Bimodal Interventional Instrument Markers for Magnetic Particle Imaging and Magnetic Resonance Imaging—A Proof-of-Concept Study

Abstract

The purpose of this work was to develop instrument markers that are visible in both magnetic particle imaging (MPI) and magnetic resonance imaging (MRI). The instrument markers were based on two different magnetic nanoparticle types (synthesized in-house KLB and commercial Bayoxide E8706). Coatings containing one of both particle types were fabricated and measured with a magnetic particle spectrometer (MPS) to estimate their MPI performance. Coatings based on both particle types were then applied on a segment of a nonmetallic guidewire. Imaging experiments were conducted using a commercial, preclinical MPI scanner and a preclinical 1 tesla MRI system. MPI image reconstruction was performed based on system matrices measured with dried KLB and Bayoxide E8706 coatings. The bimodal markers were clearly visible in both methods. They caused circular signal voids in MRI and areas of high signal intensity in MPI. Both the signal voids as well as the areas of high signal intensity were larger than the real marker size. Images that were reconstructed with a Bayoxide E8706 system matrix did not show sufficient MPI signal. Instrument markers with bimodal visibility are essential for the perspective of monitoring cardiovascular interventions with MPI/MRI hybrid systems.

Bare-Metal Stent Tracking with Magnetic Particle Imaging

“…Therefore, the instruments are coated with nanoparticle-containing varnishes. 5 , 11 , 12 , 20 This approach leads to sufficient imaging properties but changes the mechanical and biocompatible characteristics of the instruments. Thus, the use of commercially available medical products with MPI signal generating characteristics is very promising regarding the clinical application of MPI.…”

“…7,9,10 To overcome this limitation, endovascular devices like stents, catheters and guidewires have been modified with dedicated marking technologies to make them visible in MPI. 5,[11][12][13] SPION-coatings as well as polymerintegrated nanoparticles have been introduced as visualization techniques. However, both approaches change the mechanical properties of the devices and require sophisticated production steps.…”