3D imaging with a single-sided sensor:: an open tomograph
3D imaging with a single-sided sensor:: an open tomograph
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DOI：
10.1016/j.jmr.2003.10.018
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发表时间：
2004-02-01
影响因子：
2.2
通讯作者：
Blümich, B
中科院分区：
文献类型：
--
作者：
Perlo, J;Casanova, F;Blümich, B
描述了一种用于对大物体的表面附近的体积区域进行成像的开放式断层摄影机。在获得这样的断层摄影工作的中心成就是一个快速的二维纯相位编码成像方法的设计，以产生一个横截面图像的存在下，高度不均匀的领域。该方法利用Carr-Purcell-Meiboom-Gill（CPMG）样序列中的多回波采集，以显著减少获得2D图像的实验时间或在单个成像实验中空间分辨敏感体积的弛豫时间。与单回波成像技术所需的时间相比，根据T，成像时间可以减少多达两个数量级的因子。完整的回波链衰减也已被用来产生T-2对比度的图像和空间解析的T-2分布的不均匀的对象，显示的结构特性的变化，如橡胶样品的交联密度可以区分这种方法。该序列已在单侧传感器上实现，该传感器配备有优化的磁体几何形状和合适的梯度线圈系统，该梯度线圈系统提供两个垂直的脉冲梯度场。静态磁场定义了平行于扫描仪表面的恒定频率的平面，可以通过重新调整探头频率来选择该平面，以实现对对象的切片选择。将开放式磁体的静态梯度存在下获得的切片选择与两个垂直的脉冲梯度场相结合，获得3D空间分辨率。(C)2003年爱思唯尔公司All rights reserved.
An open tomograph to image volume regions near the surface of large objects is described. The central achievement in getting such a tomograph to work is the design of a fast two-dimensional pure phase encoding imaging method to produce a cross-sectional image in the presence of highly inhomogeneous fields. The method takes advantage of the multi-echo acquisition in a Carr-Purcell-Meiboom-Gill (CPMG)-like sequence to significantly reduce the experimental time to obtain a 2D image or to spatially resolve relaxation times across the sensitive volume in a single imaging experiment. Depending on T, the imaging time can be reduced by a factor of up to two orders of magnitude compared to the one needed by the single-echo imaging technique. The complete echo train decay has been also used to produce T-2 contrast in the images and to spatially resolve the T-2 distribution of an inhomogeneous object, showing that variations of structural properties like the cross-link density of rubber samples can be distinguished by this method. The sequence has been implemented on a single-sided sensor equipped with an optimized magnet geometry and a suitable gradient coil system that provides two perpendicular pulsed gradient fields. The static magnetic field defines flat planes of constant frequency parallel to the surface of the scanner that can be selected by retuning the probe frequency to achieve slice selection into the object. Combining the slice selection obtained under the presence of the static gradient of the open magnet with the two perpendicular pulsed gradient fields, 3D spatial resolution is obtained. (C) 2003 Elsevier Inc. All rights reserved.