Magnetic Resonance Imaging Assisted by Wireless Passive Implantable Fiducial e-Markers
Magnetic Resonance Imaging Assisted by Wireless Passive Implantable Fiducial e-Markers
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DOI：
10.1109/access.2017.2752649
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发表时间：
2017-01-01
期刊：
影响因子：
3.9
通讯作者：
Demir, Hilmi Volkan
中科院分区：
文献类型：
--
作者：
Gokyar, Sayim;Alipour, Akbar;Demir, Hilmi Volkan
本文报告了一种无线无源谐振器架构，该架构用作磁共振成像（MRI）中用于内部标记目的的基准电子标记（e-marker）。作为概念验证演示，一类双层，亚厘米螺旋谐振器的微制造和调谐到123 MHz的工作频率为三T MRI系统。研究了各种几何参数对电子标记物共振频率的影响，并使用全波微波解算器分析了由此产生的比吸收率（SAR）增加。计算了BiF场分布，并与实验结果进行了比较。作为定位硬膜下电极的示例性应用，这些标记与硬膜下电极配对。结果表明，这种具有生物相容性成分的亚厘米级自谐振电子标记物可在MRI中设计并用于植入物标记，定位精度为亚毫米级。在该应用中，所提出的谐振器架构实现了约50的自由空间品质因数（Q因数）。然而，这种结构在某些情况下导致SAR增加，这限制了其在体内成像实践中的使用。研究结果表明，这些植入式谐振器在MRI中作为多模态成像的替代品，对无线基准电子标记具有很大的希望。
This paper reports a wireless passive resonator architecture that is used as a fiducial electronic marker (e-marker) intended for internal marking purposes in magnetic resonance imaging (MRI). As a proof of-concept demonstration, a class of double-layer, sub-cm helical resonators were microfabricated and tuned to the operating frequency of 123 MHz for a three T MRI system. Effects of various geometrical parameters on the resonance frequency of the e-marker were studied, and the resulting specific absorption rate (SAR) increase was analyzed using a full-wave microwave solver. The BiF field distribution was calculated, and experimental results were compared. As an exemplary application to locate subdural electrodes, these markers were paired with subdural electrodes. It was shown that such sub-cm self-resonant e-markers with biocompatible constituents can be designed and used for implant marking, with sub-mm positioning accuracy, in MRI. In this application, a free-space quality factor (Q-factor) of approximately 50 was achieved for the proposed resonator architecture. However, this structure caused an SAR increase in certain cases, which limits its usage for in vivo imaging practices. The findings indicate that these implantable resonators hold great promise for wireless fiducial e-marking in MRI as an alternative to multimodal imaging.