title: Transverse relaxation of cells labeled with magnetic nanoparticles.
abstract: We describe the NMR relaxation properties of magnetically labeled cells. The cells are labeled with magnetic nanoparticles (SPIO, USPIO), which generate susceptibility contrast. The geometry of the labeled cells and the surrounding tissue is considered. We assume that the magnetic nanoparticles accumulate to form a magnetic core of radius RC inside the cell. The correlation time tau, which describes the motion of spins around this core, is analyzed. Using the strong collision approach, explicit expressions are derived for the transverse relaxation rate R2* for tissue containing labeled cells as a function of the core radius, the diffusion coefficient, and the concentration of the nanoparticles. The predictions of this model agree well with numerical simulations and experimental data.
authors.affiliation: Bayerische Julius-Maximilians-Universität Würzburg, Institut für Experimentelle Physik 5, Am Hubland, 97074 Würzburg, Germany. ziener@physik.uni-wuerzburg.de
authors.forename: C H
authors.initials: CH
authors.lastname: Ziener
authors.forename: W R
authors.initials: WR
authors.lastname: Bauer
authors.forename: P M
authors.initials: PM
authors.lastname: Jakob
mesh_terms: D002451:Cell Compartmentation; D002478:Cells, Cultured; D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D007501:Iron; D008264:Macrophages / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D058185:Magnetite Nanoparticles; D008962:Models, Theoretical; D036103:Nanotechnology; D010087:Oxides; D013194:Staining and Labeling / Q000379:methods; D013234:Stem Cells / Q000378:metabolism
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide