Ruck Laurent, Egger Nico, Wilferth Tobias, Schirmer Judith, Gast Lena Vanessa, Nagelstraßer Sophia, Wildenberg Saskia, Bitz Andreas, Lanz Titus, Platt Tanja, Konstandin Simon, Kopp Christoph, Uder Michael, Nagel Armin Michael
Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
Electrical Engineering and Information Technology, University of Applied Sciences - FH Aachen, Aachen, Germany.
Magn Reson Med. 2025 Jul;94(1):231-241. doi: 10.1002/mrm.30426. Epub 2025 Mar 10.
To evaluate the feasibility of interleaved Na/H cardiac MRI at 7 T using H parallel transmission (pTx) pulses.
A combined setup consisting of a Na volume coil and two H transceiver arrays was employed and the transmit and receive characteristics were compared in vitro with those of the uncombined radiofrequency coils. Furthermore, the implemented interleaved Na/H pTx sequence was validated in phantom measurements and applied to four healthy subjects. For the latter, three customized H excitation pulses (universal and individual phase shims (UPS/IPS) and individual 4kT pulses (4kT)) were employed in the interleaved Na/H pTx sequence and compared with the vendor-provided default cardiac phase shim (DPS).
Combining both coils resulted in a reduction of the mean Na transmit field (B ) efficiency and Na signal-to-noise ratio by 18.9% and 15.4% for the combined setup, whereas the H B efficiency was less influenced (-4.7%). Compared with single-nuclear acquisitions, interleaved dual-nuclear Na/H MRI showed negligible influence on Na and H image quality. For all three customized H pTx pulses the B homogeneity was improved (coefficients of variation: CV = 0.30, CV = 0.23, CV = 0.15) and no H signal dropouts occurred compared with the vendor-provided default phase shim (CV = 0.37).
The incorporation of customized H pTx pulses in an interleaved Na/H sequence scheme was successfully demonstrated at 7 T and improvements of the H B homogeneity within the heart were shown. Combining interleaved Na/H MRI with H pTx is an important tool to enable robust quantification of myocardial tissue sodium concentrations at 7 T within clinically acceptable acquisition times.
评估在7T场强下使用氢并行发射（pTx）脉冲进行交错钠/氢心脏磁共振成像（MRI）的可行性。
采用由一个钠容积线圈和两个氢收发阵列组成的联合装置，并在体外将其发射和接收特性与未组合的射频线圈进行比较。此外，在体模测量中验证了所实施的交错钠/氢pTx序列，并将其应用于四名健康受试者。对于后者，在交错钠/氢pTx序列中采用了三个定制的氢激发脉冲（通用和个体相位垫片（UPS/IPS）以及个体4kT脉冲（4kT）），并与供应商提供的默认心脏相位垫片（DPS）进行比较。
组合两个线圈导致联合装置的平均钠发射场（B）效率和钠信噪比分别降低了18.9%和15.4%，而氢B效率受影响较小（-4.7%）。与单核采集相比，交错双核钠/氢MRI对钠和氢图像质量的影响可忽略不计。对于所有三个定制的氢pTx脉冲，B均匀性均得到改善（变异系数：CV = 0.30，CV = 0.23，CV = 0.15），与供应商提供的默认相位垫片（CV = 0.37）相比，未出现氢信号丢失。
在7T场强下成功证明了在交错钠/氢序列方案中纳入定制的氢pTx脉冲，并显示出心脏内氢B均匀性得到改善。将交错钠/氢MRI与氢pTx相结合是在临床可接受的采集时间内对7T场强下心肌组织钠浓度进行可靠定量的重要工具。
