Reduction of residual dipolar interaction in cartilage by spin-lock technique
Reduction of residual dipolar interaction in cartilage by spin-lock technique
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DOI：
10.1002/mrm.20241
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发表时间：
2004-11-01
影响因子：
3.3
通讯作者：
Reddy, R
中科院分区：
文献类型：
--
作者：
Akella, SVS;Regatte, RR;Reddy, R
研究了射频自旋锁脉冲对关节软骨薄层MR图像的影响。在4.7特斯拉小口径MRI扫描仪上对牛软骨塞进行自旋锁定MRI实验，并在1.5特斯拉临床扫描仪上对体内人膝关节软骨进行自旋锁定MRI实验。当软骨表面法线与B 0平行时，软骨栓在T2加权像上表现为典型的层状结构，而在T1 p加权像上则无层状结构。在“魔角”方向（软骨表面法线与B 0成54.7 °），T-2和T-1 p图像均未显示板层。同时，在整个软骨的两个方向上，T-1 p值均大于T-2。T-1 p色散（即，观察到弛豫速率对自旋锁定频率ω（1）的依赖性，其在平行和魔角取向上都达到接近2kHz的稳态值。这些结果表明，残余偶极相互作用，从运动限制水和松弛过程，如化学交换，有助于T-1 p分散在软骨。此外，可以通过施加自旋锁定RF脉冲来减少人类关节软骨中的层状外观，这可以导致软骨中的退行性变化的更准确的诊断。Magn Reson Med 52：1103-1109，2004年。(C)2004 Wiley-Liss，Inc.
The influence of radiofrequency (RF) spin-lock pulse on the laminar appearance of articular cartilage in MR images was investigated. Spin-lock MRI experiments were performed on bovine cartilage plugs on a 4.7 Tesla small-bore MRI scanner, and on human knee cartilage in vivo on a 1.5 Tesla clinical scanner. When the normal to the surface of cartilage was parallel to B-0, a typical laminar appearence was exhibited in T-2-weighted images of cartilage plugs, but was absent in T-1p-weighted images of the same plugs. At the "magic angle" orientation (when the normal to the surface of cartilage was 54.7degrees with respect to B0), neither the T-2 nor the T-1p images demonstrated laminae. At the same time, T-1p values were greater than T-2 at both orientations throughout the cartilage. T-1p dispersion (i.e., the dependence of the relaxation rate on the spin-lock frequency omega(1)) was observed, which reached a steady-state value of close to 2 kHz in both parallel and magic-angle orientations. These results suggest that residual dipolar interaction from motionally-restricted water and relaxation processes, such as chemical exchange, contribute to T-1p dispersion in cartilage. Further, one can reduce the laminar appearance in human articular cartilage by applying spin-lock RF pulses, which may lead to a more accurate diagnosis of degenerative changes in cartilage. Magn Reson Med 52:1103-1109, 2004. (C) 2004 Wiley-Liss, Inc.