Zhang Xiaozhong, Webb Andrew
Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
J Magn Reson. 2004 Sep;170(1):149-55. doi: 10.1016/j.jmr.2004.05.004.
A design is presented for a "phased array" of four transmit/receive saddle-geometry volume coils for microimaging at 600 MHz within a 45 mm clear-bore vertical magnet. The small size of the coils, approximately 10 mm in length, and high frequency of operation both present considerable challenges for the design of a phased array. The particular design consists of four saddle coils, stacked vertically, in order to produce an array suitable for imaging samples, typical of many microimaging studies, with a large length:diameter ratio. Optimal coil overlap is used to reduce the mutual inductance between adjacent coils, and capacitive networks are used to maximize the isolation between all of the coils. Standard 50 Omega input impedance preamplifiers are used so that the preamplifiers do not have to be integrated directly into the probe. Isolation between coils was better than 20 dB for all coil pairs. An increase in signal-to-noise of 70 +/- 3% was achieved, averaged over the whole array, compared to a single coil of the same dimensions. High resolution phased array images are shown for ex vivo tissue samples.
本文介绍了一种用于在45毫米内径垂直磁体中进行600兆赫兹微成像的“相控阵”设计，该相控阵由四个发射/接收鞍形几何体积线圈组成。线圈尺寸小，长度约为10毫米，且工作频率高，这对相控阵的设计都提出了相当大的挑战。具体设计包括四个垂直堆叠的鞍形线圈，以产生适合对许多微成像研究中的典型样本进行成像的阵列，这些样本具有较大的长度与直径比。采用最佳的线圈重叠方式来降低相邻线圈之间的互感，并使用电容网络来最大化所有线圈之间的隔离度。使用标准的50欧姆输入阻抗前置放大器，这样前置放大器无需直接集成到探头中。所有线圈对之间的线圈隔离度均优于20分贝。与相同尺寸的单个线圈相比，整个阵列的平均信噪比提高了70±3%。展示了离体组织样本的高分辨率相控阵图像。
