First multimodal embolization particles being visible in MRI and CT

Purpose: To develop and test the first multimodal embolization particles being visible within CT and MRI. Its usage might be beneficial within multimodality angiography setups, therapy control, long-term follow-up of embolization therapy, future transition to interventional MRI and research of novel embolization concepts.
Methods and Materials: CT visible iodine was combined with MRI visible iron in a macroparticle (diameter 50-250 µm). Its core - consisting of copolymerized monomer MAOETIB [2-methacryloyloxyethyl(2,3,5-triiodobenzoate)] - was coated with paramagnetic iron oxide nanoparticles (USPIO). After ex-vivo testing, including SNR measurements (n=5), its ability to embolize tissue was tested in an established tumor embolization model in rats (2) and rabbits (5). X-ray angiography, CT and MR imaging was performed on clinical scanners (Dual-source Definition CT, 3 Tesla Magnetom Tim Trio MRI, Siemens) before, during and after application of particles to the catheterized renal artery. Histology was prepared.
Results: The particles provided a sufficient image contrast in both CT (SNR: 14±4) and MRI (SNR: 14±1). Successful embolization of renal tissue was confirmed by particles residing within the kidney as seen in corresponding areas in MRI and CT. Histology allowed a direct visualization of the residing particles as well as associated thrombosis in kidney arteries. Successful embolization was confirmed by inflammation and necrosis in treated kidneys while the control kidneys were unaltered.
Conclusion: A multimodality embolization material was successfully developed and tested in animal models. Its consistence of clinically used substances might ease approval.