Arnal B, Wei C-W, Li J, Gao X, O'Donnell M
University of Washington, Dept. of Bioengineering, Seattle, WA, USA.
J Opt. 2016 Feb;18(2). doi: 10.1088/2040-8978/18/2/024009. Epub 2016 Jan 19.
Highly specific molecular imaging with photoacoustics (PA) must suppress background endogenous signals while maintaining signals from target nanoagents. Magneto-motive PA was introduced to perform motion-based background suppression using a low frequency magnetic field. Previous studies show suppression based on displacement magnitude can suffer if significant physiological motion is present. This limitation can be overcome using cyclic magneto-motive PA (cmmPA), where multiple cycles of an ac magnetic field are used and the coherence of detected displacements is the retrieved information. In this paper, we show a method to enhance the magnetic response of an electromagnet specifically for cmmPA. Several magnetic frequencies were tested and a simple model is proposed to describe displacement frequency dependence. By choosing optimal parameters based on this model, we show that the technique can detect a low number of tagged cells using either US-based or PA-based displacement estimation. In addition, robustness to physiological motion is demonstrated in a moving phantom.
利用光声（PA）进行的高特异性分子成像必须抑制背景内源信号，同时保持来自目标纳米剂的信号。引入了磁动力光声技术，以利用低频磁场进行基于运动的背景抑制。先前的研究表明，如果存在显著的生理运动，基于位移幅度的抑制可能会受到影响。使用循环磁动力光声（cmmPA）可以克服这一限制，其中使用交流磁场的多个周期，并且检测到的位移的相干性是检索到的信息。在本文中，我们展示了一种专门用于cmmPA的增强电磁铁磁响应的方法。测试了几种磁频率，并提出了一个简单的模型来描述位移频率依赖性。通过基于该模型选择最佳参数，我们表明该技术可以使用基于超声或基于光声的位移估计来检测少量标记细胞。此外，在移动模型中证明了对生理运动的鲁棒性。
