Magnetic resonance imaging and/or spectroscopy contrast agents and methods of use thereof
The presently disclosed subject matter demonstrates that a spin state which has zero magnetic resonance signal, but an extremely long lifetime, can be used to store magnetization, which can then be recovered into an observable transition. Coupled with hyperpolarization techniques, this permits the preparation of a wide range of contrast agent molecules for use in magnetic resonance imaging (MRI) techniques that have long effective relaxation time.
1. A method of providing a contrast agent for magnetic resonance imaging (MRI) or magnetic resonance spectroscopy, the method comprising:
providing a precursor molecule comprising two J-coupled, non-zero-spin, non-equivalent nuclei, wherein said precursor molecule is chemically convertible to a contrast agent molecule wherein the two J-coupled, non-zero-spin, non-equivalent nuclei are converted to equivalent nuclei;
hyperpolarizing the precursor molecule to provide a hyperpolarized precursor molecule;
applying one or more radiofrequency pulse(s) to the hyperpolarized precursor molecule to create one or both of a non-equilibrium αβ nuclear spin state population and a non-equilibrium βα nuclear spin state population; and
chemically converting the hyperpolarized precursor molecule into a contrast agent molecule by converting the two J-coupled, non-zero-spin, non-equivalent nuclei to two J-coupled, non-zero-spin, equivalent nuclei, wherein the contrast agent molecule comprises a non-equilibrium nuclear singlet spin state population and is chemically convertible to a detection molecule wherein said equivalent nuclei are converted to non-equivalent nuclei.
2. The method of claim 1 , wherein the contrast agent molecule is chemically convertible to the detection molecule under physiological conditions.
3. The method of claim 1 , wherein the contrast agent molecule is converted to the detection molecule via contact with water.
4. The method of claim 1 , wherein the contrast agent molecule is converted to the detection molecule via an enzymatic reaction.
5. The method of claim 1 , wherein the contrast agent molecule is in chemical equilibrium with the precursor molecule or the detection molecule.
6. The method of claim 5 , wherein the chemical equilibrium is perturbed to interconvert the contrast agent molecule and the hyperpolarized precursor molecule, the contrast agent molecule and the detection molecule, or both.
7. The method of claim 1 , wherein the precursor molecule and the detection molecule have the same molecular structure.
8. The method of claim 1 , wherein the two J-coupled, non-zero-spin non-equivalent nuclei of the precursor molecule are selected from the group consisting of 1 H, 13 C, 15 N and 31 P.
9. The method of claim 1 , wherein the hyperpolarizing is performed by dynamic nuclear polarization (DNP).
10. The method of claim 1 , wherein chemically converting the hyperpolarized precursor molecule into the contrast agent molecule comprises dehydrating the hyperpolarized precursor molecule.
11. The method of claim 10 , wherein the dehydrating is accelerated or slowed by changing the pH of an aqueous solvent in which the hyperpolarized precursor molecule is dissolved.
12. A method of providing a contrast agent for magnetic resonance imaging (MRI) or magnetic resonance spectroscopy, the method comprising:
providing a precursor molecule comprising two J-coupled, non-zero-spin, non-equivalent nuclei, wherein said precursor molecule is chemically convertible to a contrast agent molecule wherein the two J-coupled, non-zero-spin, non-equivalent nuclei are converted to equivalent nuclei;
hyperpolarizinq the precursor molecule to provide a hyperpolarized precursor molecule;
applying one or more radiofrequency pulse(s) to the hyperpolarized precursor molecule to create one or both of a non-equilibrium αβ nuclear spin state population and a non-equilibrium βα nuclear spin state population; and
chemically converting the hyperpolarized precursor molecule into a contrast agent molecule by converting the two J-coupled, non-zero-spin, non-equivalent nuclei to two J-coupled, non-zero-spin, equivalent nuclei, wherein the contrast agent molecule comprises a non-equilibrium nuclear singlet spin state population and is chemically convertible to a detection molecule wherein said equivalent nuclei are converted to non-equivalent nuclei;
further wherein one or both of the precursor molecule and the detection molecule is the monohydrate of diacetyl.
13. The method of claim 1 , wherein the contrast agent molecule is selected from the group consisting of diacetyl, oxolin, alendronate, amitryptyline, nortriptyline, succinate, fumarate, maleimide, catechol, naphthalene, naphthoquinone, phenylbutazone, pyridazine, phthalazine, dopamine, L-dihydroxyphenylalanine (L-DOPA) and derivatives thereof.
14. The method of claim 1 , wherein the two J-coupled, non-zero-spin, equivalent nuclei of the contrast agent molecule are free of directly bonded hydrogen atoms.
15. The method of claim 1 , wherein the two J-coupled, non-zero-spin, equivalent nuclei of the contrast agent molecule are directly bonded to hydrogen atoms and are J-coupled to two other, additional equivalent nuclei, wherein the two other, additional equivalent nuclei are free of directly bonded hydrogen atoms, and whereby application of one or more radiofrequency pulse(s) can transfer a spin state population between the two J-coupled, non-zero-spin, equivalent nuclei and the two other, additional equivalent nuclei.
16. The method of claim 1 , further comprising incorporating the contrast agent molecule into a pharmaceutically acceptable carrier to provide a pharmaceutically acceptable formulation suitable for administration to a subject.
