Magnetic Particle Imaging–Guided Stenting

Abstract

Purpose:To assess the feasibility of magnetic particle imaging (MPI) to guide stenting in a phantom model. Materials and Methods: MPI is a new tomographic imaging method based on the background-free magnetic field detection of a tracer agent composed of superparamagnetic iron oxide nanoparticles (SPIOs). All experiments were conducted on a custom-built MPI scanner (field of view: 29-mm diameter, 65-mm length; isotropic spatial resolution 1–1.5-mm). Stenosis phantoms (n=3) consisted of polyvinyl chloride (PVC) tubes (8-mm inner diameter) prepared with centrally aligned cable binders to form a ~50% stenosis. A dedicated image reconstruction algorithm allowed precise tracking of endovascular instruments at 8 frames/s with a latency time of ~115 ms. A custom-made MPI-visible lacquer was used to manually label conventional guidewires, balloon catheters, and stainless steel balloon-expandable stents. Vascular stenoses were visualized by injecting a diluted SPIO tracer (ferucarbotran, 10 mmol iron/L) into the vessel phantoms. Balloon angioplasty and stent placement were performed by inflating balloon catheters and stent delivery balloons with diluted ferucarbotran. Results: After deployment of the stent, the markers on its ends were clearly visible. The applied lacquer markers were thin enough to not relevantly alter gliding properties of the devices while withstanding friction during the experiments. Placing an optimized flexible lacquer formulation on the preexisting radiopaque stent markers provided enough stability to withstand stent expansion. Final MPA confirmed successful stenosis treatment, facilitated by the disappearance of the lacquer markers on the stent due to differences in SPIO concentration. Thus, the in-stent lumen could be visualized without interference by the signal from the markers. Conclusion: Near real-time visualization of MPI-guided stenting of stenoses in a phantom model is feasible. Optimized MPI-visible markers can withstand the expansion process of stents.

Long circulating tracer tailored for magnetic particle imaging

“…Several commercially available SPIONs have been studied as MPI tracers. Ferucarbotran (an off-brand version of Resovist ® ) is a commercially available SPION contrast agent developed specifically for MRI that is commonly used for MPI studies 13 , 14 . However, it has been suggested that only 3% of the total iron mass from Resovist ® contributes to the MPI signal due to particle-particle interaction within carboxydextran coated core 1 .…”

Heating of an Aortic Stent for Coarctation Treatment During Magnetic Particle Imaging and Magnetic Resonance Imaging—A Comparative In Vitro Study

“…In contrast to CT and MRI, the stent lumen can be assessed without artifacts in MPI [ 8 ]. Recently, Herz et al demonstrated the potential of MPI to guide percutaneous transluminal angioplasties of vascular stenoses [ 9 ]. Since both, MPI and MRI use oscillating magnetic fields, the heating of metallic objects is a potential risk that needs to be investigated more closely.…”

Combining magnetic particle imaging and magnetic fluid hyperthermia for localized and image-guided treatment

“…This means that MPI is a high signal to noise ratio (SNR) imaging platform like nuclear medicine [24,31]. MPI has demonstrated promise for applications such as angiography [32,33], stem cell tracking [34][35][36], brain perfusion [37,38], lung perfusion [39], lung ventilation [40,41], cancer imaging [42], gut bleed detection [43], remote magnetic actuation and magnetic catheter steering and guidance [44][45][46][47], and localized MFH [21,22,48,49]. Selected MPI images are shown in Figure 1.…”