Vullo T, Pascone R, Mancuso R, Zipagan R, Cahill P T
New York Hospital-Cornell University Medical College, Department of Radiology, New York City 10021.
Magn Reson Imaging. 1994;12(5):785-97. doi: 10.1016/0730-725x(94)92203-9.
Transmission line theory, validated for the standard cylindrical birdcage coil, has been employed for the analysis of a rectangular birdcage resonator which is useful for MR imaging of the hand. Due to lack of cylindrical symmetry in the rectangular coil, RF field uniformity was evaluated and found to be critically dependent upon the choice of column from which the coil was linearly driven. Effective L1 and L2 inductance elements were determined using known formulas for self and mutual inductance contributions, and compensation of the different inductance elements of the hand coil was performed to produce cylindrically symmetric birdcage current patterns. RF field mapping using the Biot-Savart law demonstrated a rectangular coil sensitivity 22% greater than a comparable cylindrical version. MR hand and wrist images were acquired using the rectangular birdcage coil. In addition, transmission line analysis was extended to other noncylindrical birdcage geometries.
传输线理论已被用于分析一种用于手部磁共振成像的矩形鸟笼式谐振器，该理论已针对标准圆柱形鸟笼式线圈得到验证。由于矩形线圈缺乏圆柱对称性，因此对射频场均匀性进行了评估，发现其严重依赖于线圈线性驱动所采用的列的选择。使用已知的自感和互感贡献公式确定了有效的L1和L2电感元件，并对手部线圈的不同电感元件进行了补偿，以产生圆柱对称的鸟笼式电流模式。利用毕奥-萨伐尔定律进行的射频场映射表明，矩形线圈的灵敏度比类似的圆柱形线圈高22%。使用矩形鸟笼式线圈采集了手部和腕部的磁共振图像。此外，传输线分析已扩展到其他非圆柱形鸟笼式几何结构。
