Feasibility of concurrent dual contrast enhancement using CEST contrast agents and superparamagnetic iron oxide particles.
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.
Gilad
Assaf A
AA
Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Neurosection, Baltimore, Maryland 21231, USA. assaf@mri.jhu.edu
van Laarhoven
Hanneke W M
HW
McMahon
Michael T
MT
Walczak
Piotr
P
Heerschap
Arend
A
Neeman
Michal
M
van Zijl
Peter C M
PC
Bulte
Jeff W M
JW
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
D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide; D011107:Polylysine