Magnetic Particle / Magnetic Resonance Imaging: In-Vitro MPI-Guided Real Time Catheter Tracking and 4D Angioplasty Using a Road Map and Blood Pool Tracer Approach

Abstract

PurposeIn-vitro evaluation of the feasibility of 4D real time tracking of endovascular devices and stenosis treatment with a magnetic particle imaging (MPI) / magnetic resonance imaging (MRI) road map approach and an MPI-guided approach using a blood pool tracer.Materials and MethodsA guide wire and angioplasty-catheter were labeled with a thin layer of magnetic lacquer. For real time MPI a custom made software framework was developed. A stenotic vessel phantom filled with saline or superparamagnetic iron oxide nanoparticles (MM4) was equipped with bimodal fiducial markers for co-registration in preclinical 7T MRI and MPI. In-vitro angioplasty was performed inflating the balloon with saline or MM4. MPI data were acquired using a field of view of 37.3×37.3×18.6 mm3 and a frame rate of 46 volumes/sec. Analysis of the magnetic lacquer-marks on the devices were performed with electron microscopy, atomic absorption spectrometry and micro-computed tomography.ResultsMagnetic marks allowed for MPI/MRI guidance of interventional devices. Bimodal fiducial markers enable MPI/MRI image fusion for MRI based roadmapping. MRI roadmapping and the blood pool tracer approach facilitate MPI real time monitoring of in-vitro angioplasty. Successful angioplasty was verified with MPI and MRI. Magnetic marks consist of micrometer sized ferromagnetic plates mainly composed of iron and iron oxide.Conclusions4D real time MP imaging, tracking and guiding of endovascular instruments and in-vitro angioplasty is feasible. In addition to an approach that requires a blood pool tracer, MRI based roadmapping might emerge as a promising tool for radiation free 4D MPI-guided interventions.

Magnetic Particle Imaging (MPI): Experimental Quantification of Vascular Stenosis Using Stationary Stenosis Phantoms

“…For image guidance of interventions, real-time imaging has to be combined with (quasi) real-time reconstruction [54]. First results towards real time MPI were already presented recently by Salamon et al [55]. For MPI-guided interventions the safety of devices like guide wires and stents also has to be considered [56].…”

The relaxation wall: experimental limits to improving MPI spatial resolution by increasing nanoparticle core size

“…MPI is best compared to gold-standard tracer imaging techniques, such as nuclear medicine, but without the limitations of radiation safety or radionuclide half-life for longitudinal imaging. As such, MPI shows excellent promise for clinical applications such as angiography (Haegele et al 2012; Salamon et al 2016), stem cell tracking and vitality assessment (Fidler et al 2015; Them et al 2016; Zheng, Vazin, et al 2015; Zheng, von See, et al 2016), brain perfusion (Orendorff et al 2016), lung perfusion (Zhou et al 2016),lung ventilation (Nishimoto et al 2015), cancer imaging (E. Yu et al 2016), and localized hyperthermia (Murase, Aoki, et al 2015; Hensley et al 2016).…”

Simultaneous Magnetic Particle Imaging and Navigation of large superparamagnetic nanoparticles in bifurcation flow experiments

“…1,2 The highest sensitivity is achieved with particles in the magnetic core size range of 15 nm to 30 nm. 3,4 Due to different signal characteristics for different particle types, it is even possible to distinguish between different particle types with the multi-contrast approach introduced by Rahmer et al 5 Lately, MPI has been utilized to track balloon catheters for stenosis clearing 6,7 and to navigate magnetically coated catheters through difficult bifurcations 8 . To this end, a soft-magnetic sphere has been attached to the catheter.…”