Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
Magn Reson Med. 2010 Dec;64(6):1625-39. doi: 10.1002/mrm.22552. Epub 2010 Aug 25.
Three different coil configurations were evaluated through simulation and experimentally to determine safe operating limits and evaluate subject size-dependent performance for prostate imaging at 7 T. The coils included a transceiver endorectal coil (trERC), a 16-channel transceiver external surface array (trESA) and a trESA combined with a receive-only ERC (trESA+roERC). Although the transmit B(1) (B 1+) homogeneity was far superior for the trESA, the maximum achievable B 1+ is subject size dependent and limited by transmit chain losses and amplifier performance. For the trERC, limitations in transmit homogeneity greatly compromised image quality and limited coverage of the prostate. Despite these challenges, the high peak B 1+ close to the trERC and subject size-independent performance provides potential advantages especially for spectroscopic localization where high-bandwidth radiofrequency pulses are required. On the receive side, the combined trESA+roERC provided the highest signal-to-noise ratio and improved homogeneity over the trERC resulting in better visualization of the prostate and surrounding anatomy. In addition, the parallel imaging performance of the trESA+roERC holds strong promise for diffusion-weighted imaging and dynamic contrast-enhanced MRI.
通过模拟和实验评估了三种不同的线圈配置，以确定安全操作极限，并评估在 7T 下进行前列腺成像时与受试者大小相关的性能。这些线圈包括一个收发式直肠内线圈（trERC）、一个 16 通道收发式外表面阵列（trESA）以及一个与仅接收式 ERC 组合的 trESA（trESA+roERC）。尽管 trESA 的发射 B1（B1+）均匀性要远优于其他两种线圈，但最大可实现的 B1+取决于发射链损耗和放大器性能，且与受试者大小有关。对于 trERC，发射均匀性的限制极大地影响了图像质量，并限制了前列腺的覆盖范围。尽管存在这些挑战，但 trERC 附近的高峰值 B1+和与受试者大小无关的性能提供了潜在的优势，特别是在需要高带宽射频脉冲的波谱定位中。在接收端，组合式 trESA+roERC 提供了比 trERC 更高的信噪比和更好的均匀性，从而可以更好地可视化前列腺和周围解剖结构。此外，trESA+roERC 的并行成像性能为扩散加权成像和动态对比增强 MRI 提供了很大的潜力。
