CIBM Center for Biomedical Imaging, Lausanne, Switzerland.
Animal Imaging and Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland.
Magn Reson Med. 2025 Feb;93(2):481-489. doi: 10.1002/mrm.30321. Epub 2024 Oct 4.
Phosphorus MRS (P MRS) enables noninvasive assessment of energy metabolism, yet its application is hindered by sensitivity limitations. To overcome this, often high magnetic fields are used, leading to challenges such as spatial inhomogeneity and therefore the need for accurate flip-angle determination in accelerated acquisitions with short TRs. In response to these challenges, we propose a novel short TR and look-up table-based double-angle method for fast 3D P mapping (fDAM).
Our method incorporates 3D weighted stack-of-spiral gradient-echo acquisitions and a frequency-selective pulse to enable efficient mapping based on the phosphocreatine signal at 7 T. Protocols were optimized using simulations and validated through phantom experiments. The method was validated in the human brain using a P 1Ch-trasmit/32Ch-receive coil and skeletal muscle using a birdcage H/P volume coil.
The results of fDAM were compared with the classical DAM. A good correlation (r = 0.95) was obtained between the two maps. A 3D P mapping in the human calf muscle was achieved in about 10:50 min using a birdcage volume coil, with a 20% extended coverage (number of voxels with SNR > 3) relative to that of the classical DAM (24 min). fDAM also enabled the first full-brain coverage P 3D mapping in approximately 10:15 min using a 1Ch-transmit/32Ch-receive coil.
fDAM is an efficient method for P 3D mapping, showing promise for future applications in rapid P MRSI.
磷磁共振波谱（P MRS）能够实现非侵入性的能量代谢评估，但由于灵敏度限制，其应用受到阻碍。为了克服这一问题，通常需要使用高磁场，这导致了空间不均匀性等问题，因此需要在短 TR 的加速采集时准确确定翻转角。针对这些挑战，我们提出了一种新的基于短 TR 和查找表的双角方法，用于快速 3D P 映射（fDAM）。
我们的方法结合了 3D 加权螺旋梯度回波采集和频率选择脉冲，以便在 7T 下基于磷酸肌酸信号进行高效的映射。使用模拟和体模实验对协议进行了优化。该方法在人体大脑中使用 P 1Ch 发射/32Ch 接收线圈进行了验证，并在骨骼肌中使用鸟笼 H/P 容积线圈进行了验证。
fDAM 的结果与经典 DAM 进行了比较。两种图谱之间得到了很好的相关性（r=0.95）。使用鸟笼容积线圈在人体小腿肌肉中实现了约 3D P 映射，与经典 DAM 相比，扩展覆盖范围（信噪比>3 的体素数量）增加了 20%（24 分钟）。fDAM 还使用 1Ch 发射/32Ch 接收线圈实现了大约 10:15 分钟的全脑覆盖 P 3D 映射。
fDAM 是一种高效的 P 3D 映射方法，有望在快速 P MRSI 中得到广泛应用。
