Center for Biomedical Imaging, Department of Radiology, New York University Langone Medical Center, New York, NY 10016, USA.
NMR Biomed. 2010 Feb;23(2):142-51. doi: 10.1002/nbm.1435.
The quality of an RF detector coil design is commonly judged on how it compares with other coil configurations. The aim of this article is to develop a tool for evaluating the absolute performance of RF coil arrays. An algorithm to calculate the ultimate intrinsic signal-to-noise ratio (SNR) was implemented for a spherical geometry. The same imaging tasks modeled in the calculations were reproduced experimentally using a 32-element head array. Coil performance maps were then generated based on the ratio of experimentally measured SNR to the ultimate intrinsic SNR, for different acceleration factors associated with different degrees of parallel imaging. The relative performance in all cases was highest near the center of the samples (where the absolute SNR was lowest). The highest performance was found in the unaccelerated case and a maximum of 85% was observed with a phantom whose electrical properties are consistent with values in the human brain. The performance remained almost constant for 2-fold acceleration, but deteriorated at higher acceleration factors, suggesting that larger arrays are needed for effective highly-accelerated parallel imaging. The method proposed here can serve as a tool for the evaluation of coil designs, as well as a tool to guide the development of original designs which may begin to approach the optimal performance.
RF 探测器线圈设计的质量通常通过与其他线圈配置的比较来判断。本文的目的是开发一种用于评估 RF 线圈阵列绝对性能的工具。已经为球形几何结构实现了用于计算最终固有信噪比 (SNR) 的算法。使用 32 个元素的头部阵列通过实验再现了相同的成像任务。然后，基于实验测量的 SNR 与最终固有 SNR 的比值，针对与不同程度的并行成像相关联的不同加速因子，生成了线圈性能图。在所有情况下，相对性能在样品的中心附近最高（那里的绝对 SNR 最低）。在未加速的情况下，性能最高，对于电特性与人类大脑中的值一致的体模，观察到的最高性能为 85%。在 2 倍加速的情况下，性能几乎保持不变，但在更高的加速因子下会恶化，这表明需要更大的阵列来实现有效的高加速并行成像。这里提出的方法可以用作评估线圈设计的工具，以及指导可能开始接近最佳性能的原始设计开发的工具。
