called COncurrent Dephasing and Excitation (CODE). The unique feature of CODE is that the initial dephasing of the readout gradient is performed during RF excitation, which allows CODE to effectively achieve echo-times on the order of ∼0.2 ms and larger in a clinical setting. The minimum echo-time achievable with CODE is analytically described and compared with a standard 3D radial gradient-echo sequence. CODE was implemented on a clinical 3 T scanner (Siemens 3 T MAGNETOM Trio), and both phantom and in vivo human knee images are shown for demonstration.
超短回波时间成像和傅里叶变换扫频成像是用于成像超短 T(2)物质的强大技术。然而，由于硬件要求苛刻，在标准的临床 MRI 系统上实现这些技术具有挑战性。在本文中，研究了可以在标准临床扫描仪上轻松实现的 3D 径向梯度回波序列的最小回波时间和重复时间的限制。此外，还介绍了一种新的 3D 径向梯度回波序列，称为同时去相位和激发（CODE）。CODE 的独特之处在于在 RF 激发期间执行读出梯度的初始去相位，这使得 CODE 能够在临床环境中有效地实现约 0.2 ms 及更大的回波时间。分析描述了 CODE 可实现的最小回波时间，并与标准的 3D 径向梯度回波序列进行了比较。CODE 已在临床 3T 扫描仪（西门子 3T MAGNETOM Trio）上实现，并展示了用于演示的体模和体内人膝关节图像。
