title: (15)N Heteronuclear Chemical Exchange Saturation Transfer MRI.
abstract: A two-step heteronuclear enhancement approach was combined with chemical exchange saturation transfer (CEST) to magnify (15)N MRI signal of molecules through indirect detection via water protons. Previous CEST studies have been limited to radiofrequency (rf) saturation transfer or excitation transfer employing protons. Here, the signal of (15)N is detected indirectly through the water signal by first inverting selectively protons that are scalar-coupled to (15)N in the urea molecule, followed by chemical exchange of the amide proton to bulk water. In addition to providing a small sensitivity enhancement, this approach can be used to monitor the exchange rates and thus the pH sensitivity of the participating (15)N-bound protons.
authors.affiliation: F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Zeng
authors.affiliation: F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States.
authors.forename: Jiadi
authors.initials: J
authors.lastname: Xu
authors.affiliation: F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States.
authors.forename: Nirbhay N
authors.initials: NN
authors.lastname: Yadav
authors.affiliation: F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States.
authors.forename: Michael T
authors.initials: MT
authors.lastname: McMahon
authors.forename: Bradley
authors.initials: B
authors.lastname: Harden
authors.forename: Dominique
authors.initials: D
authors.lastname: Frueh
authors.affiliation: F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States.
authors.forename: Peter C M
authors.initials: PC
authors.lastname: van Zijl
mesh_terms: D008279:Magnetic Resonance Imaging / Q000379:methods*; D009587:Nitrogen Isotopes / Q000737:chemistry*; D011522:Protons; D014867:Water / Q000737:chemistry
chemical_list: D009587:Nitrogen Isotopes; C000615243:Nitrogen-15; D011522:Protons; D014867:Water