Tay Zhi Wei, Goodwill Patrick W, Hensley Daniel W, Taylor Laura A, Zheng Bo, Conolly Steven M
Department of Bioengineering, 340 Hearst Memorial Mining Building, University of California, Berkeley, Berkeley, CA, USA.
Magnetic Insight, Inc. 980 Atlantic Avenue Suite102 Alameda, CA 9450, USA.
Sci Rep. 2016 Sep 30;6:34180. doi: 10.1038/srep34180.
Magnetic Particle Imaging (MPI) is a promising new tracer modality with zero attenuation deep in tissue, high contrast and sensitivity, and an excellent safety profile. However, the spatial resolution of MPI is limited to around 1 mm currently and urgently needs to be improved for clinical applications such as angiography and brain perfusion. Although MPI resolution is highly dependent on tracer characteristics and the drive waveforms, optimization is limited to a small subset of possible excitation strategies by current MPI hardware that only does sinusoidal drive waveforms at very few frequencies. To enable a more comprehensive and rapid optimization of drive waveforms for multiple metrics like resolution and signal strength simultaneously, we demonstrate the first untuned MPI spectrometer/relaxometer with unprecedented 400 kHz excitation bandwidth and capable of high-throughput acquisition of harmonic spectra (100 different drive-field frequencies in only 500 ms). It is also capable of arbitrary drive-field waveforms which have not been experimentally evaluated in MPI to date. Its high-throughput capability, frequency-agility and tabletop size makes this Arbitrary Waveform Relaxometer/Spectrometer (AWR) a convenient yet powerfully flexible tool for nanoparticle experts seeking to characterize magnetic particles and optimize MPI drive waveforms for in vitro biosensing and in vivo imaging with MPI.
磁粒子成像（MPI）是一种很有前景的新型示踪模态，在组织深部具有零衰减、高对比度和灵敏度，以及出色的安全性。然而，目前MPI的空间分辨率限制在约1毫米左右，对于血管造影和脑灌注等临床应用，迫切需要提高分辨率。尽管MPI分辨率高度依赖于示踪剂特性和驱动波形，但由于当前MPI硬件仅在极少数频率下进行正弦驱动波形，优化仅限于一小部分可能的激发策略。为了能够同时针对分辨率和信号强度等多个指标更全面、快速地优化驱动波形，我们展示了首个无需调谐的MPI光谱仪/弛豫仪，其具有前所未有的400kHz激发带宽，能够在仅500毫秒内高通量采集谐波光谱（100个不同的驱动场频率）。它还能够生成任意驱动场波形，而这在MPI中迄今为止尚未经过实验评估。其高通量能力、频率捷变特性和桌面尺寸，使得这种任意波形弛豫仪/光谱仪（AWR）成为纳米颗粒专家的便捷且极具灵活性的工具，这些专家旨在表征磁性颗粒，并为体外生物传感和MPI体内成像优化MPI驱动波形。
