强磁场在介入医学中的应用

Applications of high magnetic field in interventional medical treatment

强磁场技术被越来越多地应用于介入治疗中.强磁场介入技术,即通过体外可变磁场遥控操纵位于体内带有磁性物质(药物或导管或支架等)来实现介入诊疗的大型集成化医疗技术.通过该技术可以实现在定向精准给药和快速定位治疗,这给治疗带来了极大的便利,也提高了治疗效率.用于心脏血管治疗的心脏介入磁导航系统是近年来兴起的新型介入导航系统,其通过外源性磁场指引下的遥控操纵技术,可完全避免传统手工操作引起的心脏穿孔等严重并发症,大幅缩短培训周期、减少X射线辐射,通过互联网系统更可实现远程介入诊疗和专家系统.磁性纳米颗粒由于其本征的磁性,既可以作为药物载体在强磁场作用下定向施药,又可以用作MRI的T2显影剂,作为介入治疗的辅助手段.通过类似核壳结构的精巧纳米结构挂载其余影像学显影剂,可以制备磁性纳米颗粒多重显影剂.本文将详细介绍近年来使用磁性纳米颗粒制备MRI用T1-T2联合显影剂以及MRI和PET/SPECT联合显影剂的研究进展.此外,基于磁共振成像的介入治疗技术以其独特的优势在医学介入治疗领域得到广泛关注.相应的技术手段大体上可以分为这样的几个方面:电磁非兼容介入治疗,即将治疗器械放置在远离磁共振的区域进行手术,之后将病人移入成像区成像观测;电磁兼容介入治疗,即应用电磁兼容材料制造手术器械,将手术装置和驱动装置都设计成电磁兼容模式;电磁驱动介入治疗,即利用磁共振梯度或者射频磁场的力学驱动特性来驱动手术器械,实现驱动和治疗全部自动化.

High magnetic field technology is increasingly used in interventional therapy. The strong magnetic field-involved intervention technology is a large-scale, integrated medical technology in which an in vitro, variable magnetic field is used to remotely control a magnetic substance(a drug, a catheter, or a stent, etc.) located in the body to realize interventional treatment. Through this technology, accurate targeted drug delivery and rapid positioning therapy can be achieved, which brings great convenience to the treatment and also improves the treatment efficiency and accuracy. The cardiac interventional magnetic navigation system for cardiovascular treatment is such a new type of interventional navigation system that has emerged in recent years. Through the remote-control manipulation technique guided by the external magnetic field, it can completely avoid the severe serious complications such as cardiac perforation caused by the traditional manual operation, shortening the training cycle and reducing the X-ray radiation to doctors and patients. This technology can further realize remote interventional treatment through the Internet system and expert system. Due to its intrinsic high magnetic performance, the magnetic nanoparticles can be directly used as drug delivery system under high magnetic field, and also as negative contrast of MRI. Combining with the ingenious nanostructures such as core—shell structure, the dual contrast of MRI and other iconography method can be successfully developed. In this paper, some latest research results of dual T1-T2 contrast of MRI and dual contrast of MRI and PET/SPECT have been reviewed. Moreover, the MRI-guided intervention technique has aroused comprehensive attention in the image-guided intervention scope. The corresponding methods can be roughly divided into following aspects:(a) MRI non-compatible intervention, which places the operation apparatus in a region far away from the MRI system and then the patient can be transferred to the imaging area;(b) MRI-compatible intervention, which applied compatible materials to fabricate the operation apparatus and actuator device;(c) MRI-powered intervention, which uses gradient field or RF field-actuated apparatus to realize automatic operation.