title: Feasibility of concurrent dual contrast enhancement using CEST contrast agents and superparamagnetic iron oxide particles.
abstract: A major challenge for cellular and molecular MRI is to study interactions between two different cell populations or biological processes. We studied the possibility to simultaneously image contrast agents based on two different MRI contrast mechanisms: chemical exchange saturation transfer (CEST) and enhancement of T2 relaxation. Various amounts of superparamagnetic iron oxide (SPIO) nanoparticles were mixed with a fixed concentration (250 microM) of the CEST agent poly-L-lysine. T2 maps, CEST maps, and frequency-dependent saturation spectra were then measured. Color-coded overlay maps demonstrated the feasibility of concurrent dual contrast enhancement. We found that at concentrations lower than 5 microg(Fe)/mL both contrast agents can be imaged simultaneously. At higher concentrations, the iron-based agent can be used to "shut off" the signal arising from the CEST agent. These initial findings are a first step toward using dual CEST/T2 contrast imaging for studying multiple cellular or molecular targets simultaneously in vivo.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Neurosection, Baltimore, Maryland 21231, USA. assaf@mri.jhu.edu
authors.forename: Assaf A
authors.initials: AA
authors.lastname: Gilad
authors.forename: Hanneke W M
authors.initials: HW
authors.lastname: van Laarhoven
authors.forename: Michael T
authors.initials: MT
authors.lastname: McMahon
authors.forename: Piotr
authors.initials: P
authors.lastname: Walczak
authors.forename: Arend
authors.initials: A
authors.lastname: Heerschap
authors.forename: Michal
authors.initials: M
authors.lastname: Neeman
authors.forename: Peter C M
authors.initials: PC
authors.lastname: van Zijl
authors.forename: Jeff W M
authors.initials: JW
authors.lastname: Bulte
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D005290:Ferric Compounds / Q000008:administration & dosage*; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008280:Magnetics; D019047:Phantoms, Imaging; D011107:Polylysine / Q000008:administration & dosage*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide; D011107:Polylysine