Department of Electrical and Electronics Engineering, National Magnetic Resonance Research Center (UMRAM) National Nanotechnology Research Center and Institute of Material Science and Nanotechnology (UNAM) Department of Physics, Bilkent University, Bilkent, Ankara, Turkey.
Department of Radiology, Ankara Ataturk Training and Research Hospital, Ankara, Turkey.
Magn Reson Med. 2018 Jul;80(1):361-370. doi: 10.1002/mrm.26996. Epub 2017 Nov 16.
The purpose of this study is to develop a wireless, flexible, ultra-thin, and passive radiofrequency-based MRI resonant fiducial marker, and to validate its feasibility in a phantom model and several body regions.
Standard microfabrication processing was used to fabricate the resonant marker. The proposed marker consists of two metal traces in the shape of a square with an edge length of 8 mm, with upper and lower traces connected to each other by a metalized via. A 3T MRI fiducial marking procedure was tested in phantom and ex vivo, and then the marker's performance was evaluated in an MRI experiment using humans. The radiofrequency safety was also tested using temperature sensors in the proximity of the resonator.
A flexible resonator with a thickness of 115 μm and a dimension of 8 × 8 mm was obtained. The experimental results in the phantom show that at low background flip angles (6-18°), the resonant marker enables precise and rapid visibility, with high marker-to-background contrast and signal-to-noise ratio improvement of greater than 10 in the vicinity of the marker. Temperature analysis showed a specific absorption ratio gain of 1.3. Clinical studies further showed a successful biopsy procedure using the fiducial marking functionality of our device.
The ultra-thin and flexible structure of this wireless flexible radiofrequency resonant marker offers effective and safe MR visualization with high feasibility for anatomic marking and guiding at various regions of the body. Magn Reson Med 80:361-370, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
本研究旨在开发一种无线、灵活、超薄且无源的基于射频的 MRI 共振基准标记物，并验证其在体模和多个身体部位中的可行性。
采用标准微加工工艺制作共振标记物。所提出的标记物由两个边长为 8mm 的正方形金属迹线组成，上迹线和下迹线通过金属化过孔相互连接。在体模和离体中测试了 3T MRI 基准标记程序，然后在人体 MRI 实验中评估了标记物的性能。还使用接近谐振器的温度传感器测试了射频安全性。
获得了厚度为 115μm、尺寸为 8×8mm 的柔性谐振器。在体模中的实验结果表明，在低背景翻转角（6-18°）下，共振标记物能够实现精确和快速的可视性，标记物附近的标记物与背景对比度和信噪比提高大于 10。温度分析显示特定吸收率增益为 1.3。临床研究进一步表明，使用我们设备的基准标记功能成功进行了活检程序。
这种无线灵活射频共振标记物的超薄和灵活结构提供了有效的、安全的磁共振可视化，具有在身体各个部位进行解剖标记和引导的高可行性。磁共振医学 80:361-370,2018。© 2017 国际磁共振学会。
