title: Magnetite nanoparticles can be coupled to microbubbles to support multimodal imaging.
abstract: Microbubbles (MBs) are commonly used as injectable ultrasound contrast agent (UCA) in modern ultrasonography. Polymer-shelled UCAs present additional potentialities with respect to marketed lipid-shelled UCAs. They are more robust; that is, they have longer shelf and circulation life, and surface modifications are quite easily accomplished to obtain enhanced targeting and local drug delivery. The next generation of UCAs will be required to support not only ultrasound-based imaging methods but also other complementary diagnostic approaches such as magnetic resonance imaging or computer tomography. This work addresses the features of MBs that could function as contrast agents for both ultrasound and magnetic resonance imaging. The results indicate that the introduction of iron oxide nanoparticles (SPIONs) in the poly(vinyl alcohol) shell or on the external surface of the MBs does not greatly decrease the echogenicity of the host MBs compared with the unmodified one. The presence of SPIONs provides enough magnetic susceptibility to the MBs to accomplish good detectability both in vitro and in vivo. The distribution of SPIONs on the shell and their aggregation state seem to be key factors for the optimization of the transverse relaxation rate.
authors.affiliation: Department of Clinical Science, Intervention and Technology at Karolinska Institutet, Division of Medical Imaging and Technology, Stockholm, Sweden.
authors.forename: Torkel B
authors.initials: TB
authors.lastname: Brismar
authors.forename: Dmitry
authors.initials: D
authors.lastname: Grishenkov
authors.forename: Björn
authors.initials: B
authors.lastname: Gustafsson
authors.forename: Johan
authors.initials: J
authors.lastname: Härmark
authors.forename: Asa
authors.initials: A
authors.lastname: Barrefelt
authors.forename: Satya V V N
authors.initials: SV
authors.lastname: Kothapalli
authors.forename: Silvia
authors.initials: S
authors.lastname: Margheritelli
authors.forename: Letizia
authors.initials: L
authors.lastname: Oddo
authors.forename: Kenneth
authors.initials: K
authors.lastname: Caidahl
authors.forename: Hans
authors.initials: H
authors.lastname: Hebert
authors.forename: Gaio
authors.initials: G
authors.lastname: Paradossi
mesh_terms: D003287:Contrast Media / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D058185:Magnetite Nanoparticles / Q000737:chemistry; D045423:Microbubbles; D010316:Particle Size; D014057:Tomography, X-Ray Computed / Q000295:instrumentation
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles