Larson Peder E Z, Gurney Paul T, Nayak Krishna, Gold Garry E, Pauly John M, Nishimura Dwight G
Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305-9510, USA.
Magn Reson Med. 2006 Jul;56(1):94-103. doi: 10.1002/mrm.20926.
Ultrashort echo time (UTE) imaging has shown promise as a technique for imaging tissues with T2 values of a few milliseconds or less. These tissues, such as tendons, menisci, and cortical bone, are normally invisible in conventional magnetic resonance imaging techniques but have signal in UTE imaging. They are difficult to visualize because they are often obscured by tissues with longer T2 values. In this article, new long-T2 suppression RF pulses that improve the contrast of short-T2 species are introduced. These pulses are improvements over previous long-T2 suppression pulses that suffered from poor off-resonance characteristics or T1 sensitivity. Short-T2 tissue contrast can also be improved by suppressing fat in some applications. Dual-band long-T2 suppression pulses that additionally suppress fat are also introduced. Simulations, along with phantom and in vivo experiments using 2D and 3D UTE imaging, demonstrate the feasibility, improved contrast, and improved sensitivity of these new long-T2 suppression pulses. The resulting images show predominantly short-T2 species, while most long-T2 species are suppressed.
超短回波时间（UTE）成像已展现出作为一种对T2值为几毫秒或更短的组织进行成像的技术的前景。这些组织，如肌腱、半月板和皮质骨，在传统磁共振成像技术中通常不可见，但在UTE成像中有信号。它们难以可视化，因为它们常常被具有较长T2值的组织所掩盖。在本文中，引入了新的长T2抑制射频脉冲，这些脉冲可改善短T2物质的对比度。这些脉冲是对先前长T2抑制脉冲的改进，先前的脉冲存在失谐特性不佳或T1敏感性问题。在某些应用中，通过抑制脂肪也可以改善短T2组织对比度。还引入了额外抑制脂肪的双波段长T2抑制脉冲。使用二维和三维UTE成像进行的模拟以及体模和体内实验证明了这些新的长T2抑制脉冲的可行性、改善的对比度和提高的敏感性。所得图像主要显示短T2物质，而大多数长T2物质被抑制。
