title: Improving detection specificity of iron oxide nanoparticles (IONPs) using the SWIFT sequence with long T(2) suppression.
abstract: In order to improve the detection specificity of iron oxide nanoparticles (IONPs) delivered to tumors, we embedded saturation pulses into the sweep imaging using Fourier transformation (SWIFT) sequence to suppress long T(2) tissues and fat. Simulation of the Bloch equation was first conducted to study behavior of the saturation pulses of various lengths under different T(2) and off-resonance conditions. MR experiments were then conducted using in vivo mouse xenografts and a phantom consisting of IONPs, vegetable oil, and explanted tumor specimen, without and with long T(2) suppression under a 7T magnetic field. For the in vivo study, arginine-glycine-aspartate (RGD) coated 10nm IONPs (RGD-IONPs) were delivered to tumors implanted in nude mice through both intra-tumor and intravenous injections. Histological studies confirmed that RGD-IONPs efficiently homed to tumors through RGD-integrin interaction. Compared to conventional SWIFT, the proposed method resulted in sufficient suppression on long T(2) species but less influence on short T(2) species. For both the in vivo and ex vivo studies, significantly improved contrast-to-noise ratio (CNR) was achieved between the IONPs and the long T(2) species.
authors.affiliation: Department of Physics and Astronomy, University of Georgia, Athens, US; BioImaging Research Center (BIRC), University of Georgia, Athens, US.
authors.forename: Luning
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Georgia, Athens, US.
authors.forename: Wei
authors.initials: W
authors.lastname: Tang
authors.affiliation: Department of Chemistry, University of Georgia, Athens, US.
authors.forename: Zipeng
authors.initials: Z
authors.lastname: Zhen
authors.affiliation: Department of Chemistry, University of Georgia, Athens, US.
authors.forename: Hongming
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of Georgia, Athens, US; BioImaging Research Center (BIRC), University of Georgia, Athens, US.
authors.forename: Jin
authors.initials: J
authors.lastname: Xie
authors.affiliation: Department of Physics and Astronomy, University of Georgia, Athens, US; BioImaging Research Center (BIRC), University of Georgia, Athens, US. Electronic address: qzhao@physast.uga.edu.
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000818:Animals; D001120:Arginine; D001224:Aspartic Acid; D045744:Cell Line, Tumor; D003287:Contrast Media; D005583:Fourier Analysis; D005998:Glycine; D064593:Heterografts; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008325:Mammary Neoplasms, Experimental / Q000175:diagnosis* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles; D001224:Aspartic Acid; D001120:Arginine; D005998:Glycine
keywords: IONPs; Iron oxide nanoparticles; Long T(2) suppression; SWIFT; Sweep imaging with Fourier transformation; Tumor