DESIGN OF DEDICATED SHIM COILS

简介：软骨的弥散加权成像可以提供 深入了解正常软骨结构，软骨缺损， 移植 具体来说，弥散加权图像可以证明 胶原纤维的结构取向。 我们已经开发出一种 用于对关节软骨中的扩散效应进行成像的方法。 材料和方法：采用弥散加权成像序列， 软骨使用传统的Stejskal-Tanner扩散梯度， 圆形回波平面读出轨迹和螺旋导航脉冲 以减少运动效应。 由于软骨的T2弛豫时间 短，回波时间保持在最小值（51 ms），同时仍允许 扩散加权。 面内空间分辨率为1.3 x 1.4 mm。可在约5分钟内采集9个切片。 b值 分别为0、393和486 s/mm^2。 所有成像均在1.5T GE Signa上完成 使用超声速梯度。 结果：10名正常志愿者和1名 一位接受软骨移植的病人已经被研究过了。 正常 关节软骨显示表观扩散系数（ADC） 范围为1到2 × 10 ^-3 mm^2/s，与文献中的结果相当 在软骨/骨栓样本上获得的结果。 adc值 软骨/骨界面的正常软骨增加 连接表面。 结论：体内弥散加权成像 关节软骨的移植可以在传统的全身 扫描仪 这种类型的成像可能会产生关于 存在的胶原纤维的方向和类型。 有可能 为了跟踪软骨细胞移植的发展和整合， 并区分纤维软骨和透明软骨， 移植部位

Introduction: Diffusion-weighted imaging of cartilage may provide insight into normal cartilage structure, cartilage defects, and transplants. Specifically, diffusion-weighted images may demonstrate structural orientation of the collagen fibers. We have developed a method for imaging diffusion effects in articular cartilage. Materials and Methods: The diffusion-weighted imaging sequence for cartilage uses conventional Stejskal-Tanner diffusion gradients, a circular echo-planar readout trajectory, and a spiral navigator pulse to reduce motion effects. Since the T2 relaxation time of cartilage is short, echo time is kept to a minimum (51 ms) while still allowing diffusion weighting to be applied. In-plane spatial resolution is 1.3 x 1.4 mm. Nine slices can be acquired in about 5 minutes. B-values were 0, 393, and 486 s/mm^2. All imaging was done on a 1.5T GE Signa with Echospeed gradients. Results: Ten normal volunteers and one patient with a cartilage transplant have been studied. Normal articular cartilage shows an apparent diffusion coefficient (ADC) ranging from 1 to 2x10^-3 mm^2/s, which compares well with literature results obtained on cartilage/bone plug specimens. ADC values increase in normal cartilage going from the cartilage/bone interface to the joint surface. Conclusion: In-vivo diffusion-weighted imaging of articular cartilage can be performed on a conventional whole-body scanner. This type of imaging may yield new information about the orientation and type of collagen fibers present. It may be possible to follow the development and integration of chondrocyte transplants, and to distinguish fibrocartilage from hyaline cartilage at the transplant site.