Ma Ya-Jun, Carl Michael, Shao Hongda, Tadros Anthony S, Chang Eric Y, Du Jiang
Department of Radiology, University of California, San Diego, CA, USA.
GE Healthcare, San Diego, CA, USA.
NMR Biomed. 2017 Jun;30(6). doi: 10.1002/nbm.3709. Epub 2017 Mar 20.
We report a novel three-dimensional (3D) ultrashort echo time (UTE) sequence employing Cones trajectory and T preparation (UTE-Cones-T ) for quantitative T assessment of short T tissues in the musculoskeletal system. A basic 3D UTE-Cones sequence was combined with a spin-locking preparation pulse for T contrast. A relatively short TR was used to decrease the scan time, which required T measurement and compensation using 3D UTE-Cones data acquisitions with variable TRs. Another strategy to reduce the total scan time was to acquire multiple Cones spokes (N ) after each T preparation and fat saturation. Four spin-locking times (TSL = 0-20 ms) were acquired over 12 min, plus another 7 min for T measurement. The 3D UTE-Cones-T sequence was compared with a two-dimensional (2D) spiral-T sequence for the imaging of a spherical CuSO phantom and ex vivo meniscus and tendon specimens, as well as the knee and ankle joints of healthy volunteers, using a clinical 3-T scanner. The CuSO phantom showed a T value of 76.5 ± 1.6 ms with the 2D spiral-T sequence, as well as 85.7 ± 3.6 and 89.2 ± 1.4 ms for the 3D UTE-Cones-T sequences with N of 1 and 5, respectively. The 3D UTE-Cones-T sequence provided shorter T values for the bovine meniscus sample relative to the 2D spiral-T sequence (10-12 ms versus 16 ms, respectively). The cadaveric human Achilles tendon sample could only be imaged with the 3D UTE-Cones-T sequence (T = 4.0 ± 0.9 ms), with the 2D spiral-T sequence demonstrating near-zero signal intensity. Human studies yielded T values of 36.1 ± 2.9, 18.3 ± 3.9 and 3.1 ± 0.4 ms for articular cartilage, meniscus and the Achilles tendon, respectively. The 3D UTE-Cones-T sequence allows volumetric T measurement of short T tissues in vivo.
我们报告了一种新颖的三维（3D）超短回波时间（UTE）序列，该序列采用圆锥轨迹和T准备（UTE-Cones-T）来对肌肉骨骼系统中的短T2组织进行定量T2评估。一个基本的3D UTE-Cones序列与一个用于T2对比的自旋锁定准备脉冲相结合。使用了相对较短的重复时间（TR）来减少扫描时间，这需要使用具有可变TR的3D UTE-Cones数据采集进行T2测量和补偿。另一种减少总扫描时间的策略是在每次T2准备和脂肪饱和后采集多个圆锥辐条（N）。在12分钟内采集了四个自旋锁定时间（TSL = 0 - 20毫秒），另外还需要7分钟进行T2测量。使用临床3-T扫描仪，将3D UTE-Cones-T序列与二维（2D）螺旋-T2序列用于球形硫酸铜体模、离体半月板和肌腱标本以及健康志愿者的膝关节和踝关节成像进行比较。对于2D螺旋-T2序列，硫酸铜体模的T2值为76.5±1.6毫秒，对于N为1和5的3D UTE-Cones-T序列，分别为85.7±3.6毫秒和89.2±1.4毫秒。相对于2D螺旋-T2序列，3D UTE-Cones-T序列为牛半月板样本提供了更短的T2值（分别为10 - 12毫秒和16毫秒）。尸体人跟腱样本只能用3D UTE-Cones-T序列成像（T2 = 4.0±0.9毫秒），2D螺旋-T2序列显示信号强度接近零。人体研究中，关节软骨、半月板和跟腱的T2值分别为36.1±2.9毫秒、18.3±3.9毫秒和3.1±0.4毫秒。3D UTE-Cones-T序列允许在体内对短T2组织进行容积T2测量。
