Generating contrast in hyperpolarized 13C MRI using ligand-receptor interactions.
We report the imaging of β-cyclodextrin-benzoic acid binding at 14T using hyperpolarized (13)C magnetic resonance (MR). Benzoic acid was polarized using a dynamic nuclear polarization (DNP) approach and combined with β-cyclodextrin in aqueous solution. As anticipated, decreases in the spin-lattice relaxation constant (T(1)) were observed with decreases in the ligand-receptor ratio. The calculated log K was approximately 1.7, similar to previously reported binding constants. Hyperpolarized [1-(13)C] benzoic acid was used to interrogate solutions of variable β-cyclodextrin concentrations, with the mixtures imaged at 14T using a 3D frequency-selective MR sequence. Differences in β-cyclodextrin concentration were easily visualized. These results suggest that hyperpolarized (13)C MR could be used in vivo to determine the presence and density of receptors for a given ligand-receptor pair.
Department of Radiology, University of California San Francisco, San Francisco, USA.
Kayvan R
KR
Keshari
John
J
Kurhanewicz
Jeffrey M
JM
Macdonald
David M
DM
Wilson
D019817:Benzoic Acid / Q000737:chemistry*; D002247:Carbon Isotopes; D015350:Contrast Sensitivity; D008024:Ligands; D008279:Magnetic Resonance Imaging / Q000379:methods*; D047392:beta-Cyclodextrins / Q000737:chemistry*
D002247:Carbon Isotopes; D008024:Ligands; D047392:beta-Cyclodextrins; D019817:Benzoic Acid; C031215:betadex