Kneeland J B, Carrera G F, Middleton W D, Campagna N F, Ryan L M, Jesmanowicz A, Froncisz W, Hyde J S
Radiology. 1986 Sep;160(3):695-9. doi: 10.1148/radiology.160.3.3737908.
A new class of radio frequency (RF) coils for magnetic resonance (MR) imaging and spectroscopy is introduced. The coils consist of two loop-gap resonators of equal diameters positioned along a common axis. They are tuned to the mode in which the current in the two loops flows in opposite directions. These coils are "decoupled" from a uniform excitation field of arbitrary orientation (including circularly polarized fields) by intrinsic decoupling and by means of back-to-back fast recovery diodes. Measurements made with the coils and a phantom saline tank indicate that the signal-to-noise ratio obtainable with these coils is almost identical to that obtained with single loops. Imaging of several anatomic areas, including knee, wrist, and shoulder, has been performed with a 1.5-T MR system that uses circularly polarized RF. A small series of patients with torn rotator cuffs underwent imaging. Difficulties in establishing the diagnosis with MR imaging because of anatomic complexity are illustrated. The value of pulse sequences with long repetition times to increase the signal intensity of fluid in the joint is shown.
介绍了一种用于磁共振（MR）成像和光谱学的新型射频（RF）线圈。这些线圈由两个直径相等的环形缝隙谐振器组成，它们沿公共轴排列。它们被调谐到两个环路中的电流沿相反方向流动的模式。通过固有去耦和背对背快速恢复二极管，这些线圈与任意取向的均匀激励场（包括圆极化场）“去耦”。用这些线圈和体模盐水槽进行的测量表明，使用这些线圈可获得的信噪比几乎与单环获得的信噪比相同。使用圆极化射频的1.5-T MR系统对包括膝盖、手腕和肩膀在内的几个解剖区域进行了成像。对一小部分肩袖撕裂患者进行了成像。说明了由于解剖结构复杂而在通过MR成像进行诊断时遇到的困难。显示了使用长重复时间的脉冲序列来增加关节内液体信号强度的价值。
