title: Overcoming the low relaxivity of gadofosveset at high field with spin locking.
abstract: The contrast agent gadofosveset, which binds reversibly to serum albumin, has a high longitudinal relaxivity at lower magnetic fields (≤3.0 T) but a much lower relaxivity at high fields. Spin locking is sensitive to macromolecular content; it is hypothesized that combining this technique with the albumin-binding properties of gadofosveset may enable increased relaxivity at high fields. In vitro measurements at 4.7 T found significantly higher spin-lock relaxation rates, R1ρ (1/T1ρ), when gadofosveset was serum albumin-bound than when unbound. R1ρ values for a nonbinding contrast agent (gadopentetate dimeglumine) in serum albumin were similar to those for unbound gadofosveset. R2 (1/T2) values were also significantly higher at 4.7 T for serum albumin-bound gadofosveset than for unbound. Spin locking at high field generates significantly higher relaxation rates for gadofosveset than conventional contrast agents and may provide a method for differentiating free and bound molecules at these field strengths.
authors.affiliation: Division of Medical Physics, University of Leeds, Leeds, UK.
authors.forename: O C
authors.initials: OC
authors.lastname: Richardson
authors.forename: M L J
authors.initials: ML
authors.lastname: Scott
authors.forename: S F
authors.initials: SF
authors.lastname: Tanner
authors.forename: J C
authors.initials: JC
authors.lastname: Waterton
authors.forename: D L
authors.initials: DL
authors.lastname: Buckley
mesh_terms: D000465:Algorithms; D016477:Artifacts; D003287:Contrast Media; D005682:Gadolinium; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009942:Organometallic Compounds; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D013113:Spin Labels; D005682:Gadolinium; C109932:gadofosveset trisodium