Two-dimensional ultrashort echo time imaging using a spiral trajectory
Two-dimensional ultrashort echo time imaging using a spiral trajectory
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DOI：
10.1016/j.mri.2007.08.005
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发表时间：
2008-04-01
影响因子：
2.5
通讯作者：
Chung, Christine B.
中科院分区：
文献类型：
--
作者：
Du, Jiang;Bydder, Mark;Chung, Christine B.
由于激发的MR信号的快速衰减，具有非常短的横向弛豫时间（T2）的组织不能使用常规的磁共振（MR）序列来检测。在这项工作中，采用半脉冲激励和螺旋采样的多回波序列开发的超短回波时间（UTE）成像的组织与短T2。螺旋读出梯度进行测量和预补偿，以减少梯度失真，由于涡流和梯度各向异性。通过对不同螺旋采样时间的橡皮筋进行螺旋UTE（SUTE）成像，实验研究了由于信号快速衰减而引起的空间模糊效应。通过使用反转脉冲和调零和/或从初始回波图像中减去后续回波图像来抑制不需要的长T2信号。该技术已应用于正常人脑白色物质、膝关节软骨、骨和颈动脉血管壁在1.5T下的短T2分量成像。初步结果表明，在相对较短的扫描时间下，人体内各种短T2组织的空间分辨率高，图像对比度好。定量比较径向UTE和SUTE之间的信噪比效率。(c)2008年爱思唯尔公司All rights reserved.
Tissues with very short transverse relaxation time (T2) cannot be detected using conventional magnetic resonance (MR) sequences due to the rapid decay of excited MR signals. In this work, a multiecho sequence employing half-pulse excitation and spiral sampling was developed for ultrashort echo time (UTE) imaging of tissues with short T2. Spiral readout gradients were measured and precompensated to reduce gradient distortions due to eddy currents and gradient anisotropy. The effects of spatial blurring due to fast signal decay were investigated experimentally through spiral UTE (SUTE) imaging of rubber bands with different spiral sampling duration. The unwanted long T2 signals were suppressed through the use of an inversion pulse and nulling, and/or subtraction of a later echo image from the initial one. This technique has been applied to imaging of the short T2 components in brain white matter, knee cartilage, bone and carotid vessel wall of normal volunteers at 1.5 T. Preliminary results show high spatial resolution and excellent image contrast for a variety of short T2 tissues in the human body under a relatively short scan time. A quantitative comparison was also made between radial UTE and SUTE in terms of signal-to-noise ratio efficiency. (c) 2008 Elsevier Inc. All rights reserved.