Dual inversion recovery, ultrashort echo time (DIR UTE) imaging: creating high contrast for short-T(2) species.
Dual inversion recovery, ultrashort echo time (DIR UTE) imaging: creating high contrast for short-T(2) species.
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DOI：
10.1002/mrm.22257
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发表时间：
2010-02
影响因子：
3.3
通讯作者：
Bydder GM
中科院分区：
文献类型：
--
作者：
Du J;Takahashi AM;Bae WC;Chung CB;Bydder GM
短T2核素的成像不仅需要短回波时间（TE），而且需要有效抑制长T2核素，以最大化短T2对比度和动态范围。本文介绍了一种利用两个绝热反转长脉冲抑制长T2的方法。第一个绝热反转脉冲反转长T2水的磁化，第二个绝热反转脉冲反转脂肪的磁化。短T2物种经历了一个显着的横向弛豫在长绝热反转过程中，并最小限度地受反转脉冲。8 μs短TE的数据采集在TI1的时间延迟后开始，以使反转水磁化达到零点，并在TI2的时间延迟后开始，以使反转脂肪磁化达到零点。长T_2核素的抑制依赖于T_1、T_2和TR的适当组合。由于绝热反转脉冲，它对RF不均匀性不敏感。使用临床3T扫描仪在体模、尸体标本和健康志愿者上证明了这种双反转恢复超短TE（ENUTE）技术的可行性。关节软骨、皮质骨和跟腱的深层放射状和钙化层实现了高图像对比度。
Imaging of short-T2 species requires not only a short echo time (TE) but also efficient suppression of long-T2 species in order to maximize the short-T2 contrast and dynamic range. This paper introduces a method of long-T2 suppression using two long adiabatic inversion pulses. The first adiabatic inversion pulse inverts the magnetization of long-T2 water and the second one inverts that of fat. Short-T2 species experience a significant transverse relaxation during the long adiabatic inversion process, and are minimally affected by the inversion pulses. Data acquisition with a short TE of 8 μs starts following a time delay of TI1 for the inverted water magnetization to reach a null point, and a time delay of TI2 for the inverted fat magnetization to reach a null point. The suppression of long-T2 species depends on proper combination of TI1, TI2 and TR. It is insensitive to RF inhomogeneities because of the adiabatic inversion pulses. The feasibility of this dual inversion recovery ultrashort TE (DIR UTE) technique was demonstrated on phantoms, cadaveric specimens and healthy volunteers using a clinical 3T scanner. High image contrast was achieved for the deep radial and calcified layers of articular cartilage, cortical bone and the Achilles tendon.