title: Bismuth labeling for the CT assessment of local administration of magnetic nanoparticles.
abstract: Many therapeutic applications of magnetic nanoparticles involve the local administration of nanometric iron oxide based materials as seeds for magnetothermia or drug carriers. A simple and widespread way of controlling the process using x-ray computed tomography (CT) scanners is desirable. The combination of iron and bismuth in one entity will increase the atenuation of x-rays, offering such a possibility. In order to check this possibility core-shell nanocrystals of iron oxide@bismuth oxide have been synthesized by an aqueous route and stabilized in water by polyethylene glycol (PEG), and we have evaluated their ability to generate contrast by CT and magnetic resonance imaging (MRI) to measure the radiopacity and proton relaxivities using phantoms. High-resolution scanning transmission electron microscopy (STEM) revealed that the material consists of a highly crystalline 8 nm core of maghemite and a 1 nm shell of bismuth atoms either isolated or clustered on the nanocrystal's surface. The comparison of μCT and MRI images of mice acquired in the presence of the contrast shows that when local accumulations of the magnetic nanoparticles take place, CT images are more superior in the localization of the magnetic nanoparticles than MRI images, which results in magnetic field inhomogeneity artifacts.
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, 28049, Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Veintemillas-Verdaguer
authors.forename: Y
authors.initials: Y
authors.lastname: Luengo
authors.forename: C J
authors.initials: CJ
authors.lastname: Serna
authors.forename: M
authors.initials: M
authors.lastname: Andrés-Vergés
authors.forename: M
authors.initials: M
authors.lastname: Varela
authors.forename: Macarena
authors.initials: M
authors.lastname: Calero
authors.forename: Ana
authors.initials: A
authors.lastname: Lazaro-Carrillo
authors.forename: Angeles
authors.initials: A
authors.lastname: Villanueva
authors.forename: A
authors.initials: A
authors.lastname: Sisniega
authors.forename: P
authors.initials: P
authors.lastname: Montesinos
authors.forename: M P
authors.initials: MP
authors.lastname: Morales