Takeuchi Michihiro, Sekino Masaki, Iriguchi Norio, Ueno Shoogo
Department of Biomedical Engineering, Graduate School of Medicine, University of Tokyo, Japan.
Magn Reson Med Sci. 2004;3(4):153-7. doi: 10.2463/mrms.3.153.
In this study, we investigated the effect of structural differences in collagen fibers in relation to the spin-spin (T2) relaxation time of surrounding water molecules. We propose a simple experimental model of the magic angle effect based on magnetically oriented collagen gels. Experiments were performed with a 4.7T magnetic resonance imaging (MRI) system with a quadrature radio frequency coil operated at 200 MHz for 1H resonance. Collagen gels were polymerized from collagen solutions exposed to a 4.7T magnetic field for 120 min. The T2 relaxation time was measured with the Carr-Purcell-Meiboom-Gill (CPMG) sequence. The apparent diffusion coefficient (ADC) was measured with the stimulated echo acquisition mode (STEAM) sequence with a motion-probing gradient (MPG). Orienting the collagen fibers at an angle of about 55 degrees to the main magnetic field caused an increase in the T2 relaxation times of water molecules in the collagen gels. The ADC in the direction parallel to the fibers was larger than that in the direction perpendicular to the fibers. The increase in the T2 relaxation time and ADC are attributed to a change in the magnetic interaction between the water molecules and collagen fibers.
在本研究中，我们研究了胶原纤维结构差异对周围水分子自旋 - 自旋（T2）弛豫时间的影响。我们基于磁取向胶原凝胶提出了一个简单的魔角效应实验模型。实验使用一台4.7T磁共振成像（MRI）系统进行，该系统配备一个正交射频线圈，以200MHz运行用于氢质子共振。胶原凝胶由暴露于4.7T磁场120分钟的胶原溶液聚合而成。T2弛豫时间用Carr - Purcell - Meiboom - Gill（CPMG）序列测量。表观扩散系数（ADC）用带有运动探测梯度（MPG）的刺激回波采集模式（STEAM）序列测量。使胶原纤维与主磁场成约55度角取向会导致胶原凝胶中水分子的T2弛豫时间增加。纤维平行方向的ADC大于纤维垂直方向的ADC。T2弛豫时间和ADC的增加归因于水分子与胶原纤维之间磁相互作用的变化。
