Kruse Marlen, Nordenström Simon, Hartwig Stefan, Marquetand Justus, Lebedev Victor, Middelmann Thomas, Broser Philip J
Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587 Berlin, Germany.
Department of Neural Dynamics and Magnetoencephalography, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Str. 27 Tübingen, Germany.
Biomed Phys Eng Express. 2025 Feb 6;11(2). doi: 10.1088/2057-1976/adaec5.
Mapping the myomagnetic field of a straight and easily accessible muscle after electrical stimulation using triaxial optically pumped magnetometers (OPMs) to assess potential benefits for magnetomyography (MMG).Six triaxial OPMs were arranged in two rows with three sensors each along the abductor digiti minimi (ADM) muscle. The upper row of sensors was inclined by 45° with respect to the lower row and all sensors were aligned closely to the skin surface without direct contact. Then, the electromagnetic muscle activity was electrically evoked utilizing stepwise increasing currents at the cubital tunnel at the ulnar nerve. Evoked myomagnetic activity was recorded with 18 channels, three per sensor. As the measurements were performed in PTB's magnetically shielded room (BMSR-2) no averaging and only moderate filtering was applied.The myomagnetic vector field could be successfully mapped. The obtained spatial structure with a radial symmetry corresponds to the expectations from the ADM's parallel muscle architecture. The temporal evolution exhibits an up to four-phasic shape. Implications for future experiments are derived and needs for sensor performance improvements are identifiedThe use of an OPM array with small (∼3 mm edge length) sensing voxels enabled the mapping of the magnetic vector field of the ADM. This allowed visualization of the spatiotemporal evolution of the muscle's evoked magnetic field and gives implications for future experiments. In the future, high density OPM grids may enable high-accuracy determination of muscle parameters such as innervation zone position, pennation angle, and propagation velocities.
使用三轴光泵磁力仪（OPM）在电刺激后绘制一块笔直且易于触及的肌肉的肌磁场，以评估磁肌电图（MMG）的潜在益处。六个三轴OPM沿小指展肌（ADM）肌肉排成两排，每排三个传感器。上排传感器相对于下排倾斜45°，所有传感器都紧密对准皮肤表面但不直接接触。然后，通过在尺神经肘管处逐步增加电流来电诱发电磁肌肉活动。用18个通道记录诱发的肌磁活动，每个传感器三个通道。由于测量是在PTB的磁屏蔽室（BMSR - 2）中进行的，因此未进行平均处理，仅应用了适度滤波。肌磁矢量场能够成功绘制。所获得的具有径向对称性的空间结构与ADM平行肌肉结构的预期相符。时间演变呈现出多达四相的形状。得出了对未来实验的启示，并确定了传感器性能改进的需求。使用具有小（~3毫米边长）传感体素的OPM阵列能够绘制ADM的磁矢量场。这使得能够可视化肌肉诱发磁场的时空演变，并为未来实验提供了启示。未来，高密度OPM网格可能能够高精度确定肌肉参数，如神经支配区位置、羽状角和传播速度。