17. The method of claim 16 , wherein the subject is a mammal.
18. The method of claim 1 , further comprising encapsulating the contrast agent molecule into a biodegradable delivery format that prevents water contact with the contrast agent molecule prior to complete or partial biodegradation of said delivery format.
19. The method of claim 1 , wherein the non-equilibrium nuclear singlet spin state population can persist for a time that is substantially greater than T 1 .
20. The method of claim 19 , wherein the non-equilibrium nuclear singlet spin state population can persist for a time that is greater than 3 times T 1 .
21. The method of claim 20 wherein the non-equilibrium nuclear singlet spin state population can persist for a time that is greater than 10 times T 1 .
22. The method of claim 19 , wherein the non-equilibrium nuclear singlet spin state population can persist for a time that is between about 3 times T 1 and about 10 times T 1 .
23. A method of imaging a target, the method comprising:
providing a contrast agent molecule having a non-equilibrium singlet state nuclear spin population, wherein providing the contrast agent molecule comprises:
providing a precursor molecule comprising two J-coupled, non-zero-spin, non-equivalent nuclei, wherein said precursor molecule is chemically convertible to a contrast agent molecule wherein the two J-coupled, non-zero-spin, non-equivalent nuclei are converted to equivalent nuclei;
hyperpolarizing the precursor molecule to provide a hyperpolarized precursor molecule;
applying one or more radiofrequency pulse(s) to the hyperpolarized precursor molecule to create one or both of a non-equilibrium αβ nuclear spin state population and a non-equilibrium pa nuclear spin state population; and
chemically converting the hyperpolarized precursor molecule into the contrast agent molecule by converting the two J-coupled, non-zero-spin, non-equivalent nuclei to two J-coupled, non-zero-spin, equivalent nuclei, wherein the contrast agent molecule comprises a non-equilibrium nuclear singlet spin state population and is chemically convertible to a detection molecule wherein the two J-coupled, non-zero-spin equivalent nuclei are converted to non-equivalent nuclei;
contacting the contrast agent molecule with the target;
allowing the contrast agent molecule to be chemically converted into the detection molecule;
generating a nuclear magnetic resonance signal; and
detecting the nuclear magnetic resonance signal, thereby imaging the target.
24. The method of claim 23 , wherein the target is one of a cell, a tissue, an organ, and a subject.
25. The method of claim 24 , wherein the contacting comprises administering a pharmaceutical formulation comprising the contrast agent to a subject.
26. The method of claim 25 , wherein the subject is a mammal.
27. The method of claim 23 , wherein the two J-coupled, non-zero-spin non-equivalent nuclei of the precursor molecule are selected from the group consisting of 1 H, 13 C, 15 N and 31 P.
28. The method of claim 23 , wherein the hyperpolarizing is performed by dynamic nuclear polarization (DNP).
29. The method of claim 23 , wherein chemically converting the hyperpolarized precursor molecule into the contrast agent molecule comprises dehydrating the hyperpolarized precursor molecule.
30. The method of claim 29 , wherein the dehydrating is accelerated or slowed by changing the pH of an aqueous solvent in which the hyperpolarized precursor molecule is dissolved.
31. The method of claim 23 , wherein one or both of the precursor molecule and the detection molecule is the monohydrate of diacetyl.
32. The method of claim 23 , wherein the contrast agent molecule is selected from the group consisting of diacetyl, oxolin, alendronate, amitryptyline, nortriptyline, succinate, fumarate, maleimide, catechol, naphthalene, naphthoquinone, phenylbutazone, pyridazine, phthalazine, dopamine, L-dihydroxyphenylalanine (L-DOPA) and derivatives thereof.
33. The method of claim 23 , wherein the two J-coupled, non-zero-spin equivalent nuclei of the contrast agent molecule are free of directly bonded hydrogen atoms.
34. The method of claim 23 , wherein the two J-coupled, non-zero-spin, equivalent nuclei of the contrast agent molecule are directly bonded to hydrogen atoms and J-coupled to two other, additional equivalent nuclei, wherein the two other, additional equivalent nuclei are free of directly bonded hydrogen atoms, and whereby application of one or more radiofrequency pulse(s) can transfer a spin state population between the two J-coupled, non-zero-spin, equivalent nuclei and the two other, additional equivalent nuclei.
35. The method of claim 23 , wherein the contrast agent molecule is chemically convertible to the detection molecule under physiological conditions.
36. The method of claim 23 , wherein the contrast agent molecule is converted to the detection molecule via contact with water.
37. The method of claim 23 , wherein the contrast agent molecule is converted to the detection molecule via an enzymatic reaction.
38. The method of claim 23 , wherein the contrast agent molecule is in chemical equilibrium with the hyperpolarized precursor molecule or the detection molecule.
39. The method of claim 38 , wherein the chemical equilibrium is perturbed to interconvert the contrast agent molecule and the hyperpolarized precursor molecule, the contrast agent molecule and the detection molecule, or both.
40. The method of claim 23 , wherein the precursor molecule and the detection molecule have the same molecular structure.
41. The method of claim 23 , wherein providing the contrast agent molecule further comprises incorporating the contrast agent molecule into a pharmaceutically acceptable carrier.
42. The method of claim 23 , wherein providing the contrast agent molecule further comprises encapsulating the contrast agent molecule into a biodegradable delivery format that prevents water contact with the contrast agent molecule prior to complete or partial biodegradation of said delivery format.