title: Exchange-mediated contrast agents for spin-lock imaging.
abstract: Measurements of relaxation rates in the rotating frame with spin-locking techniques are sensitive to substances with exchanging protons with appropriate chemical shifts. The authors develop a novel approach to exchange-rate selective imaging based on measured T(1ρ) dispersion with applied locking field strength, and demonstrate the method on samples containing the X-ray contrast agent Iohexol with and without cross-linked bovine serum albumin. T(1ρ) dispersion of water in the phantoms was measured with a Varian 9.4-T magnet by an on-resonance spin-locking pulse with fast spin-echo readout, and the results used to estimate exchange rates. The Iohexol phantom alone gave a fitted exchange rate of ~1 kHz, bovine serum albumin alone was ~11 kHz, and in combination gave rates in between. By using these estimated rates, we demonstrate how a novel spin-locking imaging method may be used to enhance contrast due to the presence of a contrast agent whose protons have specific exchange rates.
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232-2310, USA. jared.g.cobb@vanderbilt.edu
authors.forename: Jared G
authors.initials: JG
authors.lastname: Cobb
authors.forename: Jingping
authors.initials: J
authors.lastname: Xie
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Gochberg
authors.forename: John C
authors.initials: JC
authors.lastname: Gore
mesh_terms: D003287:Contrast Media / Q000737:chemistry; D007089:Image Enhancement / Q000379:methods*; D007472:Iohexol / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012709:Serum Albumin / Q000737:chemistry*; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D012709:Serum Albumin; D013113:Spin Labels; D007472:Iohexol