title: A general MRI-CEST ratiometric approach for pH imaging: demonstration of in vivo pH mapping with iobitridol.
abstract: Chemical exchange saturation transfer (CEST) is a novel contrast mechanism for magnetic resonance imaging (MRI). CEST MRI selectively saturates exchangeable protons that are transferred to MRI-detectable bulk water signal. MRI-CEST (pH)-responsive agents are probes able to map pH in the microenvironment in which they distribute. To minimize the confounding effects of contrast agent concentration, researchers have developed ratiometric CEST imaging, which investigates contrast agents containing multiple magnetically non-equivalent proton groups, whose prototropic exchange have different pH responses. However, conventional ratiometric CEST MRI imposes stringent requirements on the selection of CEST contrasts agents. In this study, a novel ratiometric pH MRI method based on the analysis of CEST effects under different radio frequency irradiation power levels was developed. The proposed method has been demonstrated using iobitridol, an X-ray contrast agent analog of iopamidol but containing a single set of amide protons, both in vitro and in vivo.
authors.affiliation: Institute of Biostructures and Bioimages (CNR) c/o Molecular Biotechnology Center and §Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino , Torino 10126, Italy.
authors.forename: Dario L
authors.initials: DL
authors.lastname: Longo
authors.forename: Phillip Zhe
authors.initials: PZ
authors.lastname: Sun
authors.forename: Lorena
authors.initials: L
authors.lastname: Consolino
authors.forename: Filippo C
authors.initials: FC
authors.lastname: Michelotti
authors.forename: Fulvio
authors.initials: F
authors.lastname: Uggeri
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry; D007668:Kidney / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D015394:Molecular Structure
chemical_list: D003287:Contrast Media; C093233:iobitridol; D007472:Iohexol