Institute of Biomedical Engineering, Bogazici University, Kandilli Campus, Istanbul, Turkey.
Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
Magn Reson Med. 2021 Sep;86(3):1786-1801. doi: 10.1002/mrm.28804. Epub 2021 Apr 16.
This work aims to fabricate RF antenna components on metallic needle surfaces using biocompatible polyester tubing and conductive ink to develop an active interventional MRI needle for clinical use at 0.55 Tesla.
A custom computer numeric control-based conductive ink printing method was developed. Based on electromagnetic simulation results, thin-film RF antennas were printed with conductive ink and used to fabricate a medical grade, 20-gauge (0.87 mm outer diameter), 90-mm long active interventional MRI needle. The MRI visibility performance of the active needle prototype was tested in vitro in 1 gel phantom and in vivo in 1 swine. A nearly identical active needle constructed using a 44 American Wire Gauge insulated copper wire-wound RF receiver antenna was a comparator. The RF-induced heating risk was evaluated in a gel phantom per American Society for Testing and Materials (ASTM) 2182-19.
The active needle prototype with printed RF antenna was clearly visible both in vitro and in vivo under MRI. The maximum RF-induced temperature rise of prototypes with printed RF antenna and insulated copper wire antenna after a 3.96 W/kg, 15 min. long scan were 1.64°C and 8.21°C, respectively. The increase in needle diameter was 98 µm and 264 µm for prototypes with printed RF antenna and copper wire-wound antenna, respectively.
The active needle prototype with conductive ink printed antenna provides distinct device visibility under MRI. Variations on the needle surface are mitigated compared to use of a 44 American Wire Gauge copper wire. RF-induced heating tests support device RF safety under MRI. The proposed method enables fabrication of small diameter active interventional MRI devices having complex geometries, something previously difficult using conventional methods.
本研究旨在使用生物相容性聚酯管和导电油墨在金属针表面制造射频（RF）天线元件，以开发用于 0.55T 临床应用的有源介入式 MRI 针。
开发了一种基于定制计算机数控的导电油墨打印方法。根据电磁模拟结果，使用导电油墨打印薄膜 RF 天线，并用于制造一种医疗级、20 号（0.87 毫米外径）、90 毫米长的有源介入式 MRI 针。在 1 个凝胶体体模和 1 只猪体内对有源针原型的 MRI 可视性性能进行了体外和体内测试。一个使用 44 号美国线规（AWG）绝缘铜丝绕制 RF 接收器天线构建的有源针作为对照。根据美国材料与试验协会（ASTM）标准 2182-19，在凝胶体体模中评估了 RF 诱导加热风险。
在 MRI 下，带有印刷 RF 天线的有源针原型在体外和体内均清晰可见。在 3.96 W/kg、15 分钟长的扫描后，带有印刷 RF 天线和绝缘铜丝天线的原型的最大 RF 诱导温升分别为 1.64°C 和 8.21°C。带有印刷 RF 天线和铜丝绕制天线的原型的针直径增加分别为 98µm 和 264µm。
带有导电油墨印刷天线的有源针原型在 MRI 下提供了明显的设备可视性。与使用 44 号 AWG 铜丝相比，针表面的变化得到了缓解。RF 诱导加热测试支持 MRI 下设备的射频安全性。该方法可用于制造具有复杂几何形状的小直径有源介入式 MRI 设备，这是以前使用传统方法难以实现的。
