Objective: Interventional ultrasound imaging is a prerequisite for guiding implants and treatment within the hearts and blood vessels. Due to limitations on the catheter's diameter, interventional ultrasonic transducers have side-looking structures although forward-looking imaging may provide more intuitive and real time guidance in treating diseased sites ahead of catheters. To address the issue, a magnetically actuated forward-looking interventional ultrasound imaging device is implemented for the first time. Methods: A forward-looking catheter containing a 1 mm ring type focused 35 MHz ultrasound transducer and a micro magnet, was fabricated. For imaging, the transducer was placed at the center of four electromagnetic coils positioned on four sides of a squared acrylic housing. By modifying the magnetic field, the catheter tip could be remotely translated for sector scanning. Results: The scanning angle could reach up to 3° in 1 Hz with 15 mT, while wider angles of 5° could be achieved with a higher magnetic field of 25 mT for ex-vivo imaging. The position of the transducer could be detected by monitoring the motion with a CCD camera, mimicking clinical X-ray imaging. In the wire target and tissue mimicking phantom studies, the measured hole size, spatial resolution and distance between wires by the proposed system were comparable with the values from a linear scanner. Multi-frame real time data acquisition was demonstrated via ex-vivo imaging on a pig's coronary artery. Conclusion/Significance: The feasibility of magnetically actuated forward-looking interventional ultrasound imaging was demonstrated. The remote-controlled scanning method may allow to simplify the structures of forward-looking interventional ultrasound imaging catheters.

中文翻译：

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磁驱动前视介入超声成像：可行性研究

目的：介入超声成像是指导心脏和血管内植入物和治疗的先决条件。由于导管直径的限制，介入式超声换能器具有侧视结构，尽管前视成像可以在导管之前治疗病变部位提供更直观和实时的指导。为了解决这个问题，首次实现了磁驱动前视介入超声成像设备。方法：制造了一个包含 1 mm 环形聚焦 35 MHz 超声换能器和微磁体的前视导管。为了成像，将换能器放置在位于方形丙烯酸外壳四侧的四个电磁线圈的中心。通过改变磁场，导管尖端可以远程平移以进行扇形扫描。结果：扫描角度在 1 Hz 下可以达到 3°，15 mT，而更宽的角度可以在 25 mT 的更高磁场下实现，用于离体成像。传感器的位置可以通过用 CCD 摄像机监测运动来检测，模拟临床 X 射线成像。在导线目标和组织模拟体模研究中，所提出的系统测量的孔尺寸、空间分辨率和导线之间的距离与线性扫描仪的值相当。通过对猪冠状动脉的离体成像证明了多帧实时数据采集。结论/意义：证明了磁驱动前视介入超声成像的可行性。